Air toxics are a group of air pollutants that are known or suspected to cause serious health problems. Examples of air toxics include asbestos, benzene, chloroform, formadehyde, lead, mercury and nickel compounds, and perchloroethylene. more

People exposed to air toxics at sufficient concentrations and durations may have an increased chance of developing cancer or other serious health problems including damage to the immune system as well as neurological, reproductive (reduced fertility), developmental, and respiratory problems. Like humans, animals also may experience health problems if exposed to sufficient quantities of air toxics over time.

 How are people exposed to air toxics?

People are exposed to toxic air pollutants in many ways such as:

• Breathing contaminated air
• Eating contaminated food products, such as fish from contaminated waters; meat, milk, or eggs from animals that fed on contaminated plants; and fruits and vegetables grown in contaminated soil on which air toxics have been deposited
• Drinking water contaminated by toxic air pollutants
• Ingesting contaminated soil. Young children are especially vulnerable because they often ingest soil from their hands or from objects they place in their mouths
• Touching (making skin contact with) contaminated soil, dust, or water (for example, during recreational use of contaminated water bodies)

Once toxic air pollutants enter the body, some persistent toxic air pollutants accumulate in body tissues. Since predators typically accumulate even greater pollutant concentrations than their contaminated prey, people and other animals at the top of the food chain may be exposed to higher concentrations of toxics than are found in water, air, or soil alone.

 For More Information

The Health Effects Notebook for Hazardous Air Pollutants

EPA fact sheets on the health effects of nearly every hazardous air pollutant specified in the Clean Air Act Amendments of 1990.

Taking Toxics Out of the Air

EPA publication describing what air toxics are, where they come from, and how they impact people and the environment.

Air Pollution and Health Risk (English) I Spanish

EPA's Web site explaining how it determines when a risk from a hazardous substance is serious. Learn how researchers estimate risk, and how the government uses this information to develop regulations that limit exposure to hazardous substances.

Evaluating Exposures to Toxic Air Pollutants: A Citizen's Guide (English) I Spanish

Explains the process EPA uses to determine the level and extent of exposure to toxic air pollution.

Risk Assessment for Toxic Air Pollutants: A Citizen's Guide (English) I Spanish

EPA's guide to risk assessment, which is the process used to estimate the risk of illness from human exposure to a specific toxic air pollutant.

Asbestos is a mineral fiber that can only be identified with a special type of microscope. In the past, various types of asbestos fibers were added to a variety of products to strengthen them and to provide heat insulation and fire resistance.

Most people are exposed to small amounts of asbestos in their daily lives and do not develop health problems. When disturbed, however, asbestos can become an air toxic, releasing fibers which can be inhaled or ingested. Asbestos fibers may be released into the air by the disturbance of asbestos-containing material during product use, demolition work, building or home maintenance, repair, and remodeling. Asbestos fibers can remain in the lungs for a long time, increasing the risk of disease.

Studies of people who were exposed to asbestos in factories and shipyards have shown that breathing high levels of asbestos fibers can lead to an increased risk of:

• lung cancer;

• mesothelioma, a cancer of the lining of the chest and the abdominal cavity; and

• asbestosis, in which the lungs become scarred with fibrous tissue.

Researchers have not yet determined a safe level of exposure, but know that the greater and longer the exposure, the greater risk of the contracting an asbestos-related disease. Risks of lung cancer and mesothelioma increase with the number of fibers inhaled. The risk of lung cancer from inhaling asbestos fibers is also greater for smokers. People who develop asbestosis have usually been exposed to high levels of asbestos for a long time. The symptoms of these diseases do not usually appear until about 20 to 30 years after the first exposure to asbestos.

 For More Information

EPA's Asbestos Web Site

Health effects of exposure to asbestos, explanations of laws and regulations that govern asbestos use, and lists of asbestos information resources and contacts.

Asbestos: Health and Exposure

A pdf publication of the EPA Office of Air Quality Planning Standards.

EPA Region 10 Asbestos Web Site

Asbestos information specific to the Pacific Northwest, including Idaho.

EPA Region 10 Asbestos Coordinator

Raymond Nye, (206) 553-4226; nye.raymond@epa.gov

Asbestos Abatement and Disposal in Idaho

DEQ's Web page on EPA regulation of asbestos removal and disposal projects in Idaho.

Carbon monoxide (CO) is a colorless, odorless, and poisonous gas and one of six "criteria pollutants" for which EPA has established protective standards. Carbon monoxide forms when the carbon in fuels does not completely burn. Vehicle exhaust contributes roughly 60% of all CO emissions nationwide and up to 95% in cities. Other sources include fuel combustion in industrial processes and natural sources such as wildfires. Carbon monoxide concentrations typically are highest during cold weather because cold temperatures make combustion less complete and cause inversions that trap pollutants low to the ground.

Carbon monoxide enters the bloodstream through the lungs and binds chemically to hemoglobin, the substance in blood that carries oxygen to cells. In this way, CO interferes with the ability of the blood to transport oxygen to organs and tissue throughout the body. This can cause slower reflexes, confusion, and drowsiness. It can also reduce visual perception and coordination and decrease the ability to learn. People with cardiovascular disease, such as angina, are most at risk from exposure to CO. These individuals may experience chest pain and more cardiovascular symptoms if they are exposed to CO, particularly while exercising.

Hydrogen sulfide is a colorless, transparent gas with a characteristic rotten-egg odor at low concentrations and no detectable odor at high concentrations. Odors become detectable in concentrations as low as .008 parts per million (ppm), according to studies conducted in California.

Hydrogen sulfide is an extremely toxic and irritating gas. Free hydrogen sulfide in the blood reduces its oxygen-carrying capacity, thereby depressing the nervous system. Because hydrogen sulfide is oxidized quite rapidly to sulfates in the body, however, acute exposure has not been shown to produce permanent aftereffects, unless oxygen deprivation of the nervous system is prolonged. Repeated exposures to hydrogen sulfide also are not believed to result in accumulative or systemic poisoning. Effects such as eye irritation, respiratory tract irritation, slow pulse rate, lassitude, digestive disturbances, and cold sweats may occur, but these symptoms typically disappear in a relatively short time after removal from exposure.

For further information on the health effects of low-level exposure to hydrogen sulfide, read a Literature Review of the Health Effects Associated with the Inhalation of Hydrogen Sulfide (DEQ Publication, June 2001: pdf 49 kb, 15 pages).

Most people are aware that outdoor air pollution can damage their health, but knowledge of the health impacts of indoor air pollution is limited. EPA studies of human exposure to air pollutants indicate that indoor levels of pollutants may be 2 to 5 times higher, and occasionally more than 100 times higher, than outdoor levels. These levels of indoor air pollutants may be of particular concern because most people spend about 90% of their time indoors.

 Sources of Indoor Air Pollutants

Many sources of indoor air pollution can be found in any home, including:

• combustion sources such as oil, gas, kerosene, coal, wood, and tobacco products;
• building materials and furnishings as diverse as deteriorated, asbestos-containing insulation, wet or damp carpet, and cabinetry or furniture made of certain pressed wood products;
• products for household cleaning and maintenance, personal care, or hobbies;
• central heating and cooling systems and humidification devices; and
• outdoor sources such as radon, pesticides, and outdoor air pollution.

The relative importance of any single source depends on how much of a given pollutant it emits and how hazardous those emissions are. In some cases, factors such as how old the source is and whether it is properly maintained are signficant. For example, an impoperly adjusted gas stove can emit significantly more carbon monoxide that one that is properly adjusted.

 Immediate Effects of Exposure to Indoor Air Pollutants

Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later. Immediate effects may show up after a single exposure or repeated exposures. These include headaches, dizziness, fatigue, and irritation of the eyes, nose, and throat.

Such immediate effects are usually short-term and treatable. Sometimes the treatment is simply eliminating the person's exposure to the source of the pollution, if it can be identified. Symptoms of some diseases, including asthma, hypersensitivity pneumonitis, and humidifier fever, may also show up soon after exposure to some indoor air pollutants.

The likelihood of immediate reactions to indoor air pollutants depends on several factors. Age and preexisting medical conditions are two important influences. In other cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants as well.

Certain immediate effects are similar to those from colds or other viral diseases, so it is often difficult to determine if the symptoms are a result of exposure to indoor air pollution. For this reason, it is important to pay attention to the time and place symptoms occur. If the symptoms fade or go away when a person is away from home, for example, an effort should be made to identify indoor air pollution sources that may be possible causes. Some effects may be made worse by an inadequate supply of outdoor air or from the heating, cooling, or humidity conditions prevalent in the home.

 Long-term Effects of Exposure to Indoor Air Pollutants

Other health effects from exposure to indoor air pollutants may show up either years after exposure has occurred or only after long or repeated periods of exposure. These effects, which include some respiratory diseases, heart disease, and cancer, can be severely debilitating or fatal.

It is prudent to try to improve the indoor air quality in your home even if symptoms are not noticeable. While pollutants commonly found in indoor air are responsible for many harmful effects, it is uncertain what concentrations or periods of exposure are necessary to produce specific health problems. People also react very differently to exposure to indoor air pollutants. Further research is needed to better understand which health effects occur after exposure to the average pollutant concentrations found in homes and which occur after exposure to higher concentrations for short periods of time.

 For More Information

In Idaho, the Bureau of Environmental Health and Safety of the Department of Health and Welfare is responsible for informing and educating citizens about human health risks associated with exposure to indoor contaminants and ways to prevent or reduce exposure. Visit the Bureau's Web site for information on the agency's indoor environment program and to access various fact sheets on indoor air pollution and assistance. Indoor air quality for businesses and industry is regulated by the Occupational Safety and Health Administration (OSHA).

EPA also maintains a Web site on Indoor Air Quality with information on sources of indoor air pollution, their associated health effects and ways to reduce exposure.

Lead is a metal found naturally in the environment as well as in manufactured products. It is one of six "criteria pollutants" for which EPA has established protective standards. Historically, the major sources of lead emissions were motor vehicles (such as cars and trucks) and industrial sources. Due to the phase-out of leaded gasoline, however, airborne lead is no longer a problem in most of the U.S. The major source of lead emissions today is metals processing and the highest levels of lead in air are generally found near lead smelters, waste incinerators, utilities, and lead-acid battery manufacturers.

Exposure to lead can occur through multiple pathways, including inhalation of air and ingestion of lead in food, water, soil, or dust. Excessive lead exposure can cause seizures, brain and kidney damage, mental retardation and/or behavioral disorders. Children six and under are most at risk because their bodies are growing quickly. Research suggests that the primary sources of lead exposure for most children are deteriorating lead-based paint, lead-contaminated dust, and lead-contaminated residential soil.

 For More Information

Lead in Paint, Dust, and Soil (EPA Web Page)
Information on all aspects of the federal lead poisoning prevention program, with a special focus on the efforts within EPA's Office of Pollution Prevention and Toxics.

Protect Your Family From Lead in Your Home (EPA pdf Publication)
This publication, issued jointly by EPA and the U.S. Consumer Product Safety Commission, provides information on detecting possible lead hazards in the home, what to do if hazards are found, effects of lead in the body, and advice on how to significantly reduce lead hazards.

Lead - How Lead Affects the Way We Live and Breathe (EPA Web Page)
Today, metal processing plants are generally responsible for most of the lead in the air.

Mercury is a naturally occurring element present throughout the environment. When released into the air as a result of human activity, it can become an air toxic. Mercury concentrations in air are usually low, however, and of little direct concern. In the U.S., coal-fired power plants are the primary source of mercury emissions to the air.

Human activity can release mercury into the water and soil as well. When mercury enters water, biological processes transform it to a highly toxic form that builds up in fish and animals that eat fish. People are exposed to mercury primarily by eating fish. Link to more information about Mercury in the Environment.

Nitrogen dioxide is a brownish, highly reactive gas present in all urban atmospheres. Nitrogen dioxide is a "criteria pollutant" that can irritate the lungs, cause bronchitis and pneumonia, and lower resistance to respiratory infections. Nitrogen oxides contribute to formation of both ozone and acid rain and may affect both terrestrial and aquatic ecosystems. The major mechanism for the formation of nitrogen dioxide in the atmosphere is the oxidation of the primary air pollutant nitric oxide. Nitrogen oxide forms when fuel is burned at high temperatures.

The two major emission sources of nitrogen oxides are automobiles and stationary fuel combustion sources such as electric utility and industrial boilers.

Health effects of exposure to nitrogen dioxide include:

• In children and adults with respiratory disease such as asthma, nitrogen dioxide can cause coughing, wheezing, and shortness of breath. Even short exposures to nitrogen dioxide can affect lung function.

• In children, short-term exposure can increase the risk of respiratory illness.

• 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.

 For More Information

NOx: How Nitrogen Oxides Affect the Way We Live and Breathe (EPA Web Page)

Information on how nitrogen oxides are formed, health and environmental impacts, and efforts to reduce NOx.

Ozone is a gas that forms in the atmosphere when three atoms of oxygen are combined. It is not emitted directly into the air, but is created at ground level by a chemical reaction between oxides of nitrogen, and volatile organic compounds in the presence of sunlight. Ozone has the same chemical structure whether it occurs high above the earth or at ground level and can be "good" or "bad," depending on its location in the atmosphere.

Ozone occurs in two layers of the atmosphere. The layer surrounding the earth's surface is the troposphere. Here, ground-level or "bad" ozone is an air pollutant that damages human health, vegetation, and many common materials. It is a key ingredient of urban smog. The troposphere extends to a level about 10 miles up, where it meets the second layer, the stratosphere. The stratospheric, or "good" ozone layer, extends upward from about 10 to 30 miles and protects life on earth from the sun's harmful ultraviolet rays.

The reactivity of ozone causes health problems because it damages lung tissue, reduces lung function, and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of ozone not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to ozone for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing, and pulmonary congestion.

Recent health studies have shown ozone to be even more detrimental to health than previously thought. The EPA has issued new, more stringent standards for this "criteria pollutant" based on these studies.

 For More Information

Ground Level Ozone: Protecting Your Health and Air Quality

(DEQ Brochure, June 2008: 375 kb, 2 pages)

Ozone: Good Up High, Bad Nearby (EPA Web Page)
Ozone is a gas that forms in the atmosphere when three atoms of oxygen are combined.

Smog: Who Does It Hurt?: What You Need To Know About Ozone and Your Health
(EPA Web Page)

On a hot, smoggy summer day, have you ever wondered: Is the air safe to breathe? Should I be concerned about going outside?

Particulate matter, or PM, is the term for small particles found in the air including dust, dirt, soot, smoke, and liquid droplets. 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 detected with an electron microscope. Some particles are directly emitted into the air while others are formed in the air through chemical reactions. Sources of PM include cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, construction, wood burning, agricultural burning, wildfires, prescribed fires, and natural windblown dust.

Particulate matter is a "criteria pollutant" that comes in a wide range of sizes. Particles less than 10 micrometers in diameter 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 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.

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).

• 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.

• Older persons are especially sensitive to PM exposure. They are at increased risk of admission to hospitals or emergency rooms and premature death from heart or lung diseases.

• 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.

• 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.

 For More Information

PM - How Particulate Matter Affects the Way We Live and Breathe (EPA Web Page)
More than 20 million people live in areas with PM concentrations that were above the national standard in 1999.

Sulfur dioxide is a colorless, reactive gas produced during burning of sulfur-containing fuels such as coal and oil, during metal smelting, and by other industrial processes. Sulfur dioxide emitted to the atmosphere results largely from stationary sources such as coal and oil combustion, steel mills, refineries, pulp and paper mills, and nonferrous smelters. Generally, the highest concentrations of this "criteria pollutant" are found near large industrial sources, such as power plants and industrial boilers.

High concentrations of sulfur dioxide affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children, and the elderly. Sulfur dioxide is also a primary contributor to acid rain, which causes acidification of lakes and streams and can damage trees, crops, buildings, and statues. In addition, sulfur compounds in the air contribute to visibility impairment in large parts of the country. This is especially noticeable in national parks.

 For More Information

SO2 - How Sulfur Dioxide Affects the Way We Live and Breathe (EPA Web Page)

EPA has established standards for six air pollutants known as "criteria pollutants" to protect the health and welfare of people, plants, and animals, as well as to prevent damage to buildings, monuments, water resources, and natural areas. Standards for criteria pollutants are based on current scientific data and studies, and are designed to protect the most sensitive populations. Those most likely to be affected by air pollution include the elderly, children, and people with existing respiratory problems. It also includes active, healthy adults who work or exercise outdoors. The standards are revised every five years to reflect new studies and scientific data on health impacts.