Grades 6-8
Section 1: Introduction to Air Quality
Particulates (PM)
Carbon Monoxide (CO)
Nitrogen Oxides (NOx)
Sulfur Dioxide (SO2)
lead (Pb)
Ozone (O3)
Air is never absolutely pollution-free. Small suspended solids and liquids from sources such as dust, forest fires, volcanic activity, and salt from the oceans are constantly moving around in the atmosphere. In fact, these minute particles are important for cloud formation. As moist air cools, water droplets begin collecting on particulate matter, building clouds. The more particles and water vapor, the more clouds that are formed. Precipitation cleanses the air of particulates, which is why the air is cleaner and clearer after a rainstorm.
However, human activities add significant amounts of pollutants to the atmosphere, often exceeding the ability of natural processes to eliminate them. Air pollution comes from many different sources. These include stationary sources such as factories, power plants, and smelters; smaller sources such as dry cleaners and degreasing operations; mobile sources such as cars, buses, planes, trucks, and trains; and natural sources such as windblown dust and wildfires. More people in cities and surrounding counties means more cars, trucks, industrial and commercial operations, and generally means more pollution. In addition, some pollutants are even found in nature.
Even before Tulsa’s first oil boom, in 1901, Tulsans experienced air pollution. Coal mining, farming, and day-to-day activities contributed. The Arkansas River corridor provided a growing Tulsa, rich in oil heritage, with industrial benefit. As the area grew economically, so did air pollution issues.
The average person breathes 3,400 gallons of air each day. Many air pollutants, such as those that form urban smog and toxic compounds, remain in the environment for long periods of time and are carried by the winds hundreds of miles from their origin. Millions of people live in areas where urban smog, very small particles, and toxic pollutants pose serious health concerns.
Exposure to air pollution is associated with numerous effects on human health, including respiratory problems, hospitalization for heart or lung diseases, and even premature death. Children are at greater risk, because they are generally more active outdoors, and their lungs are still developing. The elderly and people with heart or lung diseases are also more sensitive to some types of air pollution. Different people can be sensitive to different air pollutants. For example, ozone might make you cough. Particulate matter may not bother you, but it may make your grandmother cough and need to rest. One especially sensitive group to pollutants in the air is people with asthma.
Air pollution can also significantly affect ecosystems. For example, ground-level ozone has been estimated to cause over $500 million in annual reductions of agricultural and commercial forest yields.
Air pollution is measured from over 3,000 locations (over 5,200 monitors) across the nation operated primarily by state, local, and tribal agencies. Additionally, emissions from sources are monitored. Air pollution can be divided into two broad categories. Primary pollutants are emitted directly into the atmosphere. Secondary pollutants are formed by chemical reactions from atmosphere emissions that may not be hazardous until they come into contact with each other.
In response to the Clean Air Act requirements (discussed in detail in Section II), the Environmental Protection Agency (EPA) has identified six criteria pollutants: particulates, carbon monoxide, nitrogen dioxide, sulfur dioxide, lead, and ozone. EPA has determined and set National Ambient Air Quality standards (NAAQS) for these pollutants. Back to Top
Particulates
Particulate matter, or PM,
is the term for particles found in the
air, including dust, dirt, soot, smoke, and liquid droplets. They can
be primary or secondary pollutants and from natural or man-made
sources.
Particles can be suspended in the air for long periods of time. Some
particles are large or dark enough to be seen as soot or smoke. Others
are so small that individually they can only be dete
cted with an
electron microscope.
Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood.
Other particles may be formed in the air from the chemical change of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.
These solid and liquid particles come in a wide range of sizes. Particles less than 10 micrometers in diameter (PM10) tend to pose the greatest health concern because they can be inhaled into and accumulate in the respiratory system. Particles less than 2.5 micrometers in diameter (PM2.5) are referred to as “fine” particles. Sources of fine particles include all types of combustion (motor vehicles, power plants, wood burning, etc.) and some industrial processes. Particles with diameters between 2.5 and 10 micrometers are referred to as “coarse.” Sources of coarse particles include crushing or grinding operations, and dust from paved or unpaved roads.
Humans constantly breathe suspended particles. For the most part, cilia lining the airways remove most of them, but the process can take days. When particulate concentration in the atmosphere is especially heavy, natural functions of the respiratory system can become compromised, especially in people who suffer from asthma or other respiratory illnesses. Heavy PM concentrations are linked to increased emergency room visits and work and school absences.
PM is the major cause of reduced visibility (haze) in parts of the United States, including many of our national parks.
Wind can carry particulate matter miles away from the source until it finally settles on cropland, forests, or in bodies of water where it can change pH and mineral content, depleting nutrients and disrupting ecosystems. Additionally, particulate matter in the form of soot stains and damages stone and other building material.
The Oklahoma Department of Environmental Quality (ODEQ) is the responsible division for the implementation of state and federal air quality requirements for the Tulsa area. ODEQ monitors particulate matter, and the area is in compliance of the PM NAAQS. Real-time PM2.5 and PM10 monitoring data of the Tulsa area can be found on line at: http://www.deq.state.ok.us/AQDnew/monitoring/cpdata.htm
What are the health effects of PM and who is most at risk?
Both fine and coarse particles can accumulate in the respiratory system and are associated with numerous health effects. Coarse particles can aggravate respiratory conditions such as asthma. Exposure to fine particles is associated with several serious health effects, including premature death. Adverse health effects have been associated with exposures to PM over both short periods (such as a day) and longer periods (a year or more).
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· When exposed to PM, people with existing heart or lung diseases—such as asthma, chronic obstructive pulmonary disease, congestive heart disease, or ischemic heart disease—are at increased risk of premature death or admission to hospitals or emergency rooms.
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· The elderly also are sensitive to PM exposure. They are at increased risk of admission to hospitals or emergency rooms and premature death from heart or lung diseases.
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· When exposed to PM, children and people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would, and they may experience symptoms such as coughing and shortness of breath.
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· PM can increase susceptibility to respiratory infections and can aggravate existing respiratory diseases, such as asthma and chronic bronchitis, causing more use of medication and more doctor visits.
Carbon monoxide, or CO, is a colorless, odorless gas, CO is a primary pollutant formed from incomplete fuel combustion. Carbon monoxide from natural sources, such as volcanic eruptions or forest fires, is effectively removed by microbial action. Human activities in cities, however, are of particular concern, since CO input often exceeds removal rates, leading to potentially unsafe conditions. Nationwide about 56% of CO is from cars and truck exhaust. In cities, motor vehicle exhaust can contribute much more. The most currently available Tulsa area CO emissions inventory indicates that up to 97% of all CO emissions come from vehicle (on and off-road) exhaust. Non-road CO emissions comes from non-road sources such as construction equipment, airplanes, and boats. Other sources of CO include industrial activities, residential sources such as fireplaces or outdoor grills, and forest and grass fires.
Carbon monoxide concentrations typically are highest during cold weather 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.. The ODEQ monitors carbon monoxide levels in the Tulsa area. The Tulsa area is in compliance of the NAAQS for CO. Real-time CO monitoring data of the Tulsa area can be found on line at: http://www.deq.state.ok.us/AQDnew/monitoring/cpdata.htm
What are the health effects and who is most at risk?
CO enters the bloodstream through the lungs. Once in the bloodstream, it binds to red blood cells and reduces the amount of pure oxygen (O2) the blood can carry. People with cardiovascular disease are most at risk from CO. It is dangerous even to healthy people, and at lower levels people with heart disease may experience chest pain and shortness of breath. At high levels people can develop vision problems, reduced mental concentration, and difficulty performing complex tasks. Extremely high levels cause unconsciousness and death. Carbon monoxide can also contribute to the formation of smog, which can also trigger serious respiratory problems. Back to Top
Nitrogen oxides, or NOx, is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Many of the nitrogen oxides are colorless and odorless. However, one common pollutant, nitrogen dioxide (NO2) along with particles in the air can often be seen as a reddish-brown layer over many urban areas. Nitrogen oxides form when fuel is burned at high temperatures, as in a combustion process. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels.
It is interesting to note that, since 1970 when the Clean Air Act was passed, emissions of all of the criteria pollutants have decreased significantly on a national level, except for NOx, which has increased by approximately 10 percent.
Nitrogen oxides are highly reactive. When NOx and volatile organic compounds react with sunlight and heat, ground-level ozone is formed, which can cause lung tissue damage and respiratory problems. NOx, sulfur dioxide, and other substances react to form acid rain. Ammonia, moisture, and other particles combine with NOx, forming nitric acid and other particles that also can damage the respiratory system. Reactions with common organic chemicals form other toxic compounds.
NOx and the pollutants formed from NOx can be transported over long distances, following the pattern of prevailing winds in the U.S. This means that problems associated with NOx are not confined to areas where NOx are emitted. Therefore, controlling NOx is often most effective if done from a regional perspective, rather than focusing on sources in one local area.
Nitrogen dioxide (NO2) and nitrate particles are visible as a reddish-brown haze over urban areas and popular national parks, such as the Grand Canyon. Finally, nitrous oxide is a greenhouse gas, accumulating in the atmosphere with other greenhouse gasses and is thought to be a factor in global warming.
NOx emissions, carried in the air, are redeposited in precipitation. When this precipitation falls on water bodies, the nitrogen increases the nutrient loading, upsetting chemical balances and causing eutrophication, an increase in algal growth which ultimately reduces oxygen content in water bodies.
The ODEQ monitors NOx levels in the Tulsa area, and the area is in compliance of the NAAQS for nitrogen oxides. Real-time NOx monitoring data of the Tulsa area can be found on line at: http://www.deq.state.ok.us/AQDnew/monitoring/cpdata.htm
What are the health effects, and who is most at risk?
NOx causes a wide variety of health and environmental impacts because of various compounds and derivatives in the family of nitrogen oxides, including nitrogen dioxide, nitric acid, nitrous oxide, nitrates, and nitric oxide.
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· In children and adults with respiratory disease, such as asthma, nitrogen dioxide can cause respiratory symptoms such as coughing, wheezing, and shortness of breath. Even short exposures to nitrogen dioxide affect lung function.
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· In children, short-term exposure can increase the risk of respiratory illness.
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· Animal studies suggest that long-term exposure to nitrogen dioxide may increase susceptibility to respiratory infection and may cause permanent structural changes in the lungs.
Sulfur
dioxide,
or SO2,
belongs to the family of sulfur oxide gases (SOx). Sulfur is present in
raw materials such as coal, crude oil, and metal ores. When these
materials are burned, when gasoline is extracted from oil, or when
metals are extracted from ores, sulfur oxide gases (SOx) are
released. Sulfur
dioxide (SO2)
dissolves in water vapor, forming acid, and reacts with other chemicals
and particles to form sulfates and other products that can be harmful to
people and their environment.
Most SO2 is released as a by-product of electricity production in coal burning electrical plants.
Sulfur dioxide irritates respiratory systems and is especially harmful to children and the elderly and to those with existing heart and lung diseases. Short-term peak levels of SO2, such as that which accumulates during the day, cause respiratory problems for asthma sufferers.
Because SOx can be carried long distances by the wind, effects are not confined to urban areas. The acid that forms when SO2 dissolves in water falls as acid rain, damaging crops, buildings, and statuary, and acidifying bodies of water. Reactions with particles in the air reduce visibility. Sulfur oxides are another significant factor in the haze that is present above cities and at popular national parks.
The ODEQ monitors SO2 levels in the Tulsa area, and the area is in compliance of the NAAQS for sulfur dioxide. Real-time SO2 monitoring data of the Tulsa area can be found on line at: http://www.deq.state.ok.us/AQDnew/monitoring/cpdata.htm
Thirty years ago, the major source of lead in the atmosphere was from leaded gasoline used in cars and trucks. It was originally added to prevent engine knock, but researchers began to show the widespread deposition of lead on soil and in the water caused a subsequent rise in lead levels among children and wildlife. Children and infants are the most severely affected by lead contamination. Lead poisoning damages organs such as the kidneys and liver and may lead to osteoporosis (thinning bones). It also affects the brain and nervous system, causing mental retardation, memory problems, and behavior disorders. Exposure to lead can lead to high blood pressure and increase heart disease. Animals and fish can ingest lead, leading to health problems such as reproductive damage. Eating lead-contaminated fish and shellfish also increases blood levels in humans.
In the early 1970’s, the EPA mandated a gradual reduction of lead in gasoline. Today leaded gasoline has been completely banned in the United States. During the last 30 years, lead in the environment has declined from 220,000 tons to about 3900 tons. Today the major sources of lead are from metals processing, particularly lead smelters and lead acid battery manufacturers, fuel combustion, and waste disposal.
Ozone (O3) is a highly reactive form of oxygen, and at normal ambient concentrations it is colorless and odorless. At very high concentrations, O3 is a blue, unstable gas with a pungent odor. Unlike the other criteria pollutants, O3 is not emitted directly into the air by specific sources. O3 leads a dual life: in the stratosphere, it blocks most of the harmful ultraviolet (UV) rays from reaching the earth’s surface. But in the troposphere, near the surface, it is a pollutant.
Both good and bad ozone are the same molecule, consisting of three oxygen atoms. Surface ozone is a secondary pollutant, formed when NOx and volatile organic compounds react in the presence of heat and sunlight.
There are many sources of NOx and VOC pollutants. Some of the more common sources include: vehicle exhaust, gasoline vapors, industrial emissions, chemical solvents, and cleaning fluids. Essentially, O3 is “good up high - bad nearby.” Ground level O3 does occur naturally from non-manmade sources, although this results in very low concentrations.
Even though O3 production is a year-round occurrence, because of differences in climate, the length of the ozone season varies from one area of the United States to another. Southern and Southwestern states may have an ozone season that lasts nearly the entire year. Peak ozone levels in the Tulsa area typically occur from mid-May through mid-September, when the chemical reactions are most stimulated by sunlight and temperature.
Ozone and the chemicals that react to form it can be carried hundreds of miles from their origins, causing air pollution over wide regions. While urban areas are known for high ozone levels, winds can carry ozone to affect towns and rural areas miles away.
Other traits of a potentially high O3 day include these items: a weekday when traffic is prevalent, a time between 11 a.m. and 5 p.m. when the sun is high, temperature is in the 80°F and above, wind is low or calm, and little or no cloud cover is present.
Ozone affects both health and welfare. It has been estimated that 90% of inhaled O3 is never exhaled. Its effects are more severe and are experienced at lower concentrations in individuals with chronic lung disease, asthma, or diseases of the heart and circulatory system.
Ozone is an irritant. It can cause permanent damage to the respiratory system, aggravating health problems such as asthma and heart conditions even at low levels. Healthy people are also affected with throat irritation, chest pains, and shortness of breath.
Humans are not alone in feeling the harmful effects of ozone. It also damages plant foliage, reducing their ability to make food and increasing their susceptibility to insect damage and disease. The EPA estimates that $500 million in crop damage occurs a year due to the effects of ozone.
The ODEQ monitors ozone levels at five locations in the Tulsa area. The area is currently in attainment of the NAAQS for ozone; however, not meeting the newly revised ozone NAAQS. EPA is expecting to make designations for the new 8-hour ozone standard by April 2004. In 1997, EPA revised standards for ozone to better reflect the new scientific health studies. These studies showed that longer-term exposures to moderate levels of ozone may cause irreversible changes in the lungs.
Stratospheric ozone is formed when UV radiation strikes oxygen (O2) molecules, splitting them apart. These free oxygen atoms then can recombine to form O3. Thus, stratospheric ozone is constantly destroyed and reformed. It blocks up to 95% of UV radiation that can cause genetic damage in organisms. Without it, there would be no life on earth.
In the 1970’s, the British Antarctic Survey recorded severe losses of the ozone layer over Antarctica. Losses occurred seasonally over the next 15 years, creating a hole (a thin area) in the ozone layer over Antarctica. Recently a hole has appeared over the Arctic. Scientists began pointing to NOx, compounds containing bromine, halocarbons, and especially chlorine-containing chlorofluorocarbons (CFCs) as culprits. All of these chemicals are from human sources such as Freon, solvents, and fire extinguishers. As these molecules are emitted into the atmosphere, they are broken down by sunlight, releasing chlorine (Cl) and bromine (Br) atoms. These molecules react with O3, destroying it. In addition, the chlorine and bromine atoms are not themselves destroyed, so they can continue to react with ozone. One chlorine or bromine atom can destroy 100,000 ozone molecules, destroying the ozone faster than it can be formed.
Although the United States banned CFC propellants in spray cans in 1978, it was the signing of the Montreal Protocol in 1987 that has had the most significant effect on the reduction of CFCs. Over 160 countries agreed to ban the use of CFCs; and if all countries comply with the treaty, scientists estimate ozone levels should be back to normal by the year 2050. Back to Top
Organic compounds are those that contain carbon, which is present in all life. Volatile organic compounds easily vaporize (turn to gas) in the atmosphere and are an important component in smog and ground level ozone formation. VOCs can be from natural sources, and are also anthropogenic, or man-made. Sources include gasoline, industrial chemicals such as benzene, solvents such as toluene, and perchloroethylene (used in dry cleaning). VOCs are released by burning fuel, coal, wood, and exposing chemicals such as benzene to the air. Most VOCs are regulated by the EPA as hazardous air pollutants (HAPs) due to their health effects.
The major
man-made contributors to VOCs include vehicle, point and area sources.
Point sources are from a specific industrial emission source, such a
factory or a refinery. Area source emissions come from generally smaller
anthropogenic activities that are common and dispersed within a
geographic area; such as dry cleaners, paint shops, copy shops, and gas
stations. Nationally, point and area sources combined emit
approximately 50% of all anthropogenic contributing VOCs into the
atmosphere. Tulsa area’s VOC emissions from point and area sources are
estimated to be 48% of the area’s total VOCs, comparable with the
national average. 
On-road vehicles produce VOC emissions from both tailpipes and through fuel evaporation. 42% of all Tulsa area VOCs are estimated to come from on-road vehicles such as cars and trucks. Vehicles are much less polluting today than years ago, and in a general sense, a vehicle’s emission is directly related to its energy efficiency.
At some point in its lifecycle, every living organism emits some VOCs. These compounds are referred to as biogenic VOCs, which include a set of different chemicals, each having distinctive chemical properties that differ from those produced by man-made contributions. While it is difficult to assess, current research estimates that the amount of VOCs emitted by biologic and natural resources equals or exceed anthropogenic VOC levels on a global scale.
Nationally, the dominant natural source of VOCs as non-methane hydrocarbons (NMHC) is considered to be vegetation. In fact, vegetation is estimated to produce about 98% of the total natural source VOCs. This includes trees, crops, shrubs, and grasses (Berryman, 2003).
Since the last decade, experts have realized the need to consider biogenic VOC emissions in the air shed inventories used to develop emission control strategies. For this reason, several different biogenic models exist to estimate and quantify emissions from plant and soil sources in a particular area. However, while vegetative species presumably emit a large portion of all VOC ozone-forming compounds, it would not be practical or feasible to rid any area of its vegetation in order to lower ground-level ozone.
An accurate assessment of biogenic VOC influence on an area’s air shed plays an important role, however, in the development of other clean-air strategies.
Biogenic
emissions is a new and upcoming area of concern for Tulsa
and local research in this area is currently sparce. It is estimated
that natural biogenic emissions contribute much to the total VOC mix. A
1995 ODEQ emissions inventory for the Tulsa area, which included a
modeled estimate of VOC contributions
from biogenic sources, hinted that as much as 62% of all Tulsa’s VOC
emissions may come from natural biogenic sources.
The Eastern Red Cedar tree, seen here at the right, has been increasing rapidly. This Tulsa-native tree species can emit nearly twice the VOC concentration as many other tree and vegetation varieties.
For the United States, natural source VOCs are estimated to be higher than anthropogenic source VOCs, and the Southeastern and South Central portions of the United States account for approximately 43% of the national natural NMHC estimate. Forests and agriculture contribute the largest share of biogenic VOC emissions because they are concentrated spots of large BVOC-producing organisms.