What are you breathing?

The U.S. Environmental Protection Agency (EPA) tracks 6 major air pollutants that cause major health effects:

• Ground-level ozone

• Nitrogen dioxide

• Sulfur dioxide

• Carbon monoxide

• Lead

• Microscopic particles called particulate matte

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 such as carbon monoxide or nitrogen dioxide, the cells that line the airways to the lungs absorb them. Once taken in, the gases can pass into your blood and travel to your internal organs. There they can cause damage. If the pollution isn't absorbed into the blood, damage can still be done to the lungs.

Large particles in the air are filtered out by the small hairs (cilia) that line your respiratory tract. But smaller particles reach your airways and lungs. Particles of all sizes also land on crops and in water. Over time they are eaten by humans, and by animals that humans eat.

Health effects

The effects of air pollution vary from person to person. A healthy adult who is exposed to these pollutants for a short time or at low dose may not have long-term problems. But it's different for people with a heart or respiratory condition. For these people, even a small dose or a short exposure can make symptoms worse. Longer exposure or a higher dose can lead to serious illness. In some cases it can lead to death. Children and older adults are more likely to be affected by air pollution than others. They can suffer the effects at lower pollution levels.

Air Quality Index

The Air Quality Index (AQI) is a national index for 6 major air pollutants regulated by the Clean Air Act:

• Ground-level ozone

• Particle pollution

• Carbon monoxide

• Lead

• Sulfur dioxide

• Nitrogen dioxide

The index tells you how clean or polluted your air is. It also tells you what health effects you may have in a few hours or days after breathing polluted air.