What Are the Health Effects of Air Pollution?

Air pollution is the black cloud belching from an industrial smokestack. It's the smog that settles over some cities, dimming the skyline. It's the smelly exhaust of an old car that burns oil.

Air pollution can also be invisible and odorless. It can cause lung damage, cancer, or other serious health problems in people who may not realize the possible danger of the unseen gases or particles in the air.

What are you breathing?

The EPA tracks five major air pollutants that cause major health effects. These are:

  • Ground-level ozone.

  • Nitrogen dioxide.

  • Sulfur dioxide.

  • Carbon monoxide.

  • 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. The EPA also keeps track of lead levels, but these levels are not included in Air Quality Index (AQI) reports.

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. They are also eaten by animals and plants 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 AQI is a national index for five major air pollutants regulated by the Clean Air Act. These are:

  • Ground-level ozone.

  • Particle pollution (particulate matter).

  • Carbon monoxide.

  • 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. If you follow the index closely, you can see the healthiest time of day for your outdoor activities. Your local daily air quality report uses six color-coded levels. They include good, moderate, unhealthy, very unhealthy, and hazardous. Visit www.airnow.gov to find out the air quality where you live and to get tips on how to stay safe.

Online Medical Reviewer: Daphne Pierce-Smith RN MSN
Online Medical Reviewer: Robert Hurd MD
Date Last Reviewed: 8/1/2025
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