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Air pollution is the black cloud belching from an industrial smokestack. It's the smog that settles over certain cities, dimming the skyline. It's the smelly exhaust of an old car that burns oil.
Air pollution also can be invisible, causing lung damage, cancer, or other serious health problems in people who may not realize the potential danger of the unseen gases or particles suspended in the air.
The U.S. Environmental Protection Agency (EPA) tracks six major air pollutants that cause significant health effects: ground-level ozone, nitrogen oxides, sulfur oxides, carbon monoxide, lead, and microscopic particles called particulate matter. Both the outside air and the air in your home or workplace can have these pollutants. The amount of pollutant in the air and the length of time you are exposed to it determine how the pollutant will affect you.
When you breathe in gases like carbon monoxide or nitrogen dioxide, they are absorbed by the cells that line the airways to the lungs. Once absorbed, the gases can pass into the bloodstream and travel to your internal organs, where they can cause damage. If the pollution isn't absorbed into the blood stream, then damage can still be done to the lungs themselves.
Large particles in the air are filtered out by cilia, the small hairs that line your respiratory tract. Smaller particles, however, reach your airways and lungs. Particles of all sizes also land on crops and in water and are eventually consumed by humans and by animals that humans eat.
The effects of air pollution differ from person to person. A healthy adult who is exposed to these pollutants for a short time or at low dose may not develop long-term problems. For a person with a heart or respiratory condition, however, even a small dose or a short exposure can make symptoms worse. Longer exposure or a higher dose can lead to serious illness and, in some cases, death. Children and the elderly are more susceptible to air pollution than other individuals and can suffer the effects at lower pollution levels.
The Air Quality Index (AQI) is a national index for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide. The index tells you how clean or polluted your air is, and what you may experience within a few hours or days after breathing polluted air. For more information about AQI, go to http://www.airnow.gov/.