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Universidad del Turabo
DETERMINATION OF TOTAL VOLATILE ORGANIC COMPOUNDS (TVOC) IN ELEMENTARY PUBLIC SCHOOLS OF CAGUAS II DISTRICT IN THE MUNICIPALITY
OF CAGUAS, PUERTO RICO
By
Nadya G Cruz-Martínez BS Natural Science-Industrial Chemistry, University of Puerto Rico at Humacao
THESIS
School of Science and Technology Universidad del Turabo
In partial fulfillment of the requirements for the degree of Master of Environmental Science
Environmental Analysis Specialty
(Chemistry Option)
Gurabo, Puerto Rico
December, 2008
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Universidad del Turabo
A thesis submitted in partial fulfillment of the requirements for the degree of Masters in Environmental Sciences
Determination of Total Volatile Organic Compounds (TVOC) in Elementary Public Schools of Caguas II District in the Municipality of Caguas, Puerto Rico
Nadya G Cruz-Martínez
Approved: ________________________ Cesar Lozano, PhD Research Advisor ________________________ Teresa Lipsett-Ruiz, PhD Member ________________________ Pedro Modesto, PE Member
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© Copyright 2008 Nadya G Cruz-Martínez. All Rights Reserved.
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Dedication
I dedicate this work to my grandmother Carmen María Meléndez-Mateo and to
my grandaunt María Emilia Meléndez-Mateo and to those how could not live to see the
outcome of this research work. They will forever be remembered and are always going
to be next to our hearts. It is to them that I dedicate this thesis.
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Acknowledgments
I wish to thank my mother Daisy Martínez-Meléndez and my sister Valesis T.
Cruz-Martínez for their love and belief in me. They bore me, raised me, supported me,
taught me, and loved me. To Raymond Tirado-Agosto for his love, encouragement,
support, patience, and for contributing interest and help on many occasions.
This work would not have been possible without the support and encouragement
of my extended chosen family, on whose constant encouragement and support I have
relied on.
I would like to acknowledge the help of many people during my study; the
Teachers and Directors of the public schools system of Puerto Rico, to the Department
of Education of Puerto Rico, to my colleagues. To the professors: Teresa Lipsett, Pedro
Modesto and César Lozano for supervising my work, I would like to express thanks,
without every one’s determination and perseverance this work would not have been
possible.
It is a pleasure to thank the many people who made this thesis possible. It is
difficult to overstate my gratitude.
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Table of Contents
page
List of Tables…………………………………………………………………………………….vii
List of Figures…………………………………………………………………………………..viii
List of Appendices…………………………………………………………………….…………x
Abstract…………………………………………………………………………………………...xi
Chapter One. Introduction……………………………………………………………………...1
Section 1.01. Study Area Location…………………………………………………….1
Section 1.02. Volatile Organic Compounds…………………………………………..2
Section 1.03. Air Quality in Elementary Schools and Health Effects…..………….4
Section 1.04. Research Objective……………………………………………..………5
Section 1.05. Research Hypothesis……………………….………………………….5
Section 1.06. Research Justification…….……………………………………………6
Chapter Two. Literature Review……………………………………………………………....8
Section 2.01. Environmental Pollution……………………………………………..…8
Section 2.02. Air Pollution……………………………………………………………...9
Section 2.03. Air Pollutants…………………………………………………………...10
Section 2.04. Air Toxics/Hazardous Pollutants……………………………………..12
Section 2.05. Air Quality………………………………………………………………15
Section 2.06. Indoor Air Quality………………………………………………………16
Section 2.07. Indoor Air Pollutant Problems………………………………………..19
Section 2.08. Volatile Organic Compounds: Concept and Terms………………..20
Section 2.09. Total Volatile Organic Compounds………………………………….23
Section 2.10. Microbial Volatile Organic Compounds……………………………..25
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Table of Contents (continued)
page
Section 2.11. Health Effects of VOC’s………………………………………………27
Section 2.12. VOC Detection Methods……………………………………………...29
Chapter Three. Methodology…………………………………………………………………33
Section 3.01. Introduction…………………………………………………………….33
Section 3.02. Research Design………………………………………………………33
Section 3.03. Population Detection……………………………………………..…...34
Section 3.04. Instrumentation…………………….…….…………………………….35
Section 3.05. Data Recollection Procedure…………………………………………37
Section 3.05.1. Data Recollection Procedure Phase One………………………...38
Section 3.05.2. Data Recollection Procedure Phase Two………………………...40
Section 3.06. Data Analysis…………………………………………………………..41
Chapter Four. Results…………………………………………………………………………43
Section 4.01. Phase One of the Research………………………………………….43
Section 4.01. Phase Two of the Research………………………………………….53
Chapter Five. Discussion, Conclusion and Recommendations…………… ……………..60
Section 5.01. Introduction of Discussion…………………….……………………...60
Section 5.02. Discussion of Phase One of the Research….……………………...61
Section 5.03. Discussion of Phase One of the Research….……………………...68
Section 5.04. Conclusion……………………………………………………………..73
Section 5.05. Recommendations…………………………………………………….75
Literature Cited………………………………………………………………………………….77
Appendices……………………………………………………………………………………...90
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List of Tables
page
Table 4.01. Total of first grade students and first grade personnel in each school studied......................................................................44
Table 4.02. Percentage of first grade students and personnel with respiratory conditions...................................................................45
Table 4.03. Temperature data obtained for each school for indoor and outdoor day samples....................................................................46
Table 4.04. Percentage of relative humidity data obtained for each School for indoor and outdoor day samples.................................46
Table 4.05. Wind velocity obtained for each school for indoor and outdoor samples...........................................................................47
Table 4.06. Summarized indoor and outdoor TVOC results measurements for the schools studied.................................................................48
Table 4.07. Comparison of types of indoor ventilation and TVOC results measurements for the schools studied…………………...49
Table 4.08. Total of fist grade students and personnel and the total percentage with respiratory conditions in the school 004……….54
Table 4.09. Temperature data obtained for the school 004 for indoor and outdoor samples...........................................................................55
Table 4.10. Percentage of relative humidity data obtained for the school 004 for indoor and outdoor samples…………..............................56
Table 4.11. Summarized indoor and outdoor TVOC results measurements for the school 004………………………………………………………59
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List of Figures
page
Figure 4.01. Concentration of TVOC versus time for school 002 for indoor and outdoor TVOC data....................................................50
Figure 4.02. Concentration of TVOC versus time for school 003 for indoor and outdoor TVOC data....................................................51
Figure 4.03. Concentration of TVOC versus time for school 004 for indoor and outdoor TVOC data....................................................52
Figure 4.04. Concentration of TVOC versus time for indoor air measurements for school 004......................................................57
Figure 4.05. Concentration of TVOC versus time for outdoor air measurements for school 004......................................................58
Figure 5.01. Indoor TVOC mean concentrations and maximum peak observed at the schools studied...................................................65
Figure 5.02. Outdoor TVOC mean concentration and maximum peak observed in the schools studied...................................................66
Figure 5.03. Comparison chart for indoor and outdoor TVOC maximum peak measurements for each school studied...............................67
Figure 5.04. Comparison chart for indoor and outdoor TVOC averages for each school studied................................................................68
Figure 5.05. Outdoor TVOC mean concentration and maximum peak observed in the school 004 for the days studied..........................70
Figure 5.06. Indoor TVOC mean concentration and maximum peak observed in the school 004 for the days studied..........................71
Figure 5.07. Comparison chart for indoor and outdoor TVOC averages for school 004...............................................................................72
Figure 5.08. Comparison chart for indoor and outdoor TVOC maximum peaks for school 004....................................................................73
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List of Appendices
page
Appendix One. Caguas, Puerto Rico........................................................91
Appendix Two. Secondary production of urban smog oxidants by photochemical reactions in the atmosphere.....................92
Appendix Three. Asthma prevalence in the year 2000................................93
Appendix Four. Volatile organic compound sources..................................94
Appendix Five. Volatile organic compounds emission by source in 2002..............................................................................95
Appendix Six. Hazardous air pollutants of greatest concern..................99
Appendix Seven. Volatile organic compound emission sources.................100
Appendix Eight. List of elementary public schools Caguas II District.......101
Appendix Nine. Instrumentation used......................................................102
Appendix Ten Volatile organic compounds detected by PID 10.6 eV Lamp………………………………………………….……103
Appendix Eleven Volatile organic compounds not detected by PID………108
Appendix Twelve. Aerial photographs of the schools studied......................109
Appendix Thirteen. Meteorological data of Caguas, Puerto Rico..................113
Appendix Fourteen. Wind Resources of Puerto Rico......................................116
Appendix Fifteen. Potential air quality problems in schools.........................117
Appendix Sixteen. Summarized climatologic day data sample....................122
Appendix Seventeen. Summarized TVOC measurement results data..............126
Appendix Eighteen. Glossary terms...............................................................128
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Abstract
Nadya G Cruz-Martínez. (Masters of Science, Environmental Science)
Determination of Total Volatile Organic Compounds (TVOC) in Elementary Public
Schools of Caguas II District in the Municipality of Caguas, Puerto Rico. (December,
2008)
Abstract of a masters thesis at the Universidad del Turabo.
Thesis supervised by Professor César Lozano.
No. of pages in text 132
The goal of this study was to investigate the total volatile organic compounds
(TVOC) concentration upon indoor and outdoor air quality in randomly selected
elementary public schools of the Caguas II District Municipality of Caguas, Puerto Rico,
and to compare it to those from the literature guidelines since there are no TVOC
guidelines from regulating environmental agencies in the United States nor in Puerto
Rico. Baseline measurements of this research compared to TVOC guidelines from the
scientific literature show that TVOC do not seem to be an on-going problem in
elementary public schools of Caguas II District because for most of the time of sampling
measurements, there were no detectable levels of TVOC that could cause any potential
health problems in children or in school personnel (>25mg/m3). Nevertheless, rural
school 004 of this research had continuous TVOC air detection during every outdoor and
indoor air samples having the same pattern of high TVOC peaks early in the morning at
almost three to four times the TVOC guidelines (>25mg/m3) decaying close to midday.
Indoor emission source could come from early cleaning practices in the classroom and
outdoor emission sources could come from nearby industries or transportation
emissions.
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Chapter One
Introduction
Section 1.01. Area of Study Location
This research investigated the presence of total volatile organic compounds
(TVOC) in elementary public schools in the Municipality of Caguas Puerto Rico. Since
Puerto Rico is an Island having limited land supply, many residential and school areas
are located in close proximity to industrial premises and heavily trafficked areas. The air
quality of schools is therefore directly influenced by nearby industrial activities and traffic
conditions which are factors that contribute to air pollution due to heavily traffic
conditions.
Puerto Rico (PR) is an Island located in the Caribbean Basin. It is the most
eastern island of the Greater Antilles in the Caribbean Sea, approximately a thousand
miles southeast of Florida and just east of the Dominican Republic and west of the U.S.
Virgin Islands. The island is approximately 144.81 kilometers wide in an east-west
direction and 48.27 kilometers wide between the north and south coasts.
Puerto Rico is one of the most densely populated islands in the world; it
accommodates 3,808,610 million people in the 8,897 km2 area of the land (US Census
Bureau 2000) having a human population density of 428.08 person/km2. Weather
conditions do not vary greatly across seasons of the year. The average temperature is
27°C, and humidity averages 77 percent (Loyolo-Berrios et al. 2007).
Puerto Rico is divided in 72 municipalities of which only one Municipality served
as the study area. The Municipality of Caguas, Puerto Rico served as the study area for
this research (see Appendix One). Caguas lies in the fertile Caguas valley, it is located
in the Central Mountain Range, to the south of San Juan (Capital of Puerto Rico) at
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approximately 20 km from the international airport; east of Gurabo and San Lorenzo;
and west of Aguas Buenas, Cidra and Cayey.
Caguas is a city with a territory of 115 km2 (Agricultural Extension Service 2005)
divided in 11 bounds. The downtown area of Caguas is denominated Pueblo, and the
other ten (10) bounds are called Barrios which some of them are suburbs (see Appendix
1). On average, the annual amount of rainfall over the territory of Caguas is 155.93
centimeters, and the average annual temperature is 21.60°C (US Census Bureau 2000).
The United States Census Bureau in the year 2000, estimated a total growing population
of 140,502 with a density of 955.1 person/km2.
Section 1.02. Volatile Organic Compounds
Organic pollutants accounts for the vast majority of pollution found in air. Indoor
air in residences, offices, public access buildings and transportation vehicles often
contain volatile organic compounds (VOC) at levels in order of magnitude higher than
those outdoors (Edwards et al. 2001, Jones 1998) from emitting sources such as
cleaning products, vehicle emissions and electronic appliances. Jones (1998) has found
levels of most VOC can be five (5) to ten (10) times higher indoors than outdoors, and
sometimes indoor levels can be more than 100 times higher than outdoor levels
(American Lung Association 2002).
VOC cover a broad spectrum of chemical classes with different physicochemical
and biological properties with inhalation a prominent route exposure due to their volatility
although many VOC can quite readily be absorbed through the skin (Henrich-Ramm et
al. 2000). VOC are an important group of air pollutant to study as they contribute to two
of the most serious air quality problems (Gee et al. 1998). Firstly, they have been
demonstrated to be active in the formation of photochemical smog and ground level
ozone production (Leikauf 2000) (see Appendix 2). Secondly, several VOCs found in
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the air are accepted carcinogens (1,3-butadiene, benzene, formaldehyde and
acetaldehyde) (Gee et al. 1998).
VOC are released into the atmosphere from both biogenic (mainly vegetation)
and anthropogenic sources (e.g. vehicle emissions, the manufacture and use of
petroleum products, biomass burning, landfills and industrial waste water and sewage
treatment plants) where they undergo various chemical degradation processes (Davis
2001, Herbarth et al. 1997). The most important organic chemical pollutants are found
in the gas phase at typical environmental conditions (Levin 2004). There is also concern
about some VOC gases that can go back and forth from liquid to solid state to the gas
state (Levin 2004). Exposure also depends on the intrinsic physical/chemical properties
of each compound, including vapor pressure and solubility in various media (Leikauf
2000).
The ongoing use of over 50,000 commercial chemical substances continue to
present a mayor challenge to environmental health scientists because each compound
could be considered toxic depending on the magnitude of human exposure, the dose
delivered to target organs, and the biological response (Leikauf 2000). Interminent
exposure to VOC’s in high concentrations can depend on regional meteorology,
atmospheric dispersion, transport and removal (Leikauf 2000). This type of exposure is
difficult to monitor or model. Differences in climate, geography, industrial activity, vehicle
age and fuels used will strongly affect the nature of air pollution in different areas (Gee et
al. 1997). The measurement of individual compounds is necessary to assess the
potential health effects of organic chemicals (Levin 2004). Many investigators report the
total of all VOC measured and report it as TVOC or Total VOC concentration (Levin
2004).
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Section 1.03. Air Quality in Elementary Schools and Health Effects
Indoor air quality in schools can have a substantial impact on children’s health,
as an important environment where children may be exposed to pollutants and allergens
(Zhang et al. 2006). School provides a major indoor environment for children away or
apart from their home. Children may spend 10 hours per day at school, and at least 100
hours per year (Zhang et al. 2006) depending on the time that they arrive at the school
and the time they leave the school.
Primary and secondary education is the largest public enterprise in the United
States, employing over three (3) million teachers and school staff who instruct over 47
million children in 92,012 elementary, middle and high schools in 15,000 districts
(Godwin et al. 2006). Surprisingly, given the magnitude of the school population,
information on indoor air quality (IAQ) in schools is very limited (Daisey et al. 2003). The
understanding of exposures and the association of symptoms and health effects of air
quality remain incomplete. IAQ problems may be exacerbated in schools owing to the
potential sensitivity of occupants, the simple and inexpensive building construction in
most schools, minimal landscaping with poor drainage, basic and minimal engineered
ventilation and if any air conditioning system, the lack of preventative maintenance, and
crowded conditions (Godwin et al. 2006). It has been suggested that exposure to air
pollutants and allergens at school was associated with an increase in prevalence of
respiratory symptoms and asthma (Godwin et al. 2006, Daisey et al. 1994). One of the
reasons is that the amount of pollutant delivered to the lung, depends on the person’s
breathing rate (Weisel 2002), in this case it will depend on children’s breathing rate (0.3
L/min). Children differ from adults in their activities, their rate of breathing, their lung
anatomy and physiology, and their organ maturity (Environment Protection and Heritage
Council 2008). The higher risk to children is a result of their higher metabolic rate,
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higher intake of airborne pollutants and lower resilience, resulting in a two to four times
higher absorption rate (Environment Australia 2001).
Investigations examining IAQ problems in PR schools have been complaint-
driven in response to specific concerns or worker compensation issues, or by legislative
initiatives (Puerto Rico Senate 2005, Cámara de Representantes de Puerto Rico 820
2005, Cámara de Representantes de Puerto Rico 892 2005, Cámara de Representantes
de Puerto Rico 2448 2005). Often in schools a specific pollutant, e.g. asbestos or
bioareosols, or combinations of pollutants are addressed (Godwin et al. 2006).
Therefore, reducing exposure to pollutants and allergens at schools and improving
indoor environmental quality is an important public health issue (Zhang et al. 2006).
These outcomes emphasize the importance of knowledge of VOC in elementary
schools.
Section 1.04. Research Objective
The objective of this study was to investigate the total volatile organic
compounds (TVOC) levels upon indoor and outdoor air quality in a representative
sample of elementary public schools of the Caguas II District Municipality of Caguas,
Puerto Rico. Because most of TVOC levels detected in scientific literature research are
attributed to building material construction such as wood and gypsum board, but building
schools in Puerto Rico are made of concrete.
Section 1.05. Research Hypothesis
The total volatile organic compound (TVOC) levels do not exceed concentration
limits found in the scientific literature guidelines in public elementary schools of the
Caguas II District Municipality of Caguas, Puerto Rico if there is no known emission
source present.
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Section 1.06. Research Justification
In Puerto Rico, given the size of the school population, information on air quality
in schools is not known. This is surprising given the fact that children and infants are
among the most vulnerable in terms of air quality, because their organ systems are still
developing, so they are more easily affected by damage to ongoing developmental and
organogenesis processes (Magas et al. 2007). The evidence suggests that
environmental conditions shape attitudes and eventually performance, especially
attendance (Berry 2008).
There are no published data on the detection in air of TVOC or VOC indoors or
outdoors in schools of Puerto Rico. Nevertheless, the Environmental Quality Board of
Puerto Rico has investigated objectable outdoor odors in schools when the issue has
become a controversy or a health hazard in the school. Their findings however are not
publicly available. Much less is known about TVOC levels indoors and outdoors in
schools and if these levels could cause a potential health concern among school
students and personnel.
The majority of indoor air pollution in the United Stated is attributed to come from
poor ventilation from HVAC systems (Heating, Ventilation and Air Conditioning systems)
and from off gassing building materials made such as gypsum boards and furniture. In
Puerto Rico however, buildings and houses are made of cement and ventilation systems
are by open window and/or air conditioning units. Since Puerto Rico is an Island
situated in the Caribbean Sea, it is susceptible to hurricanes and to minimize destruction
the majority of the construction is made of cement. In view of this fact we can expect
that there would be no indoor detectable levels of TVOC in classrooms if there is no
known VOC source and good ventilation is in place. On the other hand TVOC levels
outdoors in public schools will depend greatly on what is around the area of the school if
there is no known VOC source.
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Air quality has become an issue of major concern in countries worldwide but
whether outdoors or indoors, at work or at home, solvents are being inhaled. Despite
the legislative efforts of the Environmental Protection Agency’s “Clean Air Act”, outdoor
air is far from clean. Ambient air levels of VOC are monitored because of their role in
observed increases in levels of tropospheric (ground-level) ozone and decreases in
levels of stratospheric ozone, and because of their importance relating to adverse
human health effects (Davis 2001). Although VOC emissions are a global problem, their
increased use in developing countries has not been accompanied by effective
monitoring programs. Sampling results from national monitoring programs are used by
regulatory agencies to evaluate human and environmental health effects of VOC, to
assess the effects of photochemical oxidation, to provide input on decision making
processes regarding environmental polices and control strategies related to VOC
emissions (Davis 2001).
Consideration of VOC concentration should be made due to the development of
hundreds of new chemicals every year, released in varying quantities into the
environment, and absorbed into the bodies of many American children (Ladrigan et al.
2004). The majority of these chemicals are not adequately evaluated prior to
commercial introduction for their potential toxicity, their potential effects on development,
or their possible interactive effects with other chemicals (Ladrigan et al. 2004).
Furthermore, the minimum exposure levels necessary for a specific toxic effect are
rarely known and the minimum toxic dose estimates for general population grossly over
estimate the doses that could affect sensitive individuals (Reiser et al. 2002).
In this chapter, the idea of this investigative study has been introduced and
related proceedings of the research initiative have been presented. In the next chapter,
the literature review related to this subject is offered.
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Chapter Two
Literature Review
Section 2.01. Environmental Pollution
The demand caused by the increasing population coupled with the desire of most
people for higher material standard of living are resulting in worldwide pollution on a
massive scale (Manahan 2000). The environment is the combination of all external
conditions and influences relating to the life, development and survival of all living things
(British Colombia Clean Air Committee 2005). Environmental pollution can be divided as
water, air and land pollution (Cunningham et al. 2003), but all three areas are linked.
Frequently, time and place determine what may be called a pollutant. It is difficult to give
a simple, comprehensive definition of what is a pollutant. A reasonable definition of a
pollutant is a substance present in greater than natural concentration as a result of
human activity that has a net detrimental effect upon its environment or upon something
of value in that environment (Manahan 2000, British Colombia Clean Air Committee
2005). In some cases pollution is a clear-cut phenomenon, whereas in others it lies
largely in the eyes of the beholder and can be perceived as a contaminant. A
contaminant is not classified as a pollutant unless they have some detrimental effect or
cause deviations from the normal composition of the environment (Manahan 2000).
We come in contact with a wide variety of air pollutants every day. They are
being released in the environment each day. Of special importance to us are certain
emissions that are having a significant effect on the earth’s atmosphere, leading to
changes in the planet’s delicate balance of life (British Colombia Clean Air Committee
2005). A greater than natural amount of greenhouse gases in the atmosphere are
contributing to global climate change. Greenhouse gases are gases that absorb
atmospheric and solar infrared radiation and reflect it back to earth thus increasing
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global warming (Enzler 2008). Many greenhouse gases occur naturally in the
atmosphere, such as carbon dioxide, methane, water vapor, and nitrous oxide, while
others are synthetic (Enzler 2008, British Colombia Clean Air Committee 2005). Those
greenhouse gases that are man-made include chlorofluorocarbons (CFCs),
hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs), as well as sulfur hexafluoride
(SF6) (Enzler 2008, WG Environment 2004). Past and future anthropogenic emissions
of greenhouse gases (carbon dioxide, methane and nitrous oxide) enhance global
warming (Enzler 2008). This phenomenon is the progressive rise of the earth’s surface
temperature thought to be caused by the enhanced greenhouse effect. Global warming
may be responsible for changes in global climate patterns (British Colombia Clean Air
Committee 2005). Industrialized nations have committed to reduce their contribution of
greenhouse gases to the atmosphere through the Kyoto Protocol (WG Environment
2004). The Kyoto Protocol is a pact agreed on by governments at a United Nations
conference in Kyoto, Japan 1997 to reduce the amount of greenhouse gases emitted by
developed countries by 5.2 percent of 1990 levels during the five-year period 2008-2012.
Section 2.02. Air Pollution
Air pollution is a major problem that has been recognized throughout the world
for hundreds of years. Air pollution is the term used to describe any harmful gases
and/or particles in the air we breathe (Manahan 2000). Pollutants have a distinct
chemical or physical structure or a distinct effect on human health and can form in
various ways (Manahan 2000).
Air pollution is caused by both human and natural sources (Cunningham et al.
2003). Human sources include traffic, agriculture and/or industry. Natural sources
include dust storms, volcanic eruptions and/or emissions from plants. Emissions may be
roughly described as the pollutants that are dumped into the air. According to Godish
(2001) is important to know at least, which pollutants are emitted, how much of each,
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from what kind of source and the source location (see Appendix 4). Air pollution can be
divided in categories according to the source it is derived from. Air pollution sources
may be biological (pollen, small insects and microorganisms [bacteria, fungi, yeasts and
algae]), physical (sound, smell, thermal pollution and radioactive radiation) or chemical
(such as ozone, aerosols and ammonia) (Enzler 2008).
These types of pollution undergo a number of processes. These processes are
(Enzler 2008): emission (contaminants are released into the air), transport (contaminants
are transported to different locations through air), exchange (compounds react with other
compounds in air), distribution (contaminants are distributed in air), immission
(contaminants remain in a certain area), deposition (contaminants are deposited in a
certain area, on the soil or on objects). In the atmosphere these chemicals can react
with other chemicals to form more dangerous substances. The weather plays an
important role in the formation, transformation and/or disappearance of air pollution
(Enzler 2008). This is mainly influenced by wind and temperature. Rain can remove
pollutants from air, causing soil and water pollution (Cunningham et al. 2003). Sunlight
can also aid in the conversion of air pollutants to different substances.
Section 2.03. Air Pollutants
Air pollutants are divided in two classes: primary and secondary pollutants, by
the United States Environmental Protection Agency (EPA). Primary pollutants are those
released directly from the source into the air in a harmful form (Cunningham et al. 2003).
Secondary pollutants are modified into a hazardous form after they enter the air or are
formed by chemical reactions as components of the air mixture and interaction
(Cunningham et al. 2003).
The most common pollutants that affect the air are sulphur dioxide, nitrogen
oxides, volatile organic compounds, carbon monoxide, dust particles, ozone and,
radioactive radiation (Cunningham et al. 2003, Enzler 2008, Manahan 2000).
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Sulphur dioxide (SO2) is mainly emitted during the combustion of sulphur-
containing fossil fuels, such as crude oil and coal. Sulphur dioxide concentrations in air
have decreased in the past two decades, mainly because we use more non-sulphur-
containing fuels for the generation of energy. Sulphur dioxide is a stinging gas and as a
result it can cause breathing problems in humans. In moist environments, sulphur
dioxide may be converted to sulphuric acid. This acid causes acidification and winter
smog.
Nitrogen oxides (NOx) are emitted by traffic and combustion installations, such as
power plants, and industries. Nitrogen oxides are gasses that react with other air
pollutants when they are present in air. For example, nitrogen oxides play an important
role in the formation of ozone in the lower atmosphere, and in acidification and
eutrophication processes. They can deeply penetrate the lungs and damage human
lung functions.
Volatile Organic Compounds (VOC) can be an array of different contaminants,
such as carbohydrates, organic compounds and solvents. These organic compounds
usually derive from petroleum and gasoline reservoirs, industrial processes and fuel
combustion, paint and cleanser use, or agricultural activities. VOC play an important
role in ozone formation in the lower atmospheric layer, the main cause of smog. VOC
can cause various health effects, depending on the kind of compounds that are present
and their concentrations. Effects can vary from smell nuisance to decreases in lung
capacity, and even cancer.
Carbon monoxide (CO) is a gas that exists during the incomplete combustion of
fuels. When we let a car engine run in a closed room, carbon monoxide concentrations
in the air will rise extensively. Carbon monoxide contributes to the greenhouse effect,
smog and acidification. The gas can bind to hemoglobin in blood, preventing oxygen
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transport through the body. This results in oxygen depletion of the heart, brains and
blood vessels, eventually causing death.
Dust particles form a complex of organic compounds and minerals. These can
derive from natural sources, such as volcanoes, or human activities, such as industrial
combustion processes or traffic. Particles are categorized according to their size. The
smallest particles have the ability to transport toxic compounds into the respiratory tract.
Some of these compounds are carcinogenic. The upper respiratory tract stops the
larger dust particles. When they are released into the environment, dust particles can
cause acidification and winter smog.
Ozone (O3) is created through photochemical transfer of oxygen. This process
takes place under the influence of ultra violet sunlight (UV), aided by pollutants in the
outside air. Ozone causes smog and contributes to acidification and climate change.
Ozone is an aggressive gas, which can easily penetrate the respiratory tract. When
humans are exposed to ozone, the consequences may be irritation of the eyes and of
the respiratory tract.
Radioactive radiation and radioactive particles are naturally present in the
environment. During power plant incidents or treatments of nuclear waste from a war
where nuclear weapons have been used, radioactive radiation can enter the air on
account of humans. When humans are exposed to high levels of radioactive radiation,
the chances of serious health effects are very high. Radioactive radiation can cause
genetic alteration in the deoxyribonucleic acid (DNA) structure and can cause cancer.
Section 2.04. Air Toxics/ Hazardous Pollutants
Toxic air pollutants are those pollutants that cause or may cause cancer,
reproductive effects or birth defects (American Lung Association 2002). Examples of
toxic air pollutants include benzene, which is found in gasoline; perchloroethylene, which
is emitted from some dry cleaning facilities; and methylene chloride, which is used as a
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solvent and paint stripper by a number of industries. Other listed air toxics include
dioxin, asbestos, toluene, cadmium, mercury, chromium and lead compounds (American
Lung Association 2002) (see Appendices 5 and 6). People exposed to toxic air
pollutants at sufficient concentrations may experience damage to the immune system,
neurological, reproductive, developmental and respiratory and other health problems
(American Lung Association 2002).
According with EPA regulations listed under section 112 of the Clean Air Act
(CAA), VOC are known air toxics. Air toxics are known as hazardous air pollutants
(HAPs), which are pollutants that may cause serious health effects or adverse
environmental and ecological effects. With the passage of the 1990 Clan Air Act, the
United Sates EPA has been charged with the task of regulating the source of emission.
The Clean Air Act identifies 188 HAPs, some common ones are perchloroethylene (from
dry cleaners), mercury (from coal combustion), methylene chloride (from consumer
products such as paint strippers), and benzene and 1,3-butadiene (from gasoline) (EPA
2003).
HAPs are emitted to the ambient air from thousands of sources, including large
and small stationary sources, area sources and mobile sources. A stationary source is
any building, structure, facility, or installation subject to regulation which emits or may
emit any air pollution. These sources include power generating plants, landfills,
petroleum facilities, chemical plants, mining operations, cement and glass manufacturing
companies, and many other heavy industrial sources. Pollutants are emitted into the air
from these plants through fossil fuel combustion, chemical processes, and the grinding
or pulverizing of metals for cement, fertilizers, etc. These processes emit a number of
harmful contaminants into the air including sulfur dioxide, nitrogen oxides, carbon
dioxide, synthetic compounds, and particulate matter. Area sources do not individually
produce sufficient emissions to qualify or to be reported as an individual point source,
14
but collectively the emissions from all the small sources of the same type in an area may
be significant and are reported as a category. Mobile sources is a term used to describe
a wide variety of vehicles, engines, and equipment that generate air pollution and that
move, or can be moved, from place to place. On a broad scale, in 1993, 3.7 million tons
of HAPs were emitted, with approximately 41% from mobile sources, 35% from area
sources and 24% from point sources (Weisel 2002). Based on the National Toxic
Inventory database, nationwide air toxics emissions have dropped approximately 23%
between 1990 and 1996 (American Lung Association 2002).
Individual HAPs are present in the environment at significantly lower
concentrations than the criteria pollutants and are often present at higher concentrations
in indoor air than outdoor air (Weisel 2002). The presence of criteria pollutants along
with HAPs in ambient air makes it difficult to distinguish the effects of HAPs from those
of the criteria pollutants or to determine if there is an interactive effect (Weisel 2002).
HAPs can produce nonspecific respiratory responses (Weisel 2002). Thus, the
combined concentrations may need to be considered when evaluating respiratory
exacerbation and not just exposure to individual compounds. It has been known for
more than a decade that exposure to the mixture of VOC present in indoor air which
includes many HAPs such as aromatic and chlorinated organic compounds, can irritate
the mucus membrane in the respiratory tract in both healthy and sensitive individuals
(Weisel 2002, Wang et al. 2006).
EPA does not set health standards for these pollutants; instead, the Clean Air Act
mandates a two phase approach (EPA 2003). In the first phase, EPA establishes
standards for source categories (major sources, and mobile sources). In the second
phase, EPA assesses how well the standards are reducing health and environmental
risks and based on these assessments determines what further actions are necessary to
address any significant remaining, or residual, health or environmental risks.
15
Also, section 313 of the Superfund Amendments and Reauthorization Act
(SARA) has set a requirement for the reporting of toxic chemical releases resulting in an
extensive database of toxic chemical release inventory for VOC’s and other chemicals.
Section 111 of the CAA required EPA to identify categories of new and modified sources
that contribute significantly to air pollution and endanger public health or welfare. After
identifying approximately 60 source categories (e.g., grain elevators, fossil fuel-fired
generators, steam generating units) that are designated by size as well as type of
process, EPA established uniform, national emission standards known as NSPS (New
Source Performance Standard) in 40 CFR 60 (EPA 2003).
There are other federal laws that regulate VOC emissions directly or indirectly
through the Occupational Health and Safety Administration (OSHA) Standards and other
local and state regulations. OSHA has no exposure limits for groups of chemicals that
researchers believe might act synergistically. As a result, the standards do not usually
protect people from the complex mixture of chemicals that might be found in indoor air
since health effects are being seen at levels much lower than the OSHA standards.
Section 2.05. Air Quality
Air quality has become an issue of major concern in countries worldwide and
many are attempting to develop strategies and interventions aimed at improving air
quality (Gee et al. 1998). Air quality is a direct measure of the concentration of the air
we breathe (Godish 2001). Ambient air quality is the condition of the air, it depends not
only on emissions but also on what happens to them after they are released, this is, on
how much they are dispersed by the wind and how they react in the atmosphere (Godish
2001).
Outdoor air pollution is a dynamic system in which the physical and chemical
processes affecting the accumulation of pollutants in the atmosphere are constantly
changing, largely driven by complex meteorology and photochemistry (Mitchell et al.
16
2007). In contrast, indoor air pollution considers only pollution sources strength and
dilution by air exchange (Mitchell et al. 2007). Trivial actions such as walking across
carpets or improperly using cleaning materials can cause airborne hazardous
substances (Brickus et al. 1998). Similarly, operations of laser printers, photo
duplication machines, vacuum cleaners or even toilet flushing are known sources of
indoor air pollution (Brickus et al. 1998). Thus, inadequate ventilation may also result in
accumulation of pollutants.
Poor air quality produces discomfort, decreases concentration and increases
absenteeism (Brickus et al. 1998). Conversely, improved air quality can lead to
improved productivity. Knowledge of the pollutants concentrations both indoor and
outdoors is therefore critical for an evaluation of their potential health effects.
Section 2.06. Indoor Air Quality
Life today is hectic and between jobs, studies, grocery shopping, hopping in and
out of the car and being at home, we spend a total estimate of 90 percent of our time
indoors (Brown 2004, Wu et al. 2007, Housing Leaflet 250 2004, Darlington et al. 2000,
Höppe et al. 1998, Jones 1998, American Lung Association 2002). For infants, the
elderly, persons with chronic diseases and most urban residents, the proportion is
probably higher (American Lung Association 2002). As we spend more time in enclosed
spaces, indoor climate becomes the dominant climate to which we are exposed (Höppe
et al. 1998). Indoor air quality (IAQ) as the name implies, simply refers to the quality of
the air in an enclosed environment: office, house, buildings, school, etc. (NIOSH 1997).
As stated before, if indoor air is in poor quality, it produces discomfort, decreases
concentration and increases absenteeism (Brickus et al. 1998) either in jobs or at
school.
The quality of indoor air in the indoor environment can be altered by a number of
factors: release of VOC from furnishings, floor and wall coverings, and other finishing
17
materials or machinery; inadequate ventilation; poor temperature and humidity control;
re-entrainment of outdoor VOC; and the contamination of indoor environment by
microbes (particularly fungi) (Bayer et al. 2007). Poor indoor air quality may lead to what
is known as the “sick building syndrome” (SBS). The SBS is when at least 20 percent of
the people occupying a building experience symptom of illness for a period of two weeks
or longer, but the source of the symptoms cannot be determined (Bas 2003). This term
is used to describe situations in which building occupants experience acute health and
comfort effects that appear to be linked to time spent in a building. WHO has estimated
that as many as one third of the world’s buildings today can be considered sick (Bas
2003). Building occupants complain of symptoms associated with acute discomfort, e.g.,
headache; eye, nose, or throat irritation; dry cough; dry or itchy skin; dizziness and
nausea; difficulty in concentrating; fatigue; and sensitivity to odors. Most of the
complainants report relief soon after leaving the building.
Since 1985 scientists have known that indoor air is awful compared to outdoor air
if an adequate ventilation system is not in place (Crinnion 2000). In closed spaces the
operational cost of quantity of ventilation has been given higher priority than quality of
ventilation. The result has been more recycling of air, rather than a greater exchange of
indoor air with outdoor air.
Contaminants reach occupant breathing-zones by traveling from the source to
the occupant by various pathways (Levin 2004). Normally, the contaminant travels with
the flow of air. Air moves from areas of high pressure to areas of low pressure (Levin
2004). That is why controlling building air pressure is an integral part of controlling
pollution and enhancing building IAQ performance (Levin 2004). Pressure differences
will control the direction of air motion and the extent of occupant exposure (Levin 2004).
The locations of highest concern are those involving prolonged continuous exposure; i.e.
home, school and workplace (American Lung Association 2002).
18
Contaminants can come from a variety of sources and by an assortment of
pathways. The majority of indoor air pollutants can come from the building itself, its
contents, or its occupants and their activities (Levin 2004, Liccardi et al. 2001) (see
Appendix 7). Pollutants found in indoor air are often several times higher than outdoors,
and since people spend the majority of time indoors (Levin 2004, Reiser et al. 2002,
Cheng-Lee et al. 2002, Ten-Brinke et al. 1998, Rehwagen et al. 1998); it is important to
recognize and control indoor air pollution.
During the last decade, there has been a significant increase in public concern
about IAQ (NIOSH 1997). The indoor environment has been recognized as a major
source of exposure to allergens and toxic chemicals (Jones 1998). While indoor air
quality is an important concern to the United States Environmental Protection Agency
(EPA), the ramifications of indoor air pollutants in the workplace has made indoor air a
concern of the National Institute for Occupational Safety and Health (NIOSH), the
Occupational Safety and Health Administration (OSHA), the Consumer Product Safety
Commission, (CPSC), the Department of Energy (DOE), the General Services
Administration (GSA), the Department of Transportation (DOT) and the Centers for
Disease Control (CDC). State and local governments often follow the lead of these
agencies with indoor air quality legislation and ordinances (CCIM Institute 2006). Some
known and postulated adverse health effects associated with poor indoor air quality are
allergies, asthma, infections, hypersensitivity pneumonitis, inhalation fevers, mucosal
irritation central nervous system effects (including depression), dermatitis and even
some forms of cancer (Wu et al. 2007).
As indicated above, exposure to allergens and toxins is thought to exacerbate
respiratory conditions, in particular, asthma (Magas et al. 2007, McConnell et al. 2006,
Selgrade et al. 2006, Richardson et al. 2005, Kheradmand et al. 2002, Nicolai 2002,
Liccardi et al. 2001, Kimber 1998, Jones 1998). Asthma is a respiratory disease
19
involving inflammation of the airways and reversible symptoms of bronchospasm
(Richardson et al. 2005). National data shows increases in prevalence of asthma in all
ages, race and ethnic groups and among both adults and children (Magas et al. 2007,
Redd 2002). As the number of cases of asthma was increasing so was the number of
persons dying from asthma (Redd 2002). Children and infants are among the most
vulnerable because their organ systems are still developing, so they are more easily
affected by damage to developmental and organogenesis processes (Magas et al.
2007). Several studies have determined that the estimated direct and indirect costs of
this disease are to be $6.2 billion (Salgrade et al. 2006, Redd 2002, Weisel 2002).
People with pre-existing respiratory conditions are more susceptible to the
adverse effects of air pollution (Magas et al. 2007). In other words, environmental
pollutants may affect allergic sensitization (Kimber 1998). This makes sense do to the
given amount of time that most individuals spend indoors. It seems that the indoor
environment may have an important role to play in allergic disorders (Jones 1998).
Section 2.07. Indoor Air Pollutant Problems
Advances in construction, technology and other transformations have
undoubtedly led to more comfortable living conditions resulting in warmer, more humid
houses with poorer availability to fresh air (Jones 1998). During the 1970’s, ventilation
requirements were changed to conserve fossil fuels and virtually air-tight buildings
emerged (NIOSH 1997). New building methods emphasized a reduction in incidental
exchange of inside and outside air so the internal climate would not diffuse, and
therefore less energy would be needed to maintain temperature (Crinnion 2000). These
conditions provide an environment in which airborne contaminants are readily produced
and build up to much higher concentrations than typically encountered outside (Jones
1998). Inadequate ventilation can increase indoor pollutant levels by not bringing in
enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air
20
pollutants out, allowing concentrations to built up (American Lung Association 2002).
High temperature and humidity levels can also increase concentrations of some
pollutants (American Lung Association 2002). Concern over indoor air has now risen to
such extent that the United Stated Center of Disease Control (CDC) has classified
indoor air pollution as a factor of high environmental risk (Jones 1998; CDC 1994).
There are various common sources of indoor air pollutants (AERIAS 2007). The
National Institute for Occupational Safety and Health (OSHA) investigators have found
IAQ problems caused by ventilation system deficiencies, overcrowding off-gassing from
materials in the office and mechanical equipment, tobacco smoke, microbiological
contamination and outside air pollutants (NIOSH 1997). Some of these pollutant
sources are moisture (can come from showers, clothes washing, cooking, dishwashers,
humidifiers and/or flood damage), gases from building material (paint, carpet,
furnishings, paneling, textiles, insulation, fiber glass), office machines
(copying/duplicating machines, computers, laser printers), cigarette, pipe and cigar
smoke (Ministry of National Health and Welfare 1995). Other sources can be common
chemicals, such as, pesticides, automotive products, cleaning products, personal care
products. Some everyday uses of gas/wood burning appliances (gas stoves, dryers,
and space heaters), fireplaces or everyday activities can become sources of air pollution
(Wolkoff 2003, Edwards et al. 2001, British Colombia Clean Air Committee 2005).
Section 2.08. Volatile Organic Compounds Concept and Terms
To understand what volatile organic compounds are, we must first understand
each term. The term “Organic Compounds” covers all chemical containing carbon and
hydrogen (Ministry of National Health and Welfare 1995). "Volatile" is a term meaning
that these chemicals evaporate, or get into the air easily at room temperature (Manahan
2000). The high volatile property is why these compounds are an air quality concern.
"Organic" is another chemical term meaning that these types of chemicals contain
21
carbon (Manahan 2000). Since carbon burns, many of these chemicals, including
organic solvents, are flammable (Wang et al. 1996, AERIAS 2007).
VOC are those organic compounds that have boiling points roughly in the range
of 50-250°C (Ministry of National Health and Welfare 1995, Herbarth et al. 1997). There
are probably several thousand chemicals, synthetic and natural, that can be called VOC
(Ministry of National Health and Welfare 1995). There is no universally accepted
consensus as to what constitutes a VOC (Davis 2001).
VOC are chemicals that evaporate easily at room temperature (Minnesota
Department of Health 2005). Many products emit “off-gas” VOCs. Some examples of
VOC emissions sources are: paints, varnishes, moth balls, solvents, gasoline,
newspaper, cooking, cleaning chemicals, vinyl floors, carpets, photocopying, upholstery
fabrics, adhesives, sealing caulks, cosmetics, air fresheners, fuel oil, vehicle exhaust,
pressed wood furniture, environmental tobacco smoke (second hand smoke) (Minnesota
Department of Health 2005).
Numerous investigations concerning the quality of indoor air have been carried
out, resulting so far in the identification of more than three hundred VOC in non-industrial
indoor air (Hong et al. 2001). No standards have been set for VOCs in non-industrial
settings. However, VOC’s can be released from products while in use and to some
degree while they are in storage. Example, substances associated with combustion,
liquid-process printers or copiers (Edwards et al. 2001, Cheng-Lee et al. 2002).
However, the amounts given off tend to decrease as the product ages and dries out
(British Colombia Clean Air Committee 2005). In addition, these compounds differ
substantially in their effective atmosphere half-lives (Herbarth et al. 1997). They also
play an important role as essential constituents of the photochemical oxidation
processes, and thus are precursors of smog (Herbarth et al. 1997, Davis 2001).
22
The health effects of VOC can vary greatly according to the compound, which
can range from being highly toxic to having no known health effects. The health effects
of VOC will depend on the nature of the VOC, the level of exposure, and length of
exposure (DEC 2008). VOC include a variety of chemicals that can cause eye, nose,
and throat irritation, headache, nausea, dizziness and skin problems (British Colombia
Clean Air Committee 2005). Higher concentrations may cause irritation of the lungs, as
well as damage to the liver, kidney and/or the central nervous system (British Colombia
Clean Air Committee 2005). VOCs primarily act in the body as both peripheral and
central nervous system neurotoxins (Crinnion 2000). When the central nervous system
is primarily affected the symptoms can include diminished cognition, memory, reaction
time, and hand-eye and foot-eye coordination, and balance and gait disturbances
(Crinnion 2000). Peripheral neurotoxicity usually results in paresthesias, tremors and
diminished fine and gross motor movements. VOCs have been associated with
immunological problems, including increased cancer rates and inmunotoxicity (Reiser
2002, Crinnion 2000). Some VOC are suspected to cause cancer in humans and have
been known to cause cancer in animals (Brickus et al. 1998). The health effects of VOC
depend on the level and length of exposure.
The US Environmental Protection Agency Total Exposure Assessment
Methodology (TEAM) studies have found indoor VOC levels that were two (2) to five (5)
times higher than outdoors (Minnesota Department of Health 2005). VOC have many
sources in the environment. Data on airborne VOC in urban and rural areas in the US
have been reviewed and VOC are found in the air of most urban areas (Sweet et al.
1992). Major anthropogenic sources of VOC in urban areas include the use of solvents,
and gas leakage from natural gas and liquefied petroleum gas (Na et al. 2001).
Unfortunately, they are difficult and expensive to measure. Their importance is related
to the remarkable increase in new materials and new processes (Grimsrud 2004).
23
Section 2.09. Total Volatile Organic Compounds
Identification of individual VOC are expensive and time consuming, and
invariably the total is underestimated because the VOC present at very low
concentrations are difficult to identify or measure (Ministry of National Health and
Welfare 1995). The difficulty in understanding the large numbers of VOC led
researchers to the concept of TVOC (Grimsrud 2004). Measurements of TVOC record
TVOC present without distinguishing different chemicals (Ministry of National Health and
Welfare 1995). In fact, a sample may be dominated by one, innocuous organic chemical
and have a very high value or may have one very toxic chemical along with few others at
low concentration resulting in a very low TVOC concentration (Levin 2004).
Regarding health, evaluating the effects of single compounds may not always be
adequate. The transport of chemicals via migration in environmental media occurs
frequently, sometimes with adverse environmental and human health consequences
(Moseley et al. 1992). Only two percent (2%) of at least 60,000 chemicals that are
widely used have been comprehensively studied for toxic effects and of these, they have
rarely been studied in combined exposure, which actually exists in the real world (Reiser
et al. 2002). Most studies to date have been conducted on single chemicals but less in
known about health effects of combined chemical exposure.
VOC measurement concept does not include the possibility for interactions
between the many compounds in indoor air and no toxicological arguments for exclusion
of some and inclusion of other toxicologically relevant organic vapors and gasses
(Mølhave 2003). In addition it must be remembered that different VOCs have different
toxicity and there is no true standardization procedure for TVOC measures (Mølhave
2003). The TVOC level in a building or home is a good indicator of whether or not there
are elevated levels of VOC. There are often dozens, and sometimes hundreds, of
individual compounds present at concentrations of 1µg/m3 or more (Michaels
24
Engineering 2004). The TVOC indicator can be used in relation to exposure
characterization and sources identification but for VOC only (Mølhave 2003).
One of the reasons TVOC is used is due to interpretation. One single parameter
is simpler and faster than the interpretation of the concentrations of several dozens of
VOC typically detected indoors (European Collaborative Action 1997). In addition,
editors of scientific journals tend to avoid printing long lists of compounds (European
Collaborative Action 1997).
Objections to the TVOC concept began to develop when people noted that many
organic compounds are strong irritants at very small concentrations while others are
quite benign at much larger concentrations. Two significant papers in 1997, Andersson
et al. (1997) and Mølhave et al. (1997), have caused the concept to change from
important guidance about VOC in a space to become, at most, a recommended
procedure for pre-screening a space to indicate a potential problem (Grimsrud 2004).
This concept has led to general guidance about TVOC that can be found in
several sources (Grimsrud 2004). Data in the published technical literature provide the
following guidance in the interpretation of VOC air sampling results. This guidance
includes the following:
a) TVOC concentrations in non-compliant buildings are typically in the range of 200-
500µg/m3 (AQS 1995).
b) Recently renovated spaces may have TVOC levels of up to 30,000µg/m3
(30mg/m3). With adequate ventilation, these levels can decrease to below
1000µg/m3 within a 30-day period (AQS 1995).
c) Based on an extensive literature review, analysis of health related data and a
survey of unpublished measurements, means concentration of individual VOC in
established buildings were generally found to be less than 50µg/m3, with most
below 5µg/m3 (Brown 1994).
25
d) Mean TVOC concentrations in established public buildings were found to be in
the range of 70-410µg/m3 (Brown 1997).
In the literature we can find that TVOC concentration typically range from 50-
1000 µg/m3 over long periods of time and can reach hundreds of mg/m3 for periods of
minutes and hours (European Collaborative Action 1997, Daisey et al. 2003). The low,
long-term concentrations result from the presence of a wide variety of synthetic and
natural products, and from people and their activities (Reiser et al. 2002). The high,
short-term concentrations are most commonly reached during building construction or
renovation, and when certain personal care products, hobby materials or cleaning
agents are used (Reiser et al. 2002). The Indoor Air Goal concentrations recommended
in 1992 by the National Health and Medical Research Council (Australia) were 500
µg/m3
for total VOCs and 250 µg/m3
for any single VOC, both defined by a one-hour
averaging period (Brown 1997).
Researchers have shown that there are signs of irritation and discomfort when
the concentration of TVOC exceeds 3 mg/m3 (Grimsrud 2004, AERIAS 2007) and no
effects when TVOC level is less than 0.2 mg/m3 (Bush et al. 2006, AERIAS 2007).
Significant discomfort and headaches are likely if concentrations fall in the range of 3
mg/m3 – 25 mg/m3; while above 25 mg/m3 exposures may cause significant neurotoxic
effects (Grimsrud 2004, AERIAS 2007). However, this measurement cannot be used as
an indicator of potential heath effects since the content and proportions of the mixture of
VOC can vary greatly from one sample to another (Levin 2004).
Section 2.10. Microbial Volatile Organic Compounds
Nevertheless, not just man-made materials produce VOCs. Some molds and
fungi can give off VOC gases known as microbial VOCs (MVOC) (Schleibinger et al.
2005, AERIAS 2007). These MVOCs are responsible for the characteristic odors
26
produced by molds characterized as "musty, earthy, and moldy" (Ministry of National
Health and Wealfare 1995, Abott 2002). Microbial VOCs are unique and include certain
aldehydes, alcohols, and ketones that are not typically found to emit from building
materials (Schleibinger et al. 2005, AERIAS 2007). Other MVOC are esters, carboxylic
acids, lactones, terpenes, sulfur and nitrogen compounds, and aliphatic and aromatic
hydrocarbons (Bush et al. 2006).
Toxic mold is a term that generally refers only to those molds capable of
producing mycotoxins (Davis 2001). Mycotoxins are natural organic compounds that are
capable of initiating a toxic response to vertebrates (Davis 2001). Over 100 species of
molds found indoors are capable of producing mycotoxins (Vasselli 2005). Mycotoxins
are low-molecular-weight chemicals produced by molds that are secondary metabolites
unnecessary for the primary growth and reproduction of the organisms (Bush et al.
2006). Mycotoxins are not cumulative toxins, having half-lives ranging from hours to
days depending on the specific mycotoxins (Bush et al. 2006). Molds know to potentially
produce mycotoxins and which have been isolated in infestations causing adverse
effects include certain species of Acremonium, Alternaria, Aspergillus, Chaetomium,
Cladosporium, Fusarium, Paecilomyces, Penicillium, Stachybotrys, and Trichoderma
(Bush et al. 2006). This list is not all –inclusive.
The conditions under which dangerous mycotoxins will be produced are not well
understood (Vasselli 2005). Most molds found in indoor air are saprotrophic, meaning
they gather their food from dead moist organic matter such as wood, paper, paint, fabric,
plant soil, dust and cooked or raw foods (Davis 2001). Molds have been found growing
in private homes, office buildings, schools, automobiles, and other locations where
organic matter and water are left unattended (Davis 2001). Floods, leaking pipes,
leaking windows, leaking roofs are all potential sources of moisture that can lead to mold
infestation (Davis 2001). Increased ambient humidity as a result of inadequate
27
ventilation or improper drying of flooded areas can also lead to mold growth (Davis
2001). The key to limiting mold exposure is to prevent the germination and growth of
mold (Davis 2001). Molds grow by gaining nutrients they need through the
decomposition of organic matter (Davis 2001). The introduction of mycotoxins into the
living space can be driven by “sporadic” events associated with: changes in environment
associated with elimination/reduction in moisture source; unplanned air path creation
due to indoor/outdoor pressure variations, mechanical disturbances, etc (Vasselli 2005).
By the inhalation path, mycotoxins have been shown to be 10 to 40 times more toxic
then by ingestion in both animals and humans (Vasselli 2005).
Molds are necessary to plant, animal and human life (Davis 2001). Molds are the
most typical form of fungus found on earth comprising approximately 25% of the earth
biomas (Davis 2001). There are also essential components of our planet’s ecosystem
providing decomposition of many organic substances (Davis 2001). However, it is also
the case that excessive exposure to molds has been a health issue for humans for
many, many years. Molds have been implicated as in a variety of health effects in
humans ranging from minor allergic reactions and exacerbation of asthma, to brain
damage.
Molds cause adverse human health effects through three (3) specific
mechanisms: generation of a harmful immune response (e.g., allergy or hypersensitivity
pneumonitis [HP]), direct infection by the organism and toxic-irritant effects from mold
byproducts (Bush et al. 2006). The Occupational Health and Safety Administration
defines an irritant as a material causing ‘‘a reversible inflammatory effect on living tissue
by chemical action at the site of contact” (Bush et al. 2006).
Section 2.11. Health Effects Of VOC’s
Human exposure to air toxics occurs when individuals breathe air containing
these constituents (Weisel 2002). The concentrations of air toxics vary with time and
28
location, and as people move from locations and activities, the resultant exposure
changes (Weisel 2002). Identification of sources of potentially harmful compounds in
different microenvironments provides the only mechanism of reducing levels of these
compounds in each microenvironment and ultimately leading to cost effective reduction
in population exposures (Edwards et al. 2001). More importantly it allows us to prioritize
those sources that contribute most significantly to exposures and target subpopulations
with elevated exposure levels.
It is generally assumed that indoor air pollution, one way or another, causes an
increase of indoor complaints, e.g. eye and airway irritation and odor annoyance
(Schleibinger et al. 2005, Reiser et al. 2002, British Colombia Clean Air Committee
2005). Air pollution can decrease lung function, increase emergency room visits for
asthma, increase hospitalizations for respiratory diseases, and increase mortality (Chen
et al. 2000). People with respiratory conditions are clearly are at an increased risk from
the adverse effects of air pollution (Leikauf 2000) and children’s health can also be
affected by air pollution (Chen et al. 2000). Poor indoor air quality can be a significant
health, environment and economic problem, and has become a public health issue and
liability from employers and building managers who fail to provide a ‘safe’ work
environment (Brown 2004). Indoor air levels of VOC are closely associated with
increased rates of asthma (Kheradmand et al. 2002, Pachter et al. 2002, Kimber 1998)
and chronic bronchitis, especially in children (Leikauf 2000).
Estimates of the average rates of asthma prevalence increased over time across
all age groups, and asthma mortality also increased (Ladrigan et al. 2004). Various
asthma studies arranged in the United States of America indicate that among Hispanic
cultures, Puerto Rican heritage had the highest rates of asthma and had the highest
asthma mortality rates among Hispanics (Perez-Perdomo et al. 2003, Homa et al. 2000,
29
Findley et al. 2003, Lara et al. 1999, Pachter et al. 2002, Smith et al. 2005, Rose et al.
2006, Ledogar et al. 2000).
The Behavioral Risk Factor Surveillance System (BRFSS) of Puerto Rico which
is an ongoing, state-based surveillance system that collects monthly information about
modifiable risk factors for chronic diseases and other leading causes of death, stated in
2002 that Puerto Rico had a substantially higher than the median asthma prevalence
compared with the United States and its territories (Perez-Perdomo et al. 2003) (see
Appendix 3). Indeed, PR also had the highest asthma prevalence reported during the
year 2000 (Perez-Perdomo et al. 2003). Nearly half of the asthmatic people reported
having children with asthma, and less than one third of non-asthmatics reported having
children with asthma (Perez-Perdomo et al. 2003). From 1980 to1996, the number of
Americans with asthma had doubled to almost 15 million, with children younger than five
(5) years of age, experiencing the highest rate of increase (Perez-Perdomo et al. 2003).
More than ten (10) million school days are lost because of asthma each year (Perez-
Perdomo et al. 2003) accounting for the leading cost of school absenteeism each year
(Air Quality Sciences 2007). Moreover, the disease kills more than 5,000 Americans
and results in half a million hospitalizations every year (Perez-Perdomo et al. 2003).
Section 2.12. TVOC and VOC Detection Methods
Direct-reading tubes
Direct-reading tubes contain chemicals that react with certain individual
VOCs to produce a color change. A fixed volume of air is drawn through the tube
by means of a hand pump. The length of stain observed is proportional to the
volume of air sampled and the concentration of VOCs. The method was
developed for the industrial environment and is only marginally suitable for use in
the office environment because of the much lower VOC concentrations usually
30
found there. The method may, however, be useful for screening purposes.
Sensitivities are in the parts per million range.
Passive badges
Passive organic vapour samplers are available with sensitivity levels in
the range of sub-parts per million. These samplers employ charcoal or another
medium as an adsorbent and use sampling periods of eight (8) hours to one (1)
week. The sampler is sent to a laboratory for analysis and provides average
concentration.
Canisters
A sampler consisting of a prefilter, pump, flow controller, and/or flow
restrictor, may be added advantage of container sampling over sorbent methods
which include: (1) whole-air sampling; (2) no breakthrough of target compounds;
(3) no thermal or solvent desorption necessary; (4) multiple aliquots for replicate
analysis, and; (5) time-integrated samples can be obtained by using controlled-
flow pumps with bags or metal containers. The principle disadvantages of using
canisters are the high initial cost and complex analytical techniques.
Active sorption/chemical analysis
Active sorption methods employ tubes packed with a sorbent that traps
the VOCs when air is pumped through the tubes. Sorbents include organic
polymer resins, such as Tenax, XAD, or activated charcoal. The analysis yields
information on the type and quantity of chemicals present.
A wide variety of organic and inorganic sorbents are available for the
collection of ambient VOCs. Inorganic sorbents are rapidly deactivated by water,
making them unsuitable for use in humid environments. Activated charcoal is
widely used by industrial hygienists. The microporous structure of activated
carbon leads to difficulty in recovering some nonpolar compounds. The
31
advantages over charcoal of the newer sorbent materials include higher
sensitivity, absence of a solvent peak and a reduced effect of humidity on
retention volumes
Flame ionization detectors
In the flame ionization detector (FID) method of measuring TVOC,
chemicals in air are burned to produce ionized products that generate a current
in proportion to the concentration. The ionization process is non-specific, and the
result is displayed in real time. Like photoionization detectors, FIDs are useful for
qualitative survey work, such as source location during a walkthrough and the
identification of sampling points. The variability in response is much less for the
FID than for the PID. Also, a greater number of VOCs are detected by the FID
method. Several instruments combine a FID for screening with a portable gas
chromatography (GC) unit for more detailed analysis and specific compound
quantization.
Infrared detectors
Infrared detectors are direct-reading instruments suitable for monitoring
individual VOCs. The variable-wavelength models can be adjusted to scan for
several different VOCs. The sensitivity is in the parts per million and sub-parts
per million range but is not as good as that of a GC, and there can be a problem
with interferences when several VOCs are present together. Direct-reading
instruments such as PID, FID, and infrared detectors can be operated over
several hours or several days with chart recorders and external or internal data
loggers to yield concentration profiles over time.
Photoionization detectors
Photoionization detectors (PIDs) are direct-reading instruments that
detect airborne chemicals by first breaking them into electrically charged
32
fragments by means of an ultraviolet (UV) lamp, then detecting the fragments
(ions) on a metal screen. The number of VOCs that can be detected increases
as the lamp’s UV energy increases. Note that identification of the individual
chemicals present is not possible.
In this chapter, the literature review of the study has been presented. Scientific
books, professional scientific published literature, and scientific electronic pages were
searched and consulted. In the next chapter, the methodology and the research
procedure for this investigation will be presented.
33
Chapter Three
Methodology
Section 3.01. Introduction
The purpose of this research was to investigate the TVOC concentration levels
from indoor and outdoor air in elementary public schools of Puerto Rico. The intention
from these exploratory findings was to determine if there were detectable limits of TVOC
and if these levels exceed the scientific literature guidelines resulting in poor air quality
that may cause health problems to students and school personnel. The aim of this
research is to serve as a base study for other investigations and monitoring programs
regarding the detection and the comparison of TVOC levels indoors and outdoors in
schools of Puerto Rico since these investigations have not been done before.
Section 3.02. Research design
The study design of this research was constructed with a quantitative focus. A
quantitative study uses data collection to test a hypothesis with numeric measurement
and a statistical analysis (Hernandez et al. 2006). This air quality lead study consists of
researching TVOC levels in the air indoors (regulated by Occupational Safety and Health
Administration (OSHA)) and outdoors (regulated by the Environmental Protection
Agency (EPA) and by the Environmental Quality Board (EQB) of Puerto Rico) of the
school, a topic which has not been studied in public schools of Puerto Rico and compare
them with the literature guidelines since neither OSHA, nor the EPA nor the EQB of
Puerto Rico do not have TVOC air guidelines.
The Municipality of Caguas was chosen for the study for various reasons. Firstly,
Caguas is one of the cities in Puerto Rico that has a high incidence of asthma and other
respiratory diseases (Ramo 2003). Also, this Municipality was chosen because the US
EPA Air Emission Source data indicates that in the year 2002, Caguas was among the
33
34
highest municipalities in Puerto Rico with high VOC air emissions (see Appendix 5).
Since the Municipality of Caguas is a valley it can be susceptible to a phenomenon
called thermal inversion. Thermal inversion occurs when a layer of warm air settles over
a layer of cooler air that lies near the ground. The warm air holds down the cool air and
prevents pollutants from rising and scattering (Cork Harbour Alliance for a Safe
Environment 2008). In other words, it is a weather condition in which cool air is trapped
close to the ground instead of rising (EPA 2002b). When atmospheric thermal inversion
occurs, gases and particles precipitate together with the humidity of air, reaching great
concentrations, therefore, what before could be a dispersed with the wind, will remain
deposited (Ruschi 2007).
Educational Public Schools were chosen for TVOC air determination because as
stated in chapter one, school provides a major environment for children away or apart
from their home and children are among the most vulnerable in terms of exposure to
pollutants in air. Children and adults breath the same amount of air (0.3 L/min), but
children face even greater environmental risks than adults due to the fact that their
immune systems are still developing, and because they have a lower body weight, thus
breathing a relative greater volume of air as compared with adults (AQS 2008). This
results in a higher body burden of air pollutants than that obtained by adults for the same
exposure concentration of pollutants. This is magnified to a larger degree for those
children who suffer from asthma and are spending a significant amount of time indoors
(AQS 2008).
Section 3.03. Population selection
The schools in this municipality are divided in two districts: Caguas I and Caguas
II, by the Department of Education of Puerto Rico. The district in this study was selected
at random resulting in the Caguas II District. This District has a total of eleven (11)
schools (see Appendix 8). Of Caguas II District, a total of six (6) are rural schools
35
representing a 54.5% of all Caguas II District, and five (5) are urban schools
representing a 45.5% of all Caguas II District. All urban and all rural schools in this
District have common surroundings. All rural schools in this district are situated in front
or next to a main road, they all have vegetation and they all are next to urbanizations.
All urban schools are situated in the inner-city next or closed to traffic areas and main
roads. A representative random sample of rural and urban schools was obtained to
conduct the study. The representative samples of urban and rural elementary public
schools constituted of 33% and 40% respectively of total schools of the District. Of
these schools, the first grade classroom was randomly selected for the study to uniform
school grade variables of the research in all the schools.
The inclusion compliance requirements to be able to participate in this research
were: the school had to be in the public school system of Puerto Rico, it had to be an
elementary public school of Caguas II District in the Municipality of Caguas Puerto Rico,
and the school had to have a first grade classroom.
Section 3.04. Instrumentation
Wind velocity was taken using a digital anemometer specifically a Mini Thermo-
Anemometer Model 45158 form Extech® Instruments (accuracy +/- 3%). The
temperature and relative humidity were taken using Q-Trak® Plus Model 8552 IAQ
Monitor. The temperature measurements were registered by the instrument with a
thermistor sensor with a range of 0 to 50°C (±0.6°C) with a resolution of 0.1°C. The
relative humidity measurements were registered by the instrument by a thin-film
capacitive sensor with a range of 5 to 95% (± 3%) with a resolution of 0.1%.
TVOC air measurements were taken using a photoionization detector which has
been used in other air quality investigations (Coel-Roaback 2004, Wilson et al. 2007,
U.S. Department of Health and Human Services 2005, Massachusetts Department of
Public Health 2005, Okoroanyanwu et al. 2004, Anderson et al. 2002, New Jersey State
36
Department of Environmental Protection 1999, The City of New York Department of
Health and Mental Hygiene 2003, The Minnesota Department of Health 2004). The
photoionization detector used (PID) was a PID Monitor model PGM-7240 MiniRae®
2000 from RAE Systems Inc (accuracy +/- 10% of reading) (see Appendix 9). Screening
for TVOC was conducted with a photoionization detector (10.6 eV lamp) which is the
lamp that most VOC ionize (see Appendix 10 and 11), which was calibrated (Isobutylene
Gas Calibration) each day prior to use. Peak and steady readings were recorded every
five seconds.
According to the manufacturer, the MiniRae® 2000 is a Photoionization Detector
with standard 10.6 eV or optional 9.8 or 11.7 eV UV lamp. The MiniRae® 2000 is a
durable, lightweight (19.5 oz., including the battery pack), handheld detector designed
for continuous monitoring of dangerous environments for VOCs at ppb levels. Alarm
levels can be preset for low, high, short-term exposure limit (STEL), and the time
weighed average (TWA) levels. There is an audible alarm as well as a visual flashing
red LED, along with the direct ppb display readout. The detector also has point data
logging capability for post event downloading to a personal computer.
The MiniRae® 2000 uses a dual channel PID and an electrodeless discharge
ultra-violet (UV) lamp as the high-energy photon source. The built-in sample pump
draws in the vapor sample at a nominal flow rate of 400 cc / min. The sample passes by
the UV lamp where it is photoionized enabling the electrons to be detected as current by
the photo-multiplier sensor. The instrument uses the sensor readings to calculate the
gas concentrations based on a known response factor derived from a referenced
calibration gas. The MiniRae® 2000 was evaluated in its “Hygiene” mode where the
monitor runs continuously and the LCD displays instantaneous readings. The
instrument can operate on four AA batteries or the rechargeable Nickel Metal Hydride
37
battery pack. The unit has a built-in battery-charging feature that can operate the
instrument and recharge the battery pack using 110V AC.
Calibration instructions were followed according to the MiniRae® 2000 Operation
and Maintenance Manual. Calibration allows the detector to display the detected sample
concentration in parts per billion (ppb) units equivalent to a 10,000 ppb isobutylene
calibration (span) gas. The startup procedure takes approximately five minutes and the
instrument was allowed to stabilize before the calibration. The calibration procedure
requires setting the detector baseline zero point by challenging the unit with either zero
air or the conditioned air of the agent generation system. Then the detector is
challenged with the calibration gas to set the sensitivity span of the instrument. This
means setting the instrument to read 10,000 ppb when challenged with the 10,000 ppb
isobutylene. Once this is set, the instrument is ready for use.
Section 3.05. Data collection procedure
In order to conduct this research in Caguas II District of the Municipality of
Caguas Puerto Rico, it was necessary to obtain authorization from the Department of
Education of Puerto Rico. This authorization was granted in January 28, 2008, by the
Secretary of Educational Planning and Development of Puerto Rico’s Department of
Education. As part of the compliance, an agreement was established with the
Department of Education, that the participating schools names will be kept anonymous
during the research.
As part of the requirement of the School of Science and Technology of the
Universidad del Turabo, the Institutional Review Board (IRB) and Health Insurance
Portability and Accountability Act (HIPAA) Certifications were obtained. The Compliance
Office of the Universidad del Turabo, after reviewing the research proposal, indicated
that it was not necessary to go through the approval from the Protection Board of Human
38
Beings in Research. After completing the research requirements it was proceeded to
initiate the data collection procedure.
Once the grade was selected at random as the first grade, the total of
representative first grade classroom was studied which constituted at one of the first
grade classrooms in each school studied (this represents a sample ≥ 33% of first grade
classrooms in each school studied). To be able to keep the schools anonymous as
requirement by the Department of Education of Puerto Rico, the schools were classified
as 001,002, 003 and 004.
3.05.1. Data Recollection Procedure Phase One
This research was conducted in two phases. The first phase of the study was
conducted in the month of February 2008. Each school was monitored for two days, one
day for each air sample (one day for indoor sample and one day for outdoor sample),
due to instrumentation availability. According with environmental engineers Nelson
Moreno and Israel Matos from the Environmental Quality Board (EQB) of Puerto Rico
and Francisco Claudio form the Environmental Protection Agency (EPA) of Puerto Rico,
if the research does not contemplate comparing the impact of a known emission source
in the school, it is not necessary to take indoor and outdoor samples at the same time
(personal communication March 24, 2008). Since the base of this research was to study
the environmental conditions inside and outside the classroom and not the impact of a
known emission source we can obtain the TVOC data from indoor and outdoor samples
in different days.
Indoor air samples were positioned at the back of the classroom as per stated by
the Department of Education of Puerto Rico to minimize student distraction. If the
school had more than one first grade classroom, the Director of each school had the
authority by the Department of Education of Puerto Rico to choose in which classroom
the measurements would take place. All of the outdoor air samples were taken near the
39
front of the schools in favor of wind direction. The position placement of the instrument
at the back of the classroom and in the outside was indicated by the Director of each
school as required by the Department of Education of Puerto Rico. Because of this
reason, the instrument height position varied from approximately 0.3 to 2 m. The TVOC
were measured for a period of approximately eight (8) hours monitoring to cover school
hours. For the duration of air measurements, indoor and outdoor temperature and
relative humidity were obtained. Wind velocity range was obtained at the initial and
finalization of TVOC measurements in each school at each sample collection. Also, the
quantity of total students and personnel and the quantity of total students and personnel
with respiratory conditions of the total of first grade level in each school was obtained
directly from each Director of the school studied. This data was collected to know how
many children and adults can have possible respiratory health problems in schools if
TVOC levels exceed the literature guidelines.
In any air pollution prediction procedure, local topography and meteorological
events, such as temperature, pressures, and wind velocity, play significant roles (Lee et
al. 2006). The air pollutant concentrations and meteorological variable measurements
provide basic data for air pollution modeling and prediction period. To be able to quantify
the interpretation of air quality observations, it is required to obtained information of the
atmospheric characteristics for the study site. With this purpose the general data for the
meteorological conditions throughout the month of February 2008 were obtained from
the Meteorological Assimilation Data Ingest System (MADIS) Caguas Station. MADIS is
dedicated toward making value-added data available from the National Oceanic and
Atmospheric Administration's (NOAA) Earth System Research Laboratory (ESRL) Global
Systems Division (GSD) (formerly the Forecast Systems Laboratory (FSL)). The
purpose of MADIS is to improve weather forecasting by providing support for data
40
assimilation, numerical weather prediction, and other hydro meteorological applications
(NOAA 2007a, NOAA 2007b, LeMone 2006).
3.05.2. Data collection procedure Phase Two
The second phase of this research was conducted in September of the same
year, 2008. This phase was performed taking in consideration the TVOC data obtained
in phase one. Because of the previous results in the second phase of this research, only
one school of all the schools studied in phase one was chosen. This 004 school based
on the data recollected in phase one seemed to have this distinctive trait. For that fact,
the school 004 was monitored for eight days, altering TVOC measurements for indoor
and outdoor air samples; this is, one day for indoor sample then one day for outdoor
sample, due to instrumentation availability.
As in phase one, the Director of the school had the authority by the Department
of Education of Puerto Rico to choose in which first grade classroom the measurements
would take place. The position placement of the instrument at the back of the classroom
and in the outside was indicated by the Director of the school as required by the
Department of Education of Puerto Rico. Because of this reason, the instrument height
position varied from approximately 0.3 to 2 m. All of the outdoor air samples were taken
near the front of the schools in favor of wind direction. The TVOC were measured for a
period of approximately eight (8) hours monitoring to cover school hours for a total of
eight (8) air samples (four (4) indoor air samples and four (4) outdoor air samples).
According with environmental engineers Nelson Moreno and Israel Matos from the
Environmental Quality Board (EQB) of Puerto Rico and Francisco Claudio form the
Environmental Protection Agency (EPA) of Puerto Rico, if the research does not
contemplate comparing the impact of a known emission source in the school, it is not
necessary to take indoor and outdoor samples at the same time (personal
communication March 24, 2008).
41
For the duration of air measurements, indoor and outdoor temperature, relative
humidity and pressure were obtained. Also, the quantity of total students and personnel
and the quantity of total students and personnel with respiratory conditions of the total of
first grade level in the school was obtained directly from the Director of the school
studied. This data was collected once again to know how many children and adults can
have possible respiratory health problems in school if TVOC levels exceed the literature
guidelines, since the environmental agencies that regulate indoor and outdoor air quality
in Puerto Rico do not have a TVOC guidelines.
Section 3.06. Data analysis
A descriptive statistical analysis was prepared using the statistical analysis
program Minitab®. The average of each school, the standard deviations, and
maximums and minimal TVOC levels were obtained and determined. To be able to
grasp a global analysis of all the schools, a descriptive statistical analysis was
performed; a normality test and a variance test were completed to obtain the p-value
which is a probability, with a value ranging from zero to one. Since these statistical
analysis tests were not normal (p-value<0.05) giving a p-value = 0.010 and did not have
homogeneity (p-value<0.05) giving a p-value = 0.000, non parametric tests were
prepared. Non parametric tests in its majority are based in data organization and do not
require population normality. A Mann-Whitney statistical test was done given that of
independent samples, which is used when two independent samples of populations want
to be compared; it is an alternative test to the t test. The hypotheses used for this test
were: Null Hypothesis (H0): medianIndoor = medianOutdoor; Null Hypothesis (H0): Indoor
(medianRural = medianUrban); Null Hypothesis (H0): Outdoor (medianRural = medianUrban).
Also a statistical Kruskal-Wallis test was used to compare more than two groups; this is
an alternative test to the F test. The hypotheses used for this test were: Null Hypothesis
(H0): Indoor (medianSchool001 = medianSchool002 = medianSchool003 = medianSchool004);
42
Alternative Hypothesis (H1): at least one school differs; Null Hypothesis (H0): Outdoor
(medianSchool001 = medianSchool002 = medianSchool003 = medianSchool004); Alternative
Hypothesis (H1): at least one school differs.
43
Chapter Four
Results
Section 4.01. Phase One of the Research
The schools of the Municipality of Caguas Puerto Rico are divided in two
Districts: Caguas I and Caguas II. Random analysis was prepared using the statistical
analysis program Minitab® to select the district of study resulting in Caguas II and a
representative sample of urban and rural schools were studied. There were a total of
four schools studied, two rural and two urban. These rural and urban schools
constituted a 33% and 40% respectively of the total schools of this District. The school
classification is given by the Department of Education of Puerto Rico, and as petitioned,
the names of the schools were kept anonymous.
As a brief description (see Appendix 13) school 001 is a rural school next to a
church and a baseball park. The school is situated in front of the main road. School 002
is an urban school next to a recreational - sports park and an emergency vehicle center.
This school is also undergoing construction of new facilities. This construction occurs
during school hours form approximately seven in the morning (7:00 am) to four in the
afternoon (4:00 pm). School 003 is also an urban school, situated in the city next to
main roads. Adjacent to this school is a funeral parlor and an automotive repair college.
School 004 is a rural school with roughly little vegetation around. It is located near a
highway in front of a main road and next to it is a food and animal center and a uniform
fabric industry.
Random analysis was prepared using the statistical analysis program Minitab® to
randomly select the school grade resulting in first grade and in order to standardize
research variables, all the samples were taken in the first floor of each school. The
43
44
quantity of students and personnel acquired in each school was given by each school
Director (see Table 4.01).
Table 4.01. Total of first grade students and first grade personnel in each school
studied.
School
Total of fist grade students Total of first grade personnel
001 42 4
002 85 13
003 38 4
004 30 2
Because VOC’s can cause respiratory irritation we obtained the percentage total
of all the students and personnel of the first grade that had respiratory conditions in the
schools (see Table 4.02). This data was given by the Director of each school studied.
Of all the schools studied school 004 had the highest percent of first grade students and
personnel with respiratory conditions.
45
Table 4.02. Percentage of first grade students and personnel with respiratory conditions.
School
% Total of first grade students and first grade personnel
with respiratory conditions
001 15.2
002
13.3
003
15.8
004
34.4
To be able to compare indoor and outdoor TVOC levels, we obtained the
meteorological data for Caguas, Puerto Rico from the Meteorological Assimilation Data
Ingest System (MADIS) Caguas Station. MADIS data indicate that outdoor
meteorological conditions in this municipality do not fluctuate much; daily or weekly
during the month of February 2008 (see Appendices 14 and 15). We can note that the
general meteorological conditions during the days of air quality measurements in the
schools studied are approximately the same. This information suggests that the
meteorological conditions at the schools and in the classrooms during the sample days
should not affect the TVOC levels because meteorological conditions do not vary
markedly daily or weekly. Because of this finding, indoor and outdoor levels of TVOC
can be compared even if there is no known VOC source.
During the sampling, the temperature and relative humidity were obtained and as
presented below (see Tables 4.03 and 4.04), we can observe that both the temperature
and relative humidity are higher outdoors than indoors.
46
Table 4.03. Temperature data obtained for each school for indoor and outdoor samples.
School Type of
School
Indoor Temperature (°C)
Outdoor Temperature (°C)
Mean*
(± SD)
Max
Min
Mean*
(± SD)
Max
Min
001 Rural 25 ± 1 27.1 22.8 26 ± 2 28.9 21.7
002 Urban 22.8 ± 0.8 25.9 22.4 27 ± 1 28.9 24.0
003 Urban 27 ± 1 28.9 24.9 32 ± 4 41.2 22.4
004 Rural 27 ± 2 30.1 23.6 30 ± 3 40.3 27.3
*n = 29
Table 4.04. Percentage of relative humidity data obtained for each school for indoor and
outdoor samples.
School Type of
School
Indoor Relative Humidity
(%)
Outdoor Relative Humidity
(%)
Mean*
(± SD)
Max
Min
Mean*
(± SD)
Max
Min
001 Rural 75 ± 5 85.3 66.1 64 ± 10 80.8 49.2
002 Urban 61 ± 3 67.9 56.9 63 ± 8 78.7 52.7
003 Urban 62 ± 8 81.1 51.8 51 ± 12 81.1 31.2
004 Rural 61 ± 12 82.3 42.9 47 ± 7 56.6 29.3
*n = 29
47
As for indoor ventilation in the schools (see Table 4.05), schools 001 and 003
have cross or natural window ventilation and schools 002 and 004 have artificial
ventilation (air conditioning system). Ironically, one of each urban and rural schools
studied had one school with natural window ventilation and one school with artificial
ventilation. The Director of each school had the authority (by the Department of
Education of Puerto Rico) of choosing which first grade classroom the investigation
would take place (if there was more than one first grade classroom), which meant that
there was no control over the indoor ventilation variable in this study. We can also
observe that wind velocity range is higher outdoor than indoors for all four schools.
Table 4.05. Wind velocity obtained for each school for indoor and outdoor samples.
School Type of
School Type of Ventilation
Indoor (m/s) Outdoor (m/s)
Max Min Max Min
001 Rural Natural Ventilation 0.0 0.0 2.6 0.0
002 Urban Artificial Ventilation/
Natural Ventilation 0.0 0.0 2.0 0.0
003 Urban Natural Ventilation 0.0 0.0 0.8 0.4
004 Rural Artificial Ventilation/
Natural Ventilation 0.5 0.0 1.1 0.3
*With a margin of error = ± 3%.
TVOC measurements are shown in Table 4.06. It can be seen that not all the
schools had detectable TVOC measurements and that TVOC maximum concentration
48
vary from school to school and indoor versus outdoor, which indicates that each school
is unique. When comparing types of indoor ventilation in the classrooms studied in each
school with indoor TVOC measurements (see Table 4.07), it can be observed that higher
peaks were found in classrooms that had artificial ventilation versus the classrooms that
had cross or natural ventilation.
Table 4.06. Summarized indoor and outdoor TVOC results measurements for the
schools studied.
School Type of School
Indoor TVOC (mg/m3) Outdoor TVOC (mg/m3)
Mean*
(±SD)
Max Min Mean*
(±SD)
Max Min
001 Rural 0 ± 0 0.0 0.0 0 ± 0 0.0 0.0
002 Urban 0.0 ± 0.6 47.20 0.0 0 ± 5 76.50 0.0
003 Urban 0.0 ± 0.3 22.07 0.0 0 ± 2 126.88 0.0
004 Rural 18 ± 31 468.91 0.0 5 ± 16 95.16 0.0
*n=5560
49
Table 4.07. Comparison of types of indoor ventilation and TVOC results measurements
for the schools studied.
Type of Ventilation School
Indoor TVOC (mg/m3)
Mean*
(±SD)
Max
Cross or Natural Ventilation 001 0 ± 0 0.0
003 0.0 ± 0.3 22.07
Artificial Ventilation /
Natural Ventilation
002 0.0 ± 0.6 47.20
004 18 ± 31 468.91
*n=5560
When graphing all the TVOC data measurements obtained at each school
individually, which were take every five (5) seconds, we found that no TVOC detection
levels were observed for rural school 001 at indoor and outdoor measurements. For
urban school 002, TVOC indoor measurements were also below the detection limit
except for one measurement early in the morning at 7:44 am before classes started with
a concentration of 47.20 mg/m3. For this school outdoor measurements were different.
Early in the morning from 8:10-8:25 am high measurements were observed with the
highest peak at a concentration of 76.50 mg/m3. In the afternoon it can be observe
some random TVOC measurements at around 13:00 - 14:20 pm. TVOC measurements
obtained for this urban school showed differences in the outdoor and indoor sample
measurements for this school (see Figure 4.01).
50
Figure 4.01. Concentration of TVOC versus time for school 002 for indoor and outdoor
TVOC data (n=5560).
For the majority of indoor and outdoor measurements for urban school 003 were
also below the detection limit except for some measurements late in the afternoon. For
the indoor sample there was a measurement at 15:34 pm after classes had concluded
that corresponds to a concentration of 22.07 mg/m3. For the outdoors measurements for
the same school, there were various measurements also in the late afternoon starting at
around 15:28 pm – 15:35 pm after classes had ended with the highest peak at a
concentration of 126.88 mg/m3. This is the highest TVOC concentration measurement
51
for an outdoor sample of all the schools studied. Figure 4.02 shows the chart of TVOC
measurements obtained for school 003 and the differences in the outdoor and indoor
sample measurements can be observed predominantly in the late afternoon for this
school.
Figure 4.02. Concentration of TVOC versus time for school 003 for indoor and outdoor
TVOC data (n=5560).
Of all the schools studied, rural school 004 showed the highest TVOC
concentration for indoor measurements with a peak of 468.71 mg/m3 at around 7:43 am.
For this school, a variety of measurements can be observed in the morning both for
indoor and outdoor samples. The highest concentration measured for the outdoor
sample of this school was 95.16 mg/m3 at around 8:00 am. Also in the late afternoon
there was a TVOC measurement of 9.65 mg/m3 at around 15:24 pm. Figure 4.03 shows
52
the chart of TVOC measurements obtained for school 004 and we can observe the
differences in the outdoor and indoor sample measurements predominantly in the
morning.
Figure 4.03. Concentration of TVOC versus time for school 004 for indoor and outdoor
TVOC data (n=5560).
Statistical analyses were done in the statistical computer program MiniTab®.
The statistical tests done were nonparametric because the data obtained for the
concentration of TVOC indoors and outdoors were not normal (“p-value” = 0.010) and
did not had variance homogeneity (“p-value” = 0.000). The Mann-Whitney test was done
to compare two populations using independent samples (“p-value” = 0.000). This is an
alternative test to the t test to be able to compare two averages using independent
samples. The hypotheses used for this test were: Null Hypothesis (H0): medianIndoor =
53
medianOutdoor; Null Hypothesis (H0): Indoor (medianRural = medianUrban); Null Hypothesis
(H0): Outdoor (medianRural = medianUrban). Also a statistical Kruskal-Wallis test was used
to compare more than two groups; this is an alternative test to the F test. The
hypotheses used for this test were: Null Hypothesis (H0): Indoor (medianSchool001 =
medianSchool002 = medianSchool003 = medianSchool004); Alternative Hypothesis (H1): at least
one school differs; Null Hypothesis (H0): Outdoor (medianSchool001 = medianSchool002 =
medianSchool003 = medianSchool004); Alternative Hypothesis (H1): at least one school differs.
Section 4.02. Phase Two of the Research
This phase was performed taking in consideration the TVOC data obtained in
phase one. TVOC levels obtained in phase one indicated that TVOC concentration
levels seem not to be an ongoing problem in all the elementary public schools studied in
Caguas District II although some levels are higher than the scientific guidelines for
TVOC in the air, due to the fact that most of the time there were no detectable levels of
TVOC that could cause any potential health problems in children or in school personnel
(>25 mg/m3). However, of all the schools studied school 004 in phase one was chosen
for a more extensive study because this school seemed to have this distinctive trait
compared to all the other schools studied having the highest TVOC concentration for
indoor and outdoor measurements. For that fact, the school 004 was monitored for total
of eight days altering TVOC measurements for indoor and outdoor air samples; this is,
one day for indoor sample then one day for outdoor sample, due to instrumentation
availability.
As a reminder, school 004 is a rural school with roughly little vegetation around.
It is located near a highway in front of a main road and next to it is a food and animal
center and a uniform fabric industry. Because VOC can cause respiratory irritation we
obtained the percentage total of all the students and personnel of first grade that had
54
respiratory conditions in the schools (see Table 4.08). The quantity of students and
personnel was obtained directly from the Director of the school to be able to know how
many of the first grade students and personnel suffered from respiratory conditions.
Table 4.08. Total of first grade students and first grade personnel and the total
percentage with respiratory conditions in the 004 school studied.
School
Total of fist
grade students
Total of first
grade personnel
% Total of first grade students and first
grade personnel with respiratory
conditions
004 25 1 19.23
This school had only one first grade classroom which uses artificial as well as
natural ventilation. The ventilation mechanism used in the classroom is at the discretion
of the school teacher. The first grade teacher indicated that she used the artificial
ventilation in the morning and natural ventilation in the afternoon during the eight (8)
days research study.
The position placement of the instrument at the back of the classroom and in the
outside was indicated by the Director of the school as required by the Department of
Education of Puerto Rico. Because of this reason, the instruments height position varied
from approximately 0.3 to 2 m. All air measurements (TVOC, relative humidity and
temperature) were measured for a period of approximately 8 hours monitoring to cover
school hours. All of the outdoor air samples were taken near the front of the schools in
favor of wind direction.
55
During the acquirement of TVOC measurements temperature and relative
humidity data was obtained every half hour in the school. It can be observed from Table
4.09 and Table 4.10 that the temperature and relative humidity did not vary much
comparing indoors and outdoors.
Table 4.09. Temperature data obtained for the school 004 for indoor and outdoor
samples.
Day
Indoor Temperature (°C) Outdoor Temperature (°C)
Mean*
(± SD)
Max
Min
(°C)
Mean*
(± SD)
Max
Min
1 32 ± 1 34.1 29.3
2 29 ± 2 32.4 27.1
3 31 ± 4 35.3 30.1
4 29 ± 2 31.4 25.8
5 29 ± 2 31.7 25.9
6 33 ± 4 38.8 24.1
7 30 ± 2 32.7 25.4
8 34 ± 3 38.6 26.9
*n = 17
56
Table 4.10. Percentage of relative humidity data obtained for the school 004 for indoor
and outdoor samples.
Day
Indoor Relative Humidity (%) Outdoor Relative Humidity (%)
Mean*
(± SD)
Max
Min
(°C)
Mean*
(± SD)
Max
Min
1 55 ± 6 67.9 47.2
2 49 ± 2 51.7 43.8
3 65 ± 4 69.2 54.7
4 71 ± 9 86.6 57.8
5 70 ± 8 85.0 57.1
6 54 ± 15 81.5 44.1
7 65 ± 6 78.8 57.7
8 60 ± 2 91.7 49.4
*n = 17
The data obtained for eight days monitoring at this rural school showed basically
the same pattern of detectable levels of TVOC indoors and outdoors samples as in
phase one of this research (see Figures 4.04 and 4.05). For this school, a variety of
measurements can be observed in the morning both for indoor and outdoor samples.
Rural school 004 showed high TVOC air concentration for indoor measurements with a
maximum peaks that fluctuate in the high four hundreds mg/m3 in the morning.
Outdoors, this school showed TVOC air concentrations measurements with maximum
peaks that fluctuate in the high hundreds mg/m3 in the morning (see Table 4.11). When
57
calculating the averages and maximum peaks of the TVOC measurements obtained
from indoor and outdoor air samples it can be observed that both averages and
maximum peak measurements are higher indoors than outdoors (see Table 4.11) as
observed in phase one of this research.
Figure 4.04. Concentration of TVOC versus time for indoor air measurements of school
004 (n=5563).
58
Figure 4.05. Concentration of TVOC versus time for outdoor air measurements of
school 004 (n=5563).
59
Table 4.11. Summarized indoor and outdoor TVOC results measurements for the school
004.
Day
Indoor TVOC (mg/m3) Outdoor TVOC (mg/m3)
Mean*
(±SD)
Max Min Mean*
(±SD)
Max Min
1 18 ± 27 409.04 0.0
2 10 ± 20 183.13 0.0
3 13 ± 26 496.13 0.0
4 10 ± 20 191.56 0.0
5 16 ± 25 475.39 0.0
6 11 ± 21 152.28 0.0
7 16 ± 24 452.38 0.0
8 8 ± 20 179.00 0.0
*n=5563
In this chapter, the TVOC air measurements and the climatological and
meteorological data obtained in the schools studied have been presented. In the next
chapter, the results and findings are discussed. Also in the next chapters are mentioned
the conclusions of this research and recommendations for future air quality
investigations are offered.
60
Chapter Five
Discussion, Conclusions and Recommendations
Section 5.01. Introduction of Discussion
The purpose of this study was to investigate the TVOC concentration levels
indoors and outdoors in elementary public schools of Caguas II District in Puerto Rico
since these studies have never been done before. This environmental air quality
perspective is growing in importance to school systems around the nation, especially as
it is related to the health protection and educational performance of students and
teachers (Berry 2008). It is becoming increasingly recognized that the indoor
environments of schools are directly related to human health, image, self-esteem, and
attitude, all of which affect academic performance (Berry 2008). The idea of this
exploratory research was to serve as a base study for future investigations for the
determination of TVOC levels in the air, in view of the fact that air quality in schools can
have a substantial impact on children’s health.
This study was divided in two phases. Phase one of this research was done in
February of 2008. A representative randomly selected sample of rural and urban
elementary schools of Caguas II District of the Municipality of Caguas Puerto Rico were
studied. TVOC Samples of indoor and outdoor air were taken in a first grade classroom
selected by the Director of each school studied for a period of one day each sample (one
day indoors and one day outdoors). The second phase of this research was done in
September of 2008. Based on the TVOC results of each school from phase one, only
one school was studied for eight (8) days taking in alternation indoor and outdoor TVOC
measurements samples. As part of the limitation in the study, there were delays in
obtaining the information necessary to know the number of student and personnel with
respiratory conditions given by each Director of each school studied. Also, it was difficult
60
61
to obtain information if the students that were absent in the day of sampling was due to
respiratory sickness.
Section 5.02. Discussion of Phase One of the Research
Taking in consideration the surroundings around at the schools studied in
Caguas II District we can observe various air quality situations that can affect the air
quality in the school. Some of these situations are that the schools are located near
main roads, some have construction work going on during schools hours, some have
mold growing on the latches of the roof, and others are next to possible emission
sources such as sewers and auto repair colleges (see Appendix 16). These situations
are common air quality problems that are representative of both urban and rural
elementary public schools of Caguas II District. These sources can emit volatile organic
compound at high concentrations that could exacerbate respiratory conditions among
students and/or faculty members, as stated in the literature review.
When statistically comparing the total of indoor and outdoor TVOC
concentrations of all the schools studied using the Mann-Whitney statistical test, strong
evidence can be found that outdoor concentrations of TVOC are higher than indoors
because the p-value obtained was 0.00 which is less than 0.05. This also can be
observed in the mean TVOC concentrations and its standard deviations obtained in this
research (see Table 4.06). This finding is contrary to air quality investigations found in
the scientific literature were indoor samples are higher than outdoor samples due to
building construction materials (Minnesota Department of Health 2005, Sweet et al.
1992). This finding indicates that for elementary public schools in Caguas II District
indoor TVOC levels will depend on the activities arranged in the classroom or from a
near outdoor source if ventilation is inadequate. Contrary to indoor TVOC levels found
in the schools studied, outdoor TVOC levels will depend on the surroundings near the
school. Due to financial constraints, indoor and outdoor samples could not be obtained
62
the same day which could be considered as a limitation of this study. As for TVOC
determination, there was a characterization limitation in determinating and identifying
which types of VOC constituted the TVOC parameter. Even though limitations were
inevitable, the results obtained in this research are reliable to be able to establish
conclusions in respect to the objective and hypothesis of this research.
When statistically comparing rural and urban schools TVOC concentrations using
the Mann-Whitney statistical test a p-value of 0.00 was obtained which is less than 0.05
indicating that urban schools are more exposed to TVOC air quality problems than rural
schools. This is true for both indoor and outdoor measurement comparison for rural
schools versus urban schools, because all urban schools studied had detectable levels
of TVOC and not all rural schools studied had detectable TVOC levels. However,
consideration should be made when relating exposure with health effects due to type of
VOC characterization and concentration of each VOC that constitutes the TVOC
measurement obtained. With many pollution sources found in urban areas, it may be
difficult to single out which sources could be the possible source causing the problem. A
possible common source could be traffic proximity near the school. Because several
reactive hydrocarbons are formed during combustion and can accumulate in the
atmosphere (Leikauf 2000, Paliulis 2007). The Kruskal-Wallis statistical test for TVOC
indoor and outdoor concentration in schools results were “p-values” of 0.000 which
indicate that at least one school differs for indoor and outdoor sample comparison which
makes every schools studied unique.
The research data obtained for the schools studied indicate that the students are
exposed to air quality problems. As stated by Godwin et al. (2006), IAQ problems may
be exacerbated in schools due to inappropriate landscaping with minimal or poor
drainage, basic and minimal engineered ventilation and if any air conditioning system,
the lack of preventative maintenance, and crowded conditions.
63
Since there are no TVOC environmental agency guidelines for indoor and
outdoor in the US and in PR, a number of international scientific guidelines can be used
to provide some indication as to whether levels measured in the schools are above
desirable limits (Ajiboye et al. 2006, Raw et al. 2004). The indoor air goal
concentrations recommended in 1992 by the National Health and Medical Council
(NHMC) in Australia, is 500ug/m3 (0.5 mg/m3) for TVOC by one hour averaging period
(Brown 1997). A TVOC concentration > 500ug/m3 indicates significant present of
sources. Significant discomfort and headaches are likely if concentrations fall in the
range of 3mg/m3-25mg/m3 (Grimsrud 2004, AERIAS 2007). As for TVOC monitoring by
photoionization detection (PID) (calibrated with isobutylene), the recommended
guidelines are (RAE Systems Application Note AP-212, 2008):
<0.30 mg/m3 normal outdoor air
0.30-0.2 mg/m3 for normal indoor air
>1.15 mg/m3 indicates potential air quality contamination
Comparing TVOC mean concentrations obtained in the schools studied (see
Appendices 14 and 15) with these guidelines, it can be observed that the TVOC average
levels found in schools are between the TVOC limits found in the scientific literature with
the exception of school 004. The TVOC measurements obtained for this school in
particular may indicate potential air quality contamination. But even though the TVOC
mean concentrations levels found in the other schools studied, students and personnel
are still exposed to VOC concentrations because in the scientific literature TVOC
concentrations typically range from 50-1000 µg/m3 over long periods of time but TVOC
levels can reach hundreds of mg/m3 for periods of minutes and hours (European
Collaborative Action 1997, Daisey et al. 2003). A tendency of TVOC measurements
exceeding the scientific literature guidelines can be observed in Figure 5.01 and 5.02.
This VOC exposure could be harmful to human health depending on the type and
64
concentration of the VOC found in the air that constitutes the TVOC parameter detected
at each school. The exposure to TVOC can contribute to exacerbation of respiratory
conditions depending on the type of VOC’s that constitute the Total VOC. Also,
exacerbation of respiratory conditions can occur when the TVOC peaks exceed the
concentration guidelines for a period of time in the air and are inhaled.
Based on the guidelines mentioned above, when comparing indoor and outdoor
maximum TVOC peaks and means concentration measurements in each school studied,
it can be observed that the TVOC measurements tend to be higher outdoors compared
to indoor mean levels and peak value (see Figures 5.01 and 5.02; Appendix 17). These
findings are contradictory to those found in the literature were indoor TVOC
measurements exceed those found outdoors. Although, exception can be found in
school 004 data which demonstrates that there is either an indoor source or there is poor
ventilation exchange with the outdoors. These TVOC measurements in school 004 can
be due to classroom cleaning before classes start and poor ventilation exchange once
the air conditioning unit was turned on. Interestingly this school is the school which has
the highest percentage of respiratory conditions among students and personnel. It is
also the school with the highest TVOC measurement peak among the schools studied
which makes this school the most vulnerable of all the schools studied in terms of TVOC
exposure. As part of the limitations of this research wind direction could not be obtained
which is a constraint if source is wanted to be known.
65
Figure 5.01. Indoor TVOC mean concentrations and maximum peak observed at the
schools studied.
66
-20
0
20
40
60
80
100
120
140
001 002 003 004
Schools
Concentration (mg/m3)
Mean (n = 5560)
Max Peak
Figure 5.02. Outdoor TVOC mean concentration and maximum peak observed in the
schools studied.
Comparing indoor samples with the outdoor sample measurements, in Figures
5.03 and 5.04 we can notice that there is a source or an activity occurring either at the
school or near the school that produces VOC contamination. This can be seen in school
004 where there is a prominent source that is emitting emissions near the school, as
detected in the early morning hours. The TVOC outdoor sources could be a near by
textile industry (54 m distance), a pet shop and animal food center (20 m distance), a
closed propane gas storage facility (1.04 km distance) or even a gasoline station near
by. Indoor TVOC sources could come from outdoor sources when poor ventilation is in
place or from early classroom cleaning practices. Also school 002 has a source near the
school that causes sporadic VOC emissions as seen in the outdoor sample. This VOC
67
source could be the sewers in front of the school that when wind direction and velocity
change, TVOC can be detected. Another source could be a plastic basin close to the
classroom which is used in early morning cleaning process. More comprehensive
studies should be conducted to characterize the volatile organic compounds found in
these schools to further determine the source and potential health effects to the students
and school personnel.
Figure 5.03. Comparison chart for indoor and outdoor TVOC maximum peak
measurements for each school studied.
68
Figure 5.04. Comparison chart for indoor and outdoor TVOC averages for each school
studied (n Indoor and Outdoor = 5560).
Section 5.03. Discussion of Phase Two of the Research
This research was conducted in September of 2008. This phase was performed
taking in consideration the TVOC data obtained in phase one. TVOC levels obtained in
phase one indicated that TVOC concentration levels seem not to be an ongoing
problems in the elementary public schools studied due to the fact that most of the time
there were no consecutive detectable levels of TVOC that could cause any potential
health problems in children or in school personnel (>25 mg/m3). However, there were
still detectable levels in which depending on the source of emission near or at the school
could cause health concerns in the long run if this was a constant emitting source. This
school, school 004, based on the data recollected in phase one seemed to have this
distinctive trait. For that fact, the school was monitored for a total of eight (8) days
69
altering TVOC measurements for indoor and outdoor air samples; this is, one day for
indoor sample then one day for outdoor sample, due to instrumentation availability.
Results indicate that there was not a considerable change observed of the TVOC
air levels detected indoors and outdoors in the school compared to those obtained in
phase one in the month of February, even though there is a seven month difference in
the detection of TVOC air levels. In the figures 5.05 and 5.06, a comparison of indoor
and outdoor maximum TVOC peaks and means concentrations can be observed. The
TVOC air measurements are higher indoors (13mg/m3-18mg/m3) than outdoors
(8mg/m3-11mg/m3). These findings are consistent to those found in the literature were
indoor VOC’s are found in levels in order of magnitude higher than those outdoors.
These results indicate that there is in fact a source next or close to the school that can
become a health concern to students and personnel if and when the TVOC levels
exceed those from the literature guideline (3mg/m3 – 25mg/m3). A more detailed
characteristic study needs to be done in this school in particularly to be able to identify
the source.
70
Figure 5.05. Outdoor TVOC mean concentration and maximum peak observed in the
school 004 for the days studied.
71
Figure 5.06. Indoor TVOC mean concentration and maximum peak observed in the
school 004 for the days studied.
Higher peaks of TVOC indoor air measurements can be attributed to early
cleaning practices in the classroom and poor air exchange ventilation since in the
morning the air conditioning was turned on as soon as class started. However, this
statement should be confirmed with a more detailed characterization research due to the
fact that outdoor TVOC air levels are also observed in the morning but in less
concentration. This can be observed comparing indoor samples with the outdoor
72
sample average measurements and maximum concentration measurements (see
Figures 5.07 and 5.08).
Figure 5.07. Comparison chart for indoor and outdoor TVOC averages for school 004
(n Indoor and Outdoor = 5563).
73
Figure 5.08. Comparison chart for indoor and outdoor TVOC maximum measurements
for school 004 (n Indoor and Outdoor = 5563).
Section 5.04. Conclusion
The objective of this study was to investigate the total volatile organic
compounds (TVOC) levels upon indoor and outdoor air quality in a representative
sample of elementary public schools of the Caguas II District Municipality of Caguas,
Puerto Rico. Since TVOC levels detected in scientific literature research are attributed
to building material construction such as wood and gypsum board, we would expect no
TVOC levels to exceed in building schools in Puerto Rico because they are made of
concrete. However, baseline measurements of this research compared to TVOC
74
guidelines from the scientific literature show that total volatile organic compounds do not
seem to be an on-going problem in elementary public schools of Caguas II District
because for most of the time of sampling measurements, there were no detectable
levels of TVOC that could cause any potential health problems in children or in school
personnel (>25 mg/m3). Nevertheless, there were still detectable levels in which
depending on the source of emission near or at the school and its emission or off
gassing of TVOC could cause health concerns in the long run if this was a constant
emitting source or if a student or school personnel has an existing respiratory problem.
These TVOC air measurements were compared to those from the scientific literature
guidelines because there are no TVOC indoor or/and outdoor guidelines from
environmental agencies in the United States nor in Puerto Rico.
For rural school 004 of this research seem to have this distinctive trait since there
was a continuous TVOC air detection during every air sample taken at this school.
Every outdoor and indoor TVOC air measurement sample seems to have the same
pattern of high TVOC peaks early in the morning decaying close to midday. Indoor
emission source could come from cleaning products due to early cleaning practices in
the classroom and outdoor emission sources could come from nearby industries or
transportation emissions. As it can be seen, the characteristics of VOC concentrations
in ambient air depend on the strength of each emission source close to the schools
studied. However, continuous measurements should be made integrated with a risk
assessment study, to determine any health related effects, so this conclusion may be
premature.
A more detailed environmental research with the characterization of VOC in air
would provide first hand information needed to define a correlation between respiratory
diseases and air quality in schools. The study’s limited explanatory power suggest that
variables omitted from the study due to data constrains (e.g. characterization
75
measurements because of lack of instrumentation) are likely to be better predictors of
severe incidents of respiratory diseases among students.
Section 5.03. Recommendations
An organized management plan or cleaning program will contribute to a significant
improvement. This should include:
1. Facility planning – establishing procedures and guidelines for building
maintenance, appropriate scheduling of these activities and use of low
emitting cleaning products. Cleaning is the most fundamental management
strategy. Classroom cleaning should be arranged late in the afternoon after
classes have ended, so VOC cleaning products emissions could dissipate
overnight
2. Baseline monitoring – two (2) times a year; example prior to opening school
each semester.
3. Good communication plan between school personnel.
As identified in this research a more detailed identification of VOC study should
be conducted especially in school 004, to be able to characterize if the concentrations of
VOCs detected can cause health problems. The availability of such data will allow the
research community to better quantify the human health risk associated with some of the
most dangerous indoor environmental contaminants. Protection of human health
against disease and injury caused by toxic chemicals in the environment is the ultimate
goal of risk assessment and management. The protection of children against toxic
chemicals in the environment will require fundamental and far-reaching revisions of
current approaches to surveillance, toxicity testing, and risk assessment.
From a public health’s stand point, because low levels of ambient air pollution
appear to have exerted a modest impact in terms of prediction, this finding underscore
the importance of delineating the VOC contribution of air quality. Future investigations
76
will be valued not merely as academic but as means for resolving and improving air
quality. Given that the General Accounting Office of the United States concluded that
one in five schools has IAQ problems, and given that thousands of schools are slated for
construction or renovation within the next five (5) years, the need to identify simple,
effective, energy-efficient ways of resolving these IAQ problems is both obvious and
significant (Bayer et al. 2007).
For VOC monitoring, as should be any air quality data, the instrumentation or
method response should be timely, continuous, should have high sensitivity and
accuracy, and the instrument should be field operable or should be accompanied or
coupled by different methods or instrumentation that are field operable for
complementation. The best strategy for improving air quality is through the identification
and control of pollutants at their source. The ideal circumstances would be the
identification of the contaminants, and so, an environmentally friendly solution.
77
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Appendices
90
91
Appendix One
Caguas, Puerto Rico
Figure A1. Map location of the Municipality of Caguas in Puerto Rico.
Source: Puerto Rico Planning Board 2007.
92
Appendix Two
Secondary production of urban smog oxidants by photochemical reactions in the
atmosphere
Atmospheric oxidant production:
1. NO + VOC → NO2 (nitrogen oxide)
2. NO2 + UV→NO + O (nitric dioxide + atomic oxygen)
3. O + O2 → O3 (ozone)
4. NO + VOC → PAN, etc. (peroxyacetyl nitrate)
Net results:
NO + VOC + O2 + UV→ O3, PAN and other oxidants
Source: Cunningham et al. 2003.
93
Appendix Three
Asthma prevalence in the year 2000
Figure A3. Map of weighted prevalence of asthma in the continental USA and its
territories during 2000.
Source: Perez-Perdomo et al. 2003.
94
Appendix Four
Volatile organic compound sources
Table A4. Typical sources of air pollutants
Outside Sources
Polluted Outdoor Air: Pollen, dust, fungal, industrial and vehicle
emissions.
Nearby Sources: loading vehicle parking or loading, odours
from dumpsters, unsanitary debris or building exhaust
near outdoor air intakes.
Underground sources: soil gases, pesticides, leakage from
underground storage.
Building Equipment: Emission from office equipment, cleaning
processes, atria planters and other wet areas.
Component/
Furnishings
Components: microorganisms growing on soiled or water-
damaged materials, materials containing volatile
organic compounds, inorganic compounds, or damaged
asbestos, materials that produce particles or fibers.
Other
Indoor
Sources
Copy/print areas, food preparation/eating areas, cleaning
materials, emission form trash, pesticides, odours and
volatile organic compounds from paint, sealants or
adhesives; markable felt pens, pests, renovation
activities.
Source: Ministry of National Health and Wealfare 1995.
95
Appendix Five
Volatile organic compounds emission by source sector in 2002
The chart below shows the national summary of volatile organic compounds (VOCs)
emissions by source sector in the year 2002.
Figure A5.01. National volatile organic compounds emission by source sector in 2002.
Source: EPA 2002.
96
The map below shows relative emission density (tons per square mile) by
dividing counties into three groups, with the darker-shaded counties having higher
relative emission density.
Figure A5.02. Volatile organic compounds emission by municipalities of Puerto Rico in
2002.
Source: EPA 2002.
97
The graph below shows state-level emissions in Puerto Rico grouped by major
source sectors. The same information is also available for the individual counties below.
Figure A5.03. Volatile organic compounds emission by source sector in Puerto Rico in
2002.
Source: EPA 2002.
98
The graph below show’s relative VOC emission density (tons per square mile) in
Caguas, Puerto Rico.
Figure A5.04. Volatile organic compounds emission by source sector in Caguas, Puerto
Rico in 2002.
Source: EPA 2002.
99
Appendix Six
Hazardous air pollutants of greatest concern
Table A6. Hazardous air pollutants of greatest concern for exposure and health effects.
aCompounds suspected of inducing or exacerbating asthma.
Source: EPA 2000
Acetaldehydea Formaldehydea
Acreolina Hexachlorobenzene
Acrylonitrile Hydrazinea
Arsenic compounds Lead compounds
Benzenea Manganese compoundsa
Berylium compounds Mercury compounds
1,3-Butadiene Methylene chloride
Cadmium compoundsa Nickel compoundsa
Carbon tetrachloride Perchloroethylene
Chloroform Polychlorinated biphenyls
Chromium compoundsa Polycyclic organic matter
Coke oven emissionsa Propylene dichloride
1,3-Dichloropropene Quinoline
Dioxin 1,1,2,2-Tetrachloroethane
Ethylene dibromide Trichloroethylene
Ethylene dichoride Vinyl chloride
Ethylene oxidea
100
Appendix Seven
Volatile organic compounds emission sources
Table A7. Volatile Organic compounds emitted from building
materials and interior furnishings.
Source: Crinnion 2000.
Source Pollutant Emitted
Adhesives Alcohols
Amines
Benzene
Formaldehyde
Terpenes
Caulking Compounds Xylenes
Alcohols
Alkanes
Amines
Fomaldehyde
Methylketone
Xylenes
Benzene
Carpeting Alcohols
Alkanes
Formaldehyde
4-Methylbenzene
Styrene
Particle Board Alcohols
Alkanes
Amines
Benzene
3-Carene
Formaldehyde
Terpenes
Toluene
Tile and linoleum
Floor coverings
Wall coverings
Acetates
Alcohols
Alkanes
Amines
Benzene
Formaldehyde
Methyl styrene
Xylenes
Paints, stains,
varnishes
Acetates
Acrylates
Alcohols
Alkanes
Amines
Benzenes
Formaldehyde
101
Appendix Eight
List of elementary public schools in Caguas II District
Table A8. Total number of elementary public schools of Caguas II District, Puerto Rico.
Schools Zone Physical Address
(Caguas, PR 00725)
SU Mercedes Palma Rural Bo. San Salvador
SU Sandalio Marcano Rural Bo. Tomas De Castro 1
Bunker Rural Bo. Cañaboncito
Cipriano Manrique Rural Bo. Borinquen
Ramón Brugeras Rural Bda. Villa Esperanza
Cornelio Ayala Rural Bo. Borinquen
Concepción Méndez Cano (Conchita) Urban Urb. Turabo Gardens
José Mercado Urban Urb. Mariolga
Ave. Luis Muñoz Marin
Luis Munoz Rivera Urban Final Calle Muñoz Rivera
Paula Mojica Urban Urb. Villa Turabo
Rosa C. Benítez Urban Primera Sección
Urb. Villa del Rey
102
Appendix Nine
Instrumentation used
Figure A9. MiniRae® PID 2000 Instrumentation used for TVOC measurements.
Source: RAE Systems 2001.
103
Appendix Ten
Volatile Organic Compounds Detected By PID with a 10.6 eV Lamp
(Source: RAE Systems Inc.)
Acetaldehydea (ethanal); C2H4O
Acetic Anhydride (Acetic Acid)
Acetone
Acroleina (2-propenal); C3H4O
Acrylamidea; C3H5NO
Acrylonitrilea (2-propenenitrile); C3H3N
Allyl Alcohol
Allyl Chloride
Allyl Glycidyl Ether
Aminopyridine
Amyl Acetate
Amyl Alcohol
Anilinea (aminobenzene); C6H7N
Anisidine
Anisole
Benzenea; C6H6
Benzyl Alcohol
Benzyl Chloridea (a-chlorotoluene);
C7H7Cl
Bromoforma (tribromomethane); CHBr3
n-Bromopropane
Butadienea; C4H6
Butoxyethanol
Butyl Acetate
Butyle Acrylate
Butyl Alcohol
Butylamine
Butyl Cellosolve
Butyl Glycidyl Ether
Butyl Mercaptan
Camphor Vapor
Carbon Disulfidea; CS2
Cellosolve
Chloroacetaldehyde
Chloroacetophenone
Chlorobenzenea; C6H5Cl
Chloroprenea (2-chloro-1,3-butadiene);
C4H5Cl
Cresola; C7H8O
Crotonaldehyde
Cumenea (isopropylbenzene); C9Hl2
Cyclohexane
(aCompounds regulated by the US Environmental Protection Agency)
104
Continuation of Volatile Organic Compounds Detected By PID 10.6 eV Lamp
Cyclohexanol
Cyclohexanone
Cyclohexene
Cyclopentadiene
Diacetone Alcohol
Decane
Diazomethanea; CH2N2
Dichlorobenzenea; C6H4Cl2
Dichloroethyl Ether
Dichloroethylenea; C2H2Cl2
Dichlorvos
Diesel Fuel
Diethylaminoethanol
Diethylamine
Diglycidyl Ether
Diisobutyl Ketone
Diisopropylamine
N,N-Dimethylacetamide
Dimethylaminea; C2H6N2O
Dimethylanilinea; C8H11N
Dimethylformamidea; C3H7NO
Dimethylhydrazinea; C2H8N2
Dimethyl Methyl Phosphonate
Dimethylphthalate
Dimethyl Sulfoxide
Dioxane a (Diethylene oxide); C4H8O2
Diphenyl
Epichlorohydrina (l-chloro-2,3-epoxy
propane); C3H5ClO
Ethane
Ethanola; CH4O
Ethanolamine
Ethoxyethyl Acetate
Ethyl Acetate
Ethyl Acrylatea; C5H8O2
Ethyl Amyl Ketone
Ethyl Benzene
Ethyl Bromidea (bromomethane); CH3Br
Ethyl Butyl Ketone
Ethylamine
Ethylene Dibromidea (1,2-
dibromoethane); C2H4Br2
Ethylenediamine
Ethyleneiminea (aziridine); C2H5N
Ethyl Ether
Ethyl Hexyl Acrylate
Ethyl Lactate
Ethyl Mercaptan
(aCompounds regulated by the US Environmental Protection Agency)
105
Continuation of Volatile Organic Compounds Detected By PID 10.6 eV Lamp
Ethyl Silicate
Ethyl Sulfide
Furfural
Furfuyl Alcohol
Gasoline
Glycidol
Heptane
Hexanea; C6H14
Hexanone
Hexyl Acetate
Hydrogen Sulfide
Hydroquinone
Iodine
Isoamyl Acetate
Isobutyl Acetate
Isobutyl Alcohol
Isopar
Isophoronea; C9H14O
Isopropyl Acetate
Isopropyl Alcohol
Isopropyl Ether
Isopropylamine
Isopropyl Glycidyl Ether
JP-4, -5, -8
Kerosene
Ketene
Limonene
Mesityl Oxide
Methyl Acetate
Methyl Acetylene
Methyl Acrylate
Methyl Amyl Ketone
Methyl Bromidea (bromomethane);
CH3Br
Methyl Cellosolve
Methyl Ethyl Ketonea (2-butanone);
C4H8O
Methyl Ether
Methyl Hydrazine
Methyl Iodidea (iodomethane); CH3I
Methyl Isocyanatea; C2H3NO
Methyl Mercaptan
Methyl Methacrylatea; C5H8O2
N-Methyl Pyrrolidone
Methyl Styrene
Methylamine
Methylcyclohexane
Methylcyclohexanone
(aCompounds regulated by the US Environmental Protection Agency)
106
Continuation of Volatile Organic Compounds Detected By PID 10.6 eV Lamp
Methylcyclohexanol
Mineral Spirits
Monomethylaniline
Morpholine
Naphtha
Naphthalene Nitroaniline
Nitrobenzenea; C6H5NO2
Nitrochlorobenzene
Nitromethane
Nitrotoluene
Nonane
Norpar Octane
Pentane
Pentanone
Perchloroethylene
PGMEA
Phenola; C6H6O
Phenyl Ether
Phenylene Diamine
Phenylhydrazine
Phosphine
Phthalic Anhydride
Pinene
Propyl Acetate
Propyl Alcohol
Propylene Dichloridea (1,2-
dichloropropane); C3H6Cl2
Propylene Imine
Propylene Oxidea; C3H6O
Pyridine
Quinone
Stibine
Stoddard Solvent
Styrenea; C8H8
Tetrachloroethylenea; C2Cl4
Tetrahydrofuran
Toluenea; C7H8
Toluene diisocyanate
Toluidine
Toner Fluid
Trichloroethylenea; C2HCl3
Triethylaminea; C6H15N
Triethyl Borate
Triethyl Phosphate
Turpentine
Vinyl Bromidea (bromoethene); C2H3Br
Vinyl Chloridea (chloroethene); C2H3Cl
(aCompounds regulated by the US Environmental Protection Agency)
98
Continuation of Volatile Organic Compounds Detected By PID 10.6 eV Lamp
Vinylidene Chloridea (1,1-dichloroethylene); C2H2Cl2
Vinyl Cyclohexene
Vinylpyrrolidinone
Vinyl Toluene
White Spirit
Xylenea (isomer & mixtures); C8H10
(aCompounds regulated by the US Environmental Protection Agency)
108
Appendix Eleven
Volatile Organic Compounds Not Detected by PID
(Source: RAE Systems Inc.)
Acetonitrile
Carbon Dioxide
Carbon Monoxide
Freons
Hydrogen
Hydrogen Bromide
Hydrogen Chloride
Hydrogen Cyanide
Hydrogen Fluoride
Hydrogen Peroxide
Methane
Nitric Acid
Nitrogen
Oxygen
Ozone
Sulfur Dioxide
Sulfuric Acid
Vikane (Sulfuryl Fluoride)
Water
109
Appendix Twelve
Aerial photographs of the school studied
Below can be found aerial photographs of the schools studied with a simple
outline of what is around the school.
Figure A10.01. Aerial photograph of the rural School 001.
Source: Google Earth 2007.
110
Figure A10.02. Aerial photograph of the urban School 002.
Source: Google Earth 2007.
111
Figure A10.03. Aerial photograph of the urban School 003.
Source: Google Earth 2007.
112
Figure A10.04. Aerial photograph of the rural School 004.
Source: Google Earth 2007.
113
Appendix Thirteen
Meteorological data of Caguas, Puerto Rico
These are the meteorological data for the days of the TVOC measurement study
from the Caguas station that is part of the MADIS Project in Puerto Rico. In the tables
below are the daily averages and weakly averages for the month of February 2008.
Table A14.01. Meteorological data for the days of indoor and outdoor sampling in
schools.
School Type of
Sampling
Temperature
(°C)
Humidity
(%)
Pressure
(mmHg)
Wind Velocity
(km/h)
001
Indoor 24.8 79 760.48 3.7
Outdoor 24.6 71 759.46 3.3
002 Indoor 24.5 74 759.97 4.6
Outdoor 23.6 78 759.97 4.4
003 Indoor 26.6 74 761.24 6.1
Outdoor 26.0 66 760.48 4.1
004 Indoor 23.6 79 760.98 4.0
Outdoor 23.1 80 762.25 2.9
114
Table A14.02. Weekly meteorological data for the month of February 2008.
Day Temperature
(°C)
Humidity
(%)
Pressure
(in.)
Wind Velocity
(km/h)
1 22.3 77 29.85 5.2
2 21.3 85 29.90 1.4
3 23.4 76 29.95 3.3
4 24.1 74 29.96 3.2
5 24.0 73 29.98 3.0
6 23.4 80 29.97 2.1
7 24.0 78 29.94 4.6
8 24.8 79 29.94 3.7
9 24.5 76 29.92 4.6
10 24.9 75 29.90 4.3
11 24.6 71 29.90 3.3
12 24.5 74 29.92 4.6
13 23.6 78 29.92 4.4
14 26.6 74 29.97 6.1
15 26.0 66 29.94 4.1
16 24.3 72 29.88 4.1
17 21.4 85 29.63 2.1
18 23.6 79 29.96 4.0
19 23.1 80 30.01 2.9
20 24.3 72 29.97 3.3
115
Continuation of TableA14.02. Weekly meteorological data for the month of February
2008.
Day
Temperature
(°C)
Humidity
(%)
Pressure
(in.)
Wind Velocity
(km/h)
21 24.8 72 29.97 3.3
22 24.6 72 29.97 4.1
23 24.2 76 29.99 3.6
24 24.2 74 29.96 3.4
25 25.4 73 29.91 3.8
26 24.8 75 29.91 4.1
27 22.3 82 29.90 2.2
Total Average
24.0
76
29.93
3.6
Table A14.03. Meteorological data averages for each week in February 2008.
Week
Temperature
(°C)
Humidity
(%)
Pressure
(in.)
Wind Velocity
(km/h)
1 21.8 81 29.87 3.3 2 24.0 76 29.95 3.5 3 24.9 73 29.92 4.4 4 23.7 76 29.93 3.3 5
24.1
76
29.92
3.4
116
Appendix Fourteen
Wind Resources of Puerto Rico
Figure A15.01. Wind Resources for Puerto Rico.
Source: AWS Truewind 2007.
117
Appendix Fifteen
Potential air quality problems in schools
Some problems that can cause decreased air quality are seen in the
photographs below. These photographs were taken in the schools studied and all of the
schools showed some degree of the same problems.
Sample one
Figure A11.01. Storage problem in classrooms.
118
Sample two
Figure A11.02. Electronic accumulation storage in classrooms.
119
Sample three
Figure A11.03. Mold growth outdoors problem in the school area.
120
Sample four
Figure A11.04. Sewers in front of the schools which can give off gases that affect air
quality.
121
Sample five
Figure A11.05. Construction of new school facilities during school hours.
122
Appendix Sixteen
Summarized climatologic day data sample
Table A12.01. Climatologic data results for school 001 from day of sample.
Parameters Indoor Outdoor
Temperature (°C) Mean 25 ± 1 26 ± 2
Max 27.1 28.9
Min 22.8 21.7
% Relative Humidity Mean 75 ± 5 64 ± 10
Max 85.3 80.8
Min 66.1 49.2
Wind Velocity Range
(m/s)
0.0 0.0-2.6
Observations Sunny day. There are cats
and dogs in the school
establishment.
Cloudy and sunny
day. There are
cats and dogs in
the school
establishment.
There was a
school bus picking
up students in the
afternoon.
123
Table A12.02. Climatologic data results for school 002 from day of sample.
Parameters Indoor Outdoor
Temperature (°C) Mean 22.8 ± 0.8 27 ± 1
Max 25.9 28.9
Min 22.4 24.0
%Relative Humidity Mean 61 ± 3 63 ± 7
Max 67.9 78.7
Min 56.9 52.7
Wind Velocity Range (m/s) 0.0 0.0-2.0
Observations Sunny day. The
classroom has air
conditioning and
collides with the
school parking and
with a cleaning area.
There is a lot of
storage. The air
conditioning was on
when the equipment
was started and the
air conditioning was
off when the
equipment was
acquired.
Cloudy day. Close
to the sample area
is a water hose and
a plastic basin
which they use to
clean. Also outside
the parameters of
the school are two
sewers with foul
odor.
124
Table A12.03. Climatologic data results for school 003 from day of sample.
Parameters Indoor Outdoor
Temperature (°C) Mean 27 ± 12 32 ± 4
Max 28.9 41.2
Min 24.9 22.4
% Relative Humidity Mean 62 ± 8 51 ± 12
Max 81.1 81.1
Min 51.8 31.2
Wind Velocity Range
(m/s)
0.0 0.4-0.8
Observations Cloudy day. The sample
classroom has marker
boards and chalk boards.
Also there are computers
which are not in use.
There was a little get
together party in the
afternoon.
Rainy day. The
sample was
taken close to
the school’s
parking lot
which collides
with a
mechanical
college. The
day of sampling
there were no
college classes.
125
Table A12.04. Climatologic data results for school 004 from day of sample.
Parameters Indoor Outdoor
Temperature (°C) Mean 27 ± 2 30 ± 3
Max 30.1 40.3
Min 23.6 27.3
% Relative Humidity Mean 61 ± 12 47 ± 7
Max 82.3 56.6
Min 42.9 29.3
Wind Velocity Range
(m/s)
0.0-0.5 0.3-1.1
Observations It was a rainy morning and
a cloudy afternoon. In the
morning there were
starting to clean the
classroom and when the
class started, the air
conditioning was turned
on.
It was a sunny
and cloudy day.
There doesn’t
seem to be any
traffic. We can
perceive a shift
of wind
direction during
the day.
126
Appendix Seventeen
Summarized TVOC measurement results data
Table A13.01. Summarized indoor and outdoor TVOC results measurements for the
schools studied (n=5560).
School Indoor (mg/m3) Outdoor (mg/m3) Mean
Ratio (I/O) Mean Max Min Mean Max Min
001 0 ± 0 0.0 0.0 0 ± 0 0.0 0.0 0.0
002 0.0 ± 0.6 47.20 0.0 0 ± 5 76.50 0.0 0
003 0.0 ± 0.3 22.07 0.0 0 ± 2 126.88 0.0 0
004 18 ± 31 468.91 0.0 5 ± 16 95.16 0.0 3.6
Table A13.02. Summarized indoor and outdoor TVOC comparison measurements for
urban schools studied.
School Indoor (mg/m3) Outdoor (mg/m3) Mean
Ratio (I/O) Mean Max Min Mean Max Min
001 0 ± 0 0.0 0.0 0 ± 0 0.0 0.0 0.0
004 18 ± 31 468.91 0.0 5 ± 16 95.16 0.0 3.6
127
Table A13.03. Summarized indoor and outdoor TVOC comparison measurements for
rural schools studied.
School Indoor (mg/m3) Outdoor (mg/m3) Mean
Ratio (I/O) Mean Max Min Mean Max Min
002 0.0 ± 0.6 47.20 0.0 0 ± 5 76.50 0.0 0
003 0.0 ± 0.3 22.07 0.0 0 ± 2 126.88 0.0 0
128
Appendix Eighteen
Glossary terms
Ambient air – the air immediately around us.
Anthropogenic emissions - emissions of particles or substances resulting from human
activities, such as industry and agriculture.
Asthma – a distressing disease characterized by shortness of breath, wheezing and
bronchial muscle spasm.
CAA - Clean Air Act. Federal law mandating and enforcing toxic emissions standards for
stationary and mobile sources.
Cancer – is an invasive, out of control cell growth that results in malignant tumors.
Carcinogen – substance that causes cancer.
CDC - Center of Disease Control
CFCs - Chlorofluorocarbons, compounds containing chlorine and fluorine bonds that
have been used as refrigerants. These compounds have been shown to deplete
stratospheric ozone and can also act as greenhouse gases.
Chronic effects – long-lasting results of exposure to a toxin; can be a single, acute
exposure or a continuous low level exposure.
Chronic Exposure - exposure to a substance over a long period of time.
Climate - the long term average condition of the weather in a given area.
Climate change: the slow variations of climatic characteristics over time at a given
place. Usually refers to the change of climate which is attributed directly or
indirectly to human activity that alters the composition of the global atmosphere
and which is, in addition to natural climate variability, observed over comparable
periods.
129
Climate system: the totality of the atmosphere, hydrosphere, biosphere, and geosphere
and their interactions that characterize the average and extreme conditions of the
atmosphere over a long period of time at any one place or region of the earth's
surface.
Compound – a molecule made up of two or more kinds of atoms held together by
chemical bonds.
Contaminant: any biological, chemical, physical or radiological substance that has an
negative effect on air, soil or water.
Disease – a deleterious change in the body’s condition in response to destabilizing
factors.
Emissions - the release of gaseous substances into the atmosphere.
Emission standards – regulations for restricting the amounts of air pollutants that ca be
released from specific point sources.
Environment – the circumstances or conditions that surround an organism or group of
organisms.
EPA - Environmental Protection Agency U.S.. Primary federal agency responsible for
enforcement of federal laws protecting the environment.
Global warming - the warming of the earth's surface, driven by either natural or
anthropogenic forces.
Greenhouse gases - gases that absorb atmospheric and solar infrared radiation and
reflect it back to earth to increase global warming, causing climate change.
Ground-level ozone (tropospheric ozone): Ozone (O3) that occurs near the surface of
the Earth. In pollution it causes concern because of its toxic effects.
Hazardous – describes chemicals that are dangerous including flammables, explosives,
irritants, sensitizers, acids and caustics; may be relative harmless in diluted
concentrations.
130
Hazardous Air Pollutant - a pollutant to which no ambient quality standard is applicable
and that may cause or contribute to an increase in mortality or in serious illness.
Half-life - also referred to as decay constant; the term is used to quantify a first-order
exponential decay process.
Health – a state of physical and emotional well-being the absence of diseases or
ailment.
Inhalation - the breathing of airborne contaminants in the form of vapors, gases, mists,
or particulates may produce harmful effects.
Kyoto Protocol – is an international agreement to reduce greenhouse gas emission.
MADIS - Meteorological Assimilation Data Ingest System is dedicated toward making
value-added data available from the National Oceanic and Atmospheric
Administration's.
Monitoring - the process of measuring certain environmental parameters on a real-time
basis for spatial and time variations. For example, air monitoring may be
conducted with direct-reading instruments to indicate relative changes in air
contaminant concentrations at various times.
Morbidity – illness or disease.
Mortality – death rate in a population; the probability of dying.
Mutagens – agent such as chemicals or radiation that damages or alters genetic
materials in cells.
Mutation – a change either spontaneous or by external factors, in the genetic materials
for a cell.
NAAQS – National Ambient Air Quality Standard; federal standards specifying the
maximum allowable levels for regulated pollutants in ambient air.
Neurotoxins – toxic substances that specifically poison nerve cells.
NIOSH - National Institute of Occupational Safety and Health
131
Nitrogen oxides – is a highly reactive gas from when nitrogen-containing compounds
are oxidized.
NOAA - National Oceanic and Atmospheric Administration
OSHA - Occupational Safety and Health. Act of 1970, oversees and regulates work
place health and safety.
Ozone: a gas composed of three atoms of oxygen (03). Ozone partially filters certain
wavelengths of ultraviolet light from the Earth. Ozone is a desirable gas in the
stratosphere, but in high concentrations at ground level, it is toxic to living
organisms.
Ozone layer (stratospheric ozone): ozone that is formed in the stratosphere from the
conversion of oxygen molecules by solar radiation. Ozone absorbs much
ultraviolet radiation and prevents it from reaching the Earth.
Photochemical oxidants – products of secondary atmosphere reactions.
PID – Photo Ionization Detector
Pollutant - legally, any dredged spoil, solid waste, incinerator residue, filter backwash,
sewage, garbage sewage sludge, munitions, chemical wastes, biological
materials, radioactive materials (except those regulated under the Atomic Energy
Act, heat, wrecked or discharged into water. From a practical perspective, any
substance or mixture which after release into the environment and upon
exposure to any organism will or may reasonable be anticipated to cause
adverse effects in such organisms or their offspring.
Pollution – activities that alter the environment in undesirable ways.
PR – Puerto Rico
Relative humidity – at any given temperature, a comparison of the actual water content
of the air with the amount of water that could be held at saturation.
Smog – term used to describe photochemical pollution products.
132
Source - any process, activity or mechanism which releases contaminants in the
atmosphere.
Temperature – a measurement of the speed of motion of a typical atom or molecule in a
substance.
Toxic - harmful to living organisms.
TVL – Threshold Value Limit
TVOC – Total Volatile Organic Compounds.
Vapor - an air dispersion of molecules of a substance that is liquid or solid in its normal
physical state, at standard temperature and pressure.
VOC – Volatile Organic Compounds; organic compounds that evaporate readily and
exists as gasses in the air.
Weather – description of the physical conditions at the atmosphere.