Air Pollution: Origin, Fate and Effects of Pollutants

Air PollutionIndoorRegionalGlobalStratosphericSourcesEffectsTreatment

Air Pollution and Public OpinionProblems in many urban areas in late 1800s and early 1900 due to coal use1000s of deaths attributed to air pollution episodes in London large number of pollution sourcesrestricted air volumefailure to recognize problemwater droplets of certain sizePhotochemical smog: CO+NOx+HC+light

Air Pollution StandardsNational Ambient Air Quality Standards (NAAQS) promulated under the 1970 Clean Air Act (CAA).Criteria pollutantsPrimary standards designed to protect human health with an adequate margin of safety.Secondary standards are intended to prevent environmental and property damage.

Air Pollution Standards

Units of Measurereview pages 73-78g/m3 mass:volumeparts per million (ppm) volume:volume

where C = concentration in g/m3m particle size

Air Pollution StandardsHazardous Air Pollutants (HAPs) National Emission Standards for Hazardous Air Pollutants (NESHAPs) 1970 CAARisk-based approach used asbestos, arsenic, benzene, beryllium, mercury, vinyl chloride and radionuclidesMaximum Achievable Control Technology (MACT) standards 1990 CAA189 chemicals from 174 categories of industrial sources being established

Control of Criteria Air PollutantsA geographic area that meets or does better than the primary standard is called an attainment area; areas that don't meet the primary standard are called nonattainment areas.Although EPA has been regulating criteria air pollutants since the 1970 CAA was passed, many urban areas are classified as nonattainment for at least one criteria air pollutant. It has been estimated that about 90 million Americans live in nonattainment areas.

Control of Criteria Air PollutantsStates must have State Implementation Plans formulated and filed with US EPA. These plans (a collection of regulations) describe how attainment will be achieved (within a particular time period). (Michigans: http://www.epa.gov/ARD-R5/sips/)States must involve the public in the approval process before a SIP is finalizedIf an SIP is not acceptable, the USEPA can assume responsibility for enforcing the CAA in that State.

Carbon MonoxideMost abundant air pollutantProduced by incomplete combustioninsufficient O2low temperatureshort residence timepoor mixingMajor source (~ 77%) is motor vehicle exhaust

http://www.epa.gov/oar/aqtrnd97/brochure/co.html

Carbon MonoxideColorless and odorless When inhaled, binds to hemoglobin in blood to form carboxyhemoglobin, reducing the oxygen carrying capacitybrain function reduced, heart rate increased at lower levelsasphyxiation occurs at higher levels

Carbon Monoxide

Carbon MonoxideTypical Levelsbusy roadways: 5 50 ppmcongested highways: up to 100 ppmbars: up to 30 ppmVehicle emission rates:

Carbon Monoxide: Trends in LevelsAir quality still an issue:Increasing vehicle population Increasing travel per vehicle1980: average 9,500 miles/year1995: average 11,800 miles/yrVehicle miles of travel: Increase of 3.1%/ yrDepartures from Federal standardsGreater use of light trucks (including SUVs)

Oxides of Nitrogen (NOx)Primarily NO and NO2NO3, N2O, N2O3, N2O4, N2O5 are also known to occurThermal NOx created by oxidation of atmospheric N2 when T > 1000 KFuel NOx from oxidation of N in fuel

http://www.epa.gov/oar/aqtrnd97/brochure/no2.html

Oxides of Nitrogen (NOx)NO has few health effects, but is oxidized to NO2NO2 irritates lungs and promotes respiratory infectionsNO2 reacts with hydrocarbons in presence of sunlight to produce smogNO2 reacts with hydroxyl radicals to produce nitric acid acid precipitation

Photochemical Smoghydrocarbons + NOx + sunlight photochemical smog (oxidants)primary oxidants produced:ozone (O3)formaldehydeperoxyacetyl nitrate (PAN)

Photochemical Smog

Photochemical Smog

Ozone: Health EffectsIncreased incidents of respiratory distress.Repeated exposures to ozone:Increased susceptibility to respiratory infectionLung inflammationAggravation of pre-existing respiratory diseases such as asthma. Decreases in lung function and increased respiratory symptoms such as chest pain and cough.

Ozone: Environmental EffectsOzone also affects vegetation and ecosystemsreductions in agricultural and commercial forest yields ($0.5 billion/yr in US alone)reduced growth and survivability of tree seedlingsincreased plant susceptibility to disease, pests, and other environmental stresses (e.g., harsh weather). http://www.ncl.ac.uk/airweb/ozone/greece.jpg

Ozone Revised StandardsIn 1997, the 1-hour ozone standard of 0.12 parts per million (ppm) was replaced with a new 8-hour 0.08 ppm standard. Areas that do not meet the new 8-hour standard will not be designated "nonattainment" until this year.

Sulfur Oxides (SOx)SO2, SO3, SO42 formed during combustion of fuel containing sulfurH2S released is converted to SO210 Tg/yr natural sources75 Tg/yr anthropogenic sources

http://www.epa.gov/oar/aqtrnd97/brochure/so2.html

Sulfur Dioxide: Health EffectsHigh concentrations of SO2 can result in temporary breathing impairment. Longer-term exposures to high concentrations of SO2, in conjunction with high levels of PM, include respiratory illness, alterations in the lungs' defenses, and aggravation of existing cardiovascular diseaseShort-term exposures of asthmatic individuals to elevated SO2 levels may result in reduced lung function.

Sulfur Dioxide: Environmental EffectsAcid Rain Decreased Visibilityhttp://www.epa.gov/oar/vis/rockymtn.html

Particulate MatterSolid or liquid particles with sizes from 0.005 100 mGeneral term is aerosols Dust originates from grinding or crushingFumes are solid particles formed when vapors condenseSmoke describes particles released in combustion processesSmog used to describe air pollution particles

Health Efffects of Particluate MatterImpact depends on particle size, shape and compositionLarge particles trapped in noseParticles >10 m removed in tracheobronchial systemParticles

Particulate MatterPM-2.5 (1997)< 2.5 m diameter Similar sources, but tend to be more toxicologically active particlesEPA estimates new standard will save 15,000 lives/yrPM-10 (1987)< 10 m diameterfuel combustion (45%)industrial processing (33%)Transportation (22%)Original standards did not account for size larger particles that were not problematic dominated

Particulate Matter: Revised StandardsTwo new PM-2.5 standards 15 micrograms per cubic meter (g/m3) and 65 g/m3, respectively, for the annual and 24-hour standards. In addition, the form of the 24-hour standard for PM-10 was changed. Beginning in 2002, EPA will designate areas as nonattainment that do not meet the new PM-2.5 standards.

Particulate Matter: Health EffectsInhalable PM includes both fine and coarse particles. Coarse particles aggravation of respiratory conditions, such as asthma. Fine particles increased hospital admissions and emergency room visits for heart and lung diseaseincreased respiratory symptoms and diseasedecreased lung functionpremature death

Particulate Matter: Environmental EffectsDecreased visibilityDamage to paints and building materialshttp://www.epa.gov/oar/vis/bryce.html

LeadSources:gasoline (historical)metals processing Highest air Pb concentrations in the vicinity of nonferrous and ferrous smelters, and battery manufacturers.

Lead: Health EffectsAccumulates in the blood, bones, and soft tissues. Adversely affects the kidneys, liver, nervous system, and other organs.Excessive exposure to Pb may cause neurological impairments, such as seizures, mental retardation, and behavioral disorders.May be a factor in high blood pressure and subsequent heart disease.

Nature and Sources of the Pollutant: Carbon monoxide (CO) is a colorless, odorless and at high levels, a poisonous gas, formed when carbon in fuel is not burned completely. It is a component of motor vehicle exhaust, which contributes about 60 percent of all CO emissions nationwide. High concentrations of CO generally occur in areas with heavy traffic congestion. In cities, as much as 95 percent of all CO emissions may come from automobile exhaust. Other sources of CO emissions include industrial processes, non-transportation fuel combustion, and natural sources such as wildfires. Peak CO concentrations typically occur during the colder months of the year when CO automotive emissions are greater and nighttime inversion conditions (where air pollutants are trapped near the ground beneath a layer of warm air) are more frequent.Carbon monoxide enters the blood-stream through the lungs and reduces oxygen delivery to the body's organs and tissues. At much higher levels of exposure, CO can be poisonous and even healthy individuals may be affected. Visual impairment, reduced work capacity, reduced manual dexterity, poor learning ability, and difficulty in performing complex tasks are all associated with exposure to elevated CO levels.

. Use the emission standards given above:

% HC reduction = (6.59-0.155)/ 6.59 x 100% = 97.6%% CO reduction = (52.2-2.11)/52.2 x 100% = 96.0%VMT: Miles travelled per vehicle x total number of vehicles

Many cars emit more pollution than that determined in federal test procedures (improper maintenance, tampering with control devices, etc.)

Greater use of light trucks - federal emission standards prior to 1994 allowed 2-3 times more emissions for light trucks than for passenger cars - still not euqal.Nature and Sources of the Pollutant: Nitrogen dioxide (NO2) is a reddish brown, highly reactive gas that is formed in the ambient air through the oxidation of nitric oxide (NO). Nitrogen oxides (NOx), the term used to describe the sum of NO, NO2 and other oxides of nitrogen, play a major role in the formation of ozone. The major sources of man-made NOx emissions are high-temperature combustion processes, such as those occurring in automobiles and power plants. Home heaters and gas stoves also produce substantial amounts of NO2 in indoor settings.

Health and Environmental Effects: Short-term (1-3 hours) and prolonged (6-8 hours) exposures to ambient ozone have been linked to a number of health effects of concern. For example, increased hospital admissions and emergency room visits for respiratory causes have been associated with ambient ozone exposures. Repeated exposures to ozone can make people more susceptible to respiratory infection, result in lung inflammation, and aggravate pre-existing respiratory diseases such as asthma. Other health effects attributed to ozone exposures include significant decreases in lung function and increased respiratory symptoms such as chest pain and cough. These effects generally occur while individuals are engaged in moderate or heavy exertion. Children active outdoors during the summer when ozone levels are at their highest are most at risk of experiencing such effects. Other at-risk groups include adults who are active outdoors (e.g., outdoor workers), and individuals with pre-existing respiratory disease such as asthma and chronic obstructive lung disease. In addition, longer-term exposures to moderate levels of ozone present the possibility of irreversible changes in the lungs which could lead to premature aging of the lungs and/or chronic respiratory illnesses.

Ozone also affects vegetation and ecosystems, leading to reductions in agricultural and commercial forest yields, reduced growth and survivability of tree seedlings, and increased plant susceptibility to disease, pests, and other environmental stresses (e.g., harsh weather). In long-lived species, these effects may become evident only after several years or even decades, thus having the potential for long-term effects on forest ecosystems. Ground-level ozone damage to the foliage of trees and other plants also can decrease the aesthetic value of ornamental species as well as the natural beauty of our national parks and recreation areasHealth and Environmental Effects: Short-term (1-3 hours) and prolonged (6-8 hours) exposures to ambient ozone have been linked to a number of health effects of concern. For example, increased hospital admissions and emergency room visits for respiratory causes have been associated with ambient ozone exposures. Repeated exposures to ozone can make people more susceptible to respiratory infection, result in lung inflammation, and aggravate pre-existing respiratory diseases such as asthma. Other health effects attributed to ozone exposures include significant decreases in lung function and increased respiratory symptoms such as chest pain and cough. These effects generally occur while individuals are engaged in moderate or heavy exertion. Children active outdoors during the summer when ozone levels are at their highest are most at risk of experiencing such effects. Other at-risk groups include adults who are active outdoors (e.g., outdoor workers), and individuals with pre-existing respiratory disease such as asthma and chronic obstructive lung disease. In addition, longer-term exposures to moderate levels of ozone present the possibility of irreversible changes in the lungs which could lead to premature aging of the lungs and/or chronic respiratory illnesses.

Ozone also affects vegetation and ecosystems, leading to reductions in agricultural and commercial forest yields, reduced growth and survivability of tree seedlings, and increased plant susceptibility to disease, pests, and other environmental stresses (e.g., harsh weather). In long-lived species, these effects may become evident only after several years or even decades, thus having the potential for long-term effects on forest ecosystems. Ground-level ozone damage to the foliage of trees and other plants also can decrease the aesthetic value of ornamental species as well as the natural beauty of our national parks and recreation areasRevised Ozone Standards: In 1997, EPA revised the national ambient air quality standards for ozone by replacing the 1-hour ozone 0.12 parts per million (ppm) standard with a new 8-hour 0.08 ppm standard. The revision to the O3 standard was set such that the 1-hour standard will no longer apply once an area has air quality data meeting the 1-hour standard. Although areas that do not meet the new 8-hour standard will not be designated "nonattainment" until the year 2000, EPA is beginning to track trends in 8-hour levels of ozone.Nature and Sources of the Pollutant: Sulfur dioxide belongs to the family of sulfur oxide gases. These gases are formed when fuel containing sulfur (mainly, coal and oil) is burned and during metal smelting and other industrial processes. Most SO2 monitoring stations are located in urban areas. The highest monitored concentrations of SO2 are recorded in the vicinity of large industrial facilities.Health and Environmental Effects: High concentrations of SO2 can result in temporary breathing impairment for asthmatic children and adults who are active outdoors. Short-term exposures of asthmatic individuals to elevated SO2 levels while at moderate exertion may result in reduced lung function that may be accompanied by such symptoms as wheezing, chest tightness, or shortness of breath. Other effects that have been associated with longer-term exposures to high concentrations of SO2, in conjunction with high levels of PM, include respiratory illness, alterations in the lungs' defenses, and aggravation of existing cardiovascular disease. The subgroups of the population that may be affected under these conditions include individuals with cardiovascular disease or chronic lung disease, as well as children and the elderly.Together, SO2 and NOx are the major precursors to acidic deposition (acid rain), which is associated with the acidification of soils, lakes, and streams, accelerated corrosion of buildings and monuments, and reduced visibility. Sulfur dioxide also is a major precursor to PM-2.5, which is a significant health concern as well as a main pollutant that impairs visibility.

Nature and Sources of the Pollutant: Particulate matter (PM) is the general term used for a mixture of solid particles and liquid droplets found in the air. Some particles are large or dark enough to be seen as soot or smoke. Others are so small they can be detected only with an electron microscope. These particles, which come in a wide range of sizes ("fine particles are less than 2.5 micrometers in diameter and coarser-size particles are larger than 2.5 micrometers), originate from many different stationary and mobile sources as well as from natural sources. Fine particles (PM-2.5) result from fuel combustion from motor vehicles, power generation, and industrial facilities, as well as from residential fireplaces and wood stoves. Coarse particles (PM-10) are generally emitted from sources, such as vehicles traveling on unpaved roads, materials handling, and crushing and grinding operations, as well as windblown dust. Some particles are emitted directly from their sources, such as smokestacks and cars. In other cases, gases such as sulfur oxide and SO2, NOx, and VOC interact with other compounds in the air to form fine particles. Their chemical and physical compositions vary depending on location, time of year, and weather.Revised Particulate Matter Standards: In 1997, EPA added two new PM-2.5 standards, set at 15 micrograms per cubic meter (g/m3) and 65 g/m3, respectively, for the annual and 24-hour standards. In addition, the form of the 24-hour standard for PM-10 was changed. EPA is beginning to collect data on PM-2.5 concentrations. Beginning in 2002, based on 3 years of monitor data, EPA will designate areas as nonattainment that do not meet the new PM-2.5 standards.Health and Environmental Effects: Inhalable PM includes both fine and coarse particles. These particles can accumulate in the respiratory system and are associated with numerous health effects. Exposure to coarse particles is primarily associated with the aggravation of respiratory conditions, such as asthma. Fine particles are most closely associated with such health effects as increased hospital admissions and emergency room visits for heart and lung disease, increased respiratory symptoms and disease, decreased lung function, and even premature death. Sensitive groups that appear to be at greatest risk to such effects include the elderly, individuals with cardiopulmonary disease, such as asthma, and children. In addition to health problems, PM is the major cause of reduced visibility in many parts of the United States. Airborne particles also can cause damage to paints and building materials.PM is the major cause of reduced visibility in many parts of the United States. Airborne particles also can cause damage to paints and building materials.

Nature and Sources of the Pollutant: In the past, automotive sources were the major contributor of Pb emissions to the atmosphere. As a result of EPA's regulatory efforts to reduce the content of Pb in gasoline, the contribution from the transportation sector has declined over the past decade. Today, metals processing is the major source of Pb emissions to the atmosphere. The highest air concentrations of Pb are found in the vicinity of nonferrous and ferrous smelters, and battery manufacturers.Health and Environmental Effects: Exposure to Pb occurs mainly through inhalation of air and ingestion of Pb in food, water, soil, or dust. It accumulates in the blood, bones, and soft tissues. Lead can adversely affect the kidneys, liver, nervous system, and other organs. Excessive exposure to Pb may cause neurological impairments, such as seizures, mental retardation, and behavioral disorders. Even at low doses, Pb exposure is associated with damage to the nervous systems of fetuses and young children, resulting in learning deficits and lowered IQ. Recent studies also show that Pb may be a factor in high blood pressure and subsequent heart disease. Lead can also be deposited on the leaves of plants, presenting a hazard to grazing animals.