Dear Reader,

Stinky air and dirty skies — air pollution causes unpleasant sights and smells, but it can have more serious effects as well. Air pollution — a general term referring to excessive or harmful amounts of certain substances in the air — has been linked to serious health problems, such as cancer, infertility, and birth defects. Air pollution is largely a result of human activity: cars, power plants, and factories are just a few of the sources of harmful chemicals in the air.

Air pollution affects us when we breathe, but it reaches us in other ways as well. Polluted air can contaminate land and bodies of water with toxic chemicals. Plants or crops that grow in contaminated land also carry these chemicals and pass them onto animals that eat them. In this way, toxic chemicals enter our bodies through the food we eat and the water we drink.

Some of the most common chemicals that pollute the air are:

Nitrogen oxides are gases that are formed when fossil fuels (such as oil, gasoline, and coal) are burned at high temperatures. These gases mostly come from cars and trucks, power plants, and factories. Nitrogen oxides contribute to a number of problems:

• Ground-level ozone (a.k.a. smog, a combination of smoke and fog) is created by reactions between nitrogen oxides, sunlight, and other chemicals in the air. Smog can damage lung tissue and reduce lung efficiency. It can also damage crops and vegetation.
• Acid rain happens when nitrogen oxides combine with sulfur dioxide (a chemical that also comes from burning fossil fuels — more info on this a little further down) and react with other chemicals to create acid in the atmosphere. When this acid falls through rain, snow, or fog, it contaminates farmland and bodies of water.
• Global warming happens when nitrous oxide collects in the atmosphere with other gases, causing a gradual rise in the earth's temperature. Global warming may also change weather patterns, which could hurt farming and food production and, according to some scientists, facilitate the spread of certain diseases. For more information on the risks of global warming, check out the U.S. Environmental Protection Agency's (EPA) Global Warming Page.

Sulfur dioxide is a gas that is formed when sulfur-rich fuels (such as oil and coal) are burned, when oil is processed to produce gasoline, and/or when ores are processed to produce metals. As mentioned earlier, sulfur dioxide can react to form acid rain. The chemical can also gather in the lungs, aggravate pre-existing health conditions, and cause breathing problems.

Carbon monoxide is a gas that comes from cars and trucks that burn fossil fuels, factories, and wood burning. The chemical interferes with the body's normal delivery of oxygen to its organs, and in high levels, carbon monoxide is poisonous to humans. Lower levels can affect the central nervous system, resulting in vision problems, trouble learning and performing complicated tasks, and decreased dexterity. Carbon monoxide can have particularly harmful effects on individuals with heart disease, such as angina or clogged arteries. Even low levels of the chemical can cause chest pain and reduced ability to exercise.

Air pollution and global warming are complicated and sometimes controversial topics. If you're interested in learning more, many resources are available. The EPA has a number of web pages that can help you evaluate the risks you and your community face from air pollution:

• Risk assessment for toxic air pollutants: A citizen's guide
• Evaluating exposures to toxic air pollutants: A citizen's guide

You can also look for more information on the National Institutes of Health's Air Pollution Page.

Many organizations are politically active and focus on air pollution and global warming. Some try to convince politicians to make laws that they think will make the air cleaner, while others teach people ways to pollute less and inform the public about pollution-related health risks. To find out more, check out the Sierra Club's Global Warming Campaign and the Natural Resources Defense Council (NRDC). Some organizations can take radical stances on environmental issues, so do some research before you get involved with them.

Individuals can reduce air pollution and the health problems it causes by:

• driving cars that get good gas mileage, including gas-electric hybrid cars.
• carpooling, biking, and taking public transit whenever possible.
• using efficient, long-lasting fluorescent light bulbs.

For more on steps you can take to reduce air pollution, take a look at the NRDC's How To Fight Global Warming web page.

Alice

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