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| Home > Issues & Actions: Air Quality and Human Health |
Air Pollution and Human Health
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In recent years, the link between various illnesses and air pollution has become much clearer as a result of many epidemiological studies. For example, we now know that some pollutants increase human mortality, we know that smog exacerbates asthma in both children and adults, and we know that particulate matter increases the prevalence of cardiovascular disease. These are but a few of the conclusions from recent reports.
The federal Clean Air Act of 1970 set standards for six "criteria" pollutants, which were thought to be the most harmful to health and the environment. Air toxics are also regulated under the Act. Below is a summary of what is known about the effects of the six criteria pollutants and selected air toxics. There are numerous web sites devoted to explaining air pollution and its health effects, some of which are provided below.
Ground-Level Ozone
Many people think of ozone as something good that we want to protect. In the stratosphere, where it shields the earth from ultraviolet radiation, that is true. But down at the earth's surface, ozone is a powerful pollutant that can damage people's lungs and even cause premature death. Ozone is formed when two other common pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOCs), combine in the presence of sunlight and heat. Even at low levels, ozone can irritate the lungs and aggravate asthma. Repeated exposure can cause permanent lung damage. In addition, ozone interferes with plant growth and productivity, thereby impairing crop yields and damaging native vegetation.
Both St. Louis and Kansas City have struggled to meet the federal standard for ground-level ozone set in 1977. In 1997, as a result of numerous studies showing the harmful effects of ozone on people's health, the EPA developed a lower standard that will be implemented in coming years. Reductions in the pollution from automobiles, power plants and other industrial facilities will be needed to meet this standard.
Particulate Matter
Particulate matter, or "PM", consists of the dust, soot and smaller particles in the air. Some types of PM can be seen with the naked eye, such as soot or smoke, but many forms of PM are so small that a microscope is needed to see them. PM is directly emitted by a number of sources, including automobiles, fuel burning and unpaved roads, but can also be formed in the air as different chemicals react. The health effects of PM include aggravated asthma, respiratory complications and even premature death. In addition, PM impairs visibility, carries toxins into distant water bodies and can damage buildings and vegetation. The EPA also developed a new standard for PM in 1997, which will be implemented in coming years.
Carbon Monoxide
Carbon monoxide, or "CO", is a colorless, odorless gas that is formed when carbon in fuel is not burned completely. It is a component of motor vehicle exhaust, which contributes about 56 percent of all CO emissions nationwide. Higher levels of CO generally occur in areas with heavy traffic congestion. Carbon monoxide can cause harmful health effects by reducing oxygen delivery to the body's organs (like the heart and brain) and tissues.
Nitrogen Oxides
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. The primary sources of NOx are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels. When nitrogen oxides combine with other substances in the air, they form a number of very harmful chemicals, such as ozone and nitric acid. Ozone, as described above, has many harmful effects on the human body. When NOx forms acids it contributes to acid rain, which damages cars, buildings and historical monuments, and causes lakes and streams to become acidic and unsuitable for many fish.
Sulfur Dioxide
Sulfur dioxide, or "SO2", is formed when fuel containing sulfur, such as coal and oil, is burned, and when gasoline is extracted from oil. Over 65% of SO2 released to the air in the U.S., or more than 13 million tons per year, comes from electric utilities, especially those that burn coal. SO2 dissolves in water vapor to form acid, and interacts with other gases and particles in the air to form sulfates and other products that can be harmful to people and their environment. By itself, SO2 can cause temporary breathing difficulty for people with asthma and, over the long-term, can cause respiratory illness and aggravate existing heart disease. When combined with other substances in the air, SO2 forms harmful particulate matter and acid rain.
Lead
Lead is a metal found naturally in the environment, as well as in manufactured products. The major sources of lead emissions have historically been motor vehicles (such as cars and trucks) and industrial sources. Due to the phase out of leaded gasoline in the 1970s and 80s, the highest levels of lead in the air today are generally found near lead smelters. Missouri is by far the leading state for lead production, and contains the nation's largest lead smelter in Herculaneum. Both the Herculaneum smelter and the smelter in the town of Glover have had a history of air and water pollution problems. Lead pollution is known to cause damage to various organs, and may lead to mental retardation, behavioral disorders, loss of memory and mood changes.
Air Toxics
Toxic air pollutants, also known as hazardous air pollutants (HAPs), are those pollutants that are known or suspected to cause cancer or other serious health effects. EPA has identified 188 pollutants it considers toxic, including benzene, which is found in gasoline, perchlorethlyene, which is emitted from some dry cleaning facilities, and methylene chloride, which is used as a solvent and paint stripper.
Examples of other listed air toxics include dioxin, asbestos, toluene, and metals such as cadmium, mercury, chromium, and lead compounds. People exposed to toxic air pollutants may have an increased chance of getting cancer or experiencing other serious health effects.
For further information on air pollution you can call the MCE office at 314-727-0600, or visit one of the web sites below.
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St. Louis Regional Clean Air Partnership
U.S. Environmental Protection Agency |
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