Air pollution is responsible for major health effects.  Every year, the health of countless people is ruined or endangered by air pollution.

Many different chemicals in the air affect the human body in negative ways.  Just how sick people will get depends on what chemicals they are exposed to, in what concentrations, and for how long.

Studies have estimated that the number of people killed annually in the US alone could be over 50,000.

Older people are highly vulnerable to diseases induced by air pollution.  Those with heart or lung disorders are under additional risk.  Children and infants are also at serious risk.

Because people are exposed to so many potentially dangerous pollutants, it is often hard to know exactly which pollutants are responsible for causing sickness.  Also, because a mixture of different pollutants can intensify sickness, it is often difficult to isolate those pollutants that are at fault.

Many diseases could be caused by air pollution without their becoming apparent for a long time.  Diseases such as bronchitis, lung cancer, and heart disease may all eventually appear in people exposed to air pollution.

Air pollutants such as ozone, nitrogen oxides, and sulfur dioxide also have harmful effects on natural ecosystems.  They can kill plants and trees by destroying their leaves, and can kill animals, especially fish in highly polluted rivers.