Assessing Outdoor Air Near Schools
Key pollutants measured varied by school and were selected based on emission sources in the vicinity of each school.
|Pollutant Groups||Key Pollutants of Particular Interest
Links to Background and Health Information
(Polycyclic Aromatic Hydrocarbons)
(Volatile Organic Compounds)
The pollutant groups include both individual pollutants within the group that our current information indicates may be present at each school at levels of potential concern (i.e., pollutants of particular interest or "key pollutants") and some other pollutants that can be inexpensively measured at the same time. While we will be analyzing air samples for both sets of pollutants in each chemical group and will review all the data in drawing conclusions for each school, we intend to focus our data analysis activities primarily on the individual "driver pollutants".
Metals are suspended in the air as tiny particles. EPA is using two different methods to sample for metals in the air around schools. The first method “PM10” captures only smaller particles that can be inhaled and enter the lungs – those that are 10 micrometers in diameter or smaller. The other method collects total suspended particles (TSP).
The choice of method depends on the key pollutants we expect to find around a school.
- At schools where we are interested in levels of metals other than lead, we measured the concentrations of metals in PM10 samples. Our assessment of potential health concerns from these metals in the air is focused on inhalation. PM10 samples provide a better estimate for that than the larger TSP samples.
- At schools where we are interested in levels of lead in the air, we measured the concentrations of lead in TSP samples. Our assessment of potential health concerns for airborne lead includes non-inhalation exposure pathways, such as incidental ingestion of dust from the air that can be picked up onto children’s hands. Particles collected in the larger TSP samples can play an important role in these exposures. EPA’s National Ambient Air Quality Standards, which are the sample screening levels for lead used in this initiative, are based on lead in TSP samples.
- At schools where we are interested in levels of lead and other metals, we collected both PM10 and TSP samples.
Information on Key Pollutants
Chromium occurs naturally in rocks, animals, plants, and soil. It can exist in several different forms. Depending on the form it takes, it can be a liquid, solid, or gas. The form of chromium of most concern from a health perspective is chromium(VI), also called hexavalent chromium. Inhalation of hexavalent chromium at high levels can damage the respiratory system and cause cancer. Other forms of chromium are chromium(0) and chromium(III). Chromium(0) is the metal form of chromium. It is used in steel manufacturing. Hexavalent chromium and chromium(III) are used for chrome plating, dyes and pigments, leather tanning, and wood preserving. Chromium(III) is an essential nutrient that helps the body use sugar, protein, and fat. Exposure to chromium occurs from ingesting contaminated food or drinking water or breathing contaminated air. It is odorless and tasteless. Air emissions of chromium are predominantly of chromium(III), and in the form of small particles or aerosols. The largest industrial sources of chromium in the atmosphere are those related to ferrochrome production. Ore refining, chemical and refractory processing, cement-producing plants, automobile brake lining and catalytic converters for automobiles, leather tanneries, and chrome pigments are also sources of chromium emissions to ambient air.
Manganese occurs naturally. A small amount is necessary for you to stay healthy. Manganese can be released into the air by iron and steel production plants, power plants, and coke ovens. Exposure to excess levels of manganese can most commonly occur from breathing air in areas impacted by industrial sources of manganese. The most common health problems in workers exposed to high levels of manganese involve the nervous system. These health effects include behavioral changes and other nervous system effects, which include movements that, with high exposures, may become slow and clumsy.
Arsenic is a naturally occurring element widely distributed in the earth’s crust. Inorganic forms of arsenic is found throughout the environment; it is released into the air by volcanoes, the weathering of arsenic-containing minerals and ores, and by commercial or industrial processes. Workers in metal smelters and nearby residents may be exposed to elevated inorganic arsenic released into the air. Other air sources of inorganic arsenic exposure include burning plywood treated with an arsenic wood preservative. Acute (short-term) high-level inhalation exposure to arsenic dust or fumes can cause gastrointestinal effects (nausea, diarrhea, abdominal pain) and nervous system disorders. Chronic (long-term) inhalation exposure to inorganic arsenic can cause irritation of the skin and mucous membranes and lung cancer.
Cobalt is a naturally occurring element found in rocks, soil, water, plants, and animals. Cobalt is beneficial for humans because it is part of vitamin B12. Cobalt is used to produce alloys used in the manufacture of aircraft engines, magnets, grinding and cutting tools, artificial hip and knee joints. Cobalt compounds are also used to color glass, ceramics and paints, and used as a drier for porcelain enamel and paints. Exposure to high levels of cobalt can result in respiratory effects. Such effects, as well as effects on heart, liver and kidney effects have also been noted in people who have worked for long periods of time in industries where they were exposed to cobalt.
Nickel is a naturally occurring element. Pure nickel is a hard, silvery-white metal used to make stainless steel and other metal alloys. Nickel can be combined with other metals, such as iron, copper, chromium, and zinc, to form alloys. These alloys are used to make coins, jewelry, and items such as valves and heat exchangers. Most nickel is used to make stainless steel. Nickel can be released into ambient air from oil and coal combustion, nickel metal refining, sewage sludge incineration, manufacturing facilities, and other sources. Respiratory effects are associated with chronic exposure to nickel in the air. Workers who breathed very large amounts of nickel compounds developed chronic bronchitis and lung and nasal sinus cancers.
Acetaldehyde is ubiquitous in the environment and may be formed in the body from the breakdown of ethanol. It is formed from wood combustion in fireplaces and woodstoves, coffee roasting, burning of tobacco, vehicle exhaust fumes, and coal refining and waste processing. Hence, many individuals are exposed to acetaldehyde by breathing ambient air. Acute (short-term) exposure to acetaldehyde results in effects including irritation of the eyes, skin, and respiratory tract. Symptoms of chronic (long-term) intoxication of acetaldehyde resemble those of alcoholism. It may also cause cancer of the upper respiratory tract.
Acrolein can enter the air when organic matter such as trees and other plants are burned and also when fuels such as gasoline and oil are burned. It can also be produced in the atmosphere from the breakdown of other chemicals and is found in emissions from some industries. It is a component of cigarette smoke. For many individuals, the primary exposure to airborne acrolein is from smoking tobacco or being near someone who is smoking. People may also be exposed to high acrolein levels from vehicle exhaust, such as in parking garages and/or areas of heavy traffic. House fires or forest fires also create situations with high acrolein levels. At high levels, exposed individuals may experience irritation of eyes, nose and throat.
Benzene is a widely used chemical formed from both natural processes and human activities. It ranks in the top 20 chemicals for production volume. Some industries use benzene to make other chemicals which are used to make plastics, resins, and nylon and other synthetic fibers. Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. Benzene is also a natural part of crude oil, gasoline, and cigarette smoke. Benzene is found in airborne emissions from burning coal and oil, motor vehicle exhaust, and evaporation from gasoline service stations and in industrial solvents. These sources contribute to elevated levels of benzene in the ambient air, which may subsequently be breathed by the public. Tobacco smoke contains benzene and accounts for nearly half the national exposure to benzene. Breathing very high levels of benzene can cause drowsiness, dizziness, and unconsciousness; long-term benzene exposure causes effects on the bone marrow and can cause anemia and leukemia.
Motor vehicle exhaust is a constant source of 1,3-butadiene. Although 1,3-butadiene breaks down quickly in the atmosphere, it is usually found in ambient air at low levels in urban and suburban areas. Acute (short-term) exposure to 1,3-butadiene by inhalation in humans results in irritation of the eyes, nasal passages, throat, and lungs. Epidemiological studies have reported a possible association between 1,3-butadiene exposure and cardiovascular diseases. Epidemiological studies of workers in rubber plants have shown an association between 1,3-butadiene exposure and increased incidence of leukemia.
PAHs and Benzo(a)pyrene [BaP]
Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are also found in coal tar, crude oil, creosote, and roofing tar, and a few are used in medicines or to make dyes, plastics, and pesticides. PAHs are usually found as a mixture containing two or more of these compounds, such as in soot. Benzo (a) pyrene (BAP) is the most well-studied of these compounds and long-term repeated exposure to BaP has been found to cause cancer.