environmental education indoor air pollution. contents introduction sources and impacts of common...

Environmental Education

Indoor Air Pollution

ContentsIntroductionSources and impacts of common indoor air pollutantsSick Building Syndrome (SBS) Legionnaires’ diseaseControl measures

Introduction“Acceptable Indoor air quality”:

Air in an occupied space towards which a substantial majority of occupants express no dissatisfaction, and in which there are not likely to be known contaminants at concentrations leading to exposures that pose a significant health risk

Sources of information: web site of ASHARE (http://www.ashrae.org/ )

Common indoor air pollutants [1]

Biological contaminants Carbon dioxide Carbon monoxide Nitrogen oxides Environmental tobacco smoke Formaldehyde Volatile organic compounds (VOCs) Ozone Radon


Biological contaminants Bacteria, fungi and virusesBreed in humid environmentSpread through ventilation systemsSources:

Naturally exist in air, humid and poor ventilated area

Effects:Vary with types

e.g. Sick Building Syndrome, Legionnaires’ disease, Colds and Influenza


Carbon dioxide No color, smell and tasteAccumulate in poorly ventilated areasNon-toxic but makes ones uncomfortable in high concentrations Sources:

Exhalation by living organisms during respirationCombustion

Effects:Feel sleepy and sensitive individuals may feel dizzy


Carbon monoxide No color, smell and tasteInhibits oxygen transport in bloodIrreversibly binds to hemoglobinVery toxicSources:

Incomplete combustionEffects:

Low concentration:Flu-like symptoms, such as nausea, fatigue, rapid breathing, chest tightness and impaired judgement, cardiovascular diseases

High concentration:death

Carbon dioxide and carbon monoxide are released during combustion. (Sources: http://hkcg.com)


Nitrogen oxides e.g. NO and NO2

Gas generated from combustions

Sources:Burning of cigarette

Vehicles exhaust fumes

Effects:Irritate eye and respiratory tract


Environmental tobacco smoke (ETS)Mixture:

smoke from the burning cigarette or cigarexhaled smoke from smokers

At least 4,500 compounds found in tobacco smoke

60 of the 4,500 compounds are known as carcinogensSome components such as hydrogen cyanide, nicotine and nitrogen oxides are toxic and irritative

EffectsEspecially harmful to childrenIncrease the incidence of respiratory tract infections, lung cancers and heartEnvironmental tobacco smoke includes the smoke from burning

cigarette and exhaled smoke from smoker. (Sources: http://www.corbis.com)


Volatile organic compounds (VOCs) A range of organic compoundsExamples: benzene, chloroform and xyleneEvaporate at room temperatureSome are carcinogens, e.g. benzene and formaldehyde Sources:

Solvents, cleaning agents, wood, paints, plastic, dyes, office machines (fax machines,computers, printers, etc), insecticides, and etc.

Effects:eye, nose, throat and respiratory tract irritation, headaches, poor concentration, dizziness and tirednessdamages of central nervous system, liver and kidney


Cleaning agents are also a source of indoor VOCs. (Sources: http://www.wellcome.hk.com)

Some home appliance such as personal computer can release VOCs too. (Sources: http://www.fortress.com.hk)

• Volatile organic compounds (VOCs) (con’t)


Formaldehyde One of Volatile organic compounds (VOC)Chemical smell in high concentrationSources:

Paints, plastics, pressed-wood products, plywood and urea-formaldehyde foam insulation, etc.

Effects:Irritate and sensitize eye, nose and respiratory tractCarcinogen

Oil-based paints are a source of indoor VOCs. (Sources: http://www.corbis.com)


Ozone Odorless and colorlessHighly reactiveSources:

photocopier, laser printers and ionisers

Effects: Damage lung seriouslyIrritate eye and respiratory tract

Photocopiers also release ozone. (Sources: http://www.fortress.com)


Radon No color, smell and tasteradioactive. Sources:

Release from granite in the concrete building.

Effects:Prolonged intake:

increase the incidence of lung cancerThe mixture of radon and tobacco smoke is much more harmful to humanSmokers have high probability of having lung cancers than non-smokers under the same level of radon.

Sick Building Syndrome (SBS)

A range of symptomsincluding eyes, nose and throat irritation, flu-like symptoms, chest tightness, headaches, lethargy, poor concentration and itchy skin with rash

Not life-threateningCommonly occur in air-conditioned buildingsThe syndrome causes

poor work performance, higher rate of absenteeism and sick leaves

Poor indoor air quality is believed to be a major contributing factor

Legionnaires’ diseaseCaused by bacteria, Legionnella pneumophila

Symptoms:Pneumonia, high-fever, chills, headache and muscle pain

Control measures

Eliminate the sources of pollutant Increase ventilation Keep the ventilation system clean

Upgrade, clean and sterilize the air conditioner is one way to keep the indoor air in good quality. (Sources: http://www.fortress.com.hk)

Covering the wall with wallpaper can eliminate the release of radon from concrete. (Sources: http://www.corbis.com)

DiscussionHave you ever felt uncomfortable in an indoor environment with flu-like symptoms, but they all disappear once you move out to outdoor environment? Where? How do you explain?What kind of indoor air pollutants could be found in the classroom?How do the problems associated with indoor air quality affect the social and economic development in Hong Kong?How do the government and you help to improve the indoor air quality?

Relevant WebsitesHong Kong Council on Smoking and Health (http://www.info.gov.hk/hkcosh/)Indoor Air Quality Association (http://www.iaqa.org)Indoor Air Quality Information Centre (http://www.iaq.gov.hk/)World Health Organisation (WHO) (http://www.who.int/home-page/)Environmental Protection Department (http://www.info.gov.hk/epd/index.htm)

environmental education indoor air pollution. contents introduction sources and impacts of common...

Documents