Air pollution is substances in the air — either man-made or natural — that can harm human health and the environment. Fine particles from burning coal, fossil fuels, and wood can get deep into our lungs and spread to blood vessels throughout the body.

A 2013 report from the World Health Organization (WHO) stated that outdoor air pollution is a major risk to human health. They reported that air pollutants could aggravate asthma, increase coughing, and decrease lung function. It could also increase the risk of bronchitis, headaches, irregular heartbeat, nonfatal heart attacks, and premature death in people with heart or lung diseases.

Major contributors to air pollution in cities include exhaust from cars, buses, and airplanes. Ground-level ozone, which results from engine and fuel gases interacting with the sun's rays, is also a factor.

Acid rain forms when moisture in the air interacts with nitrogen oxide and sulfur dioxide released by motor vehicles and factories and power plants that burn coal or oil.

However, rural areas aren't immune to air pollution. Dust from tractors plowing fields, trucks and cars driving on dirt or gravel roads, rock quarries, and smoke from crop fires and wood burning can all pollute clean air.

Though everyone is affected by air pollution, populations that are particularly at risk include:

  • people with asthma
  • people with heart disease
  • people with respiratory diseases
  • children
  • active adults who exercise outdoors
  • older adults
  • people with diabetes
  • pregnant women

The U.S. Environmental Protection Agency (EPA) uses the Air Quality Index (AQI) to provide the public with an easy way to understand the local air quality on any day. The AQI assigns the air quality a score from 0 to 300.

The higher the AQI value, the greater the health concerns. When AQI levels reach above 100, air quality is unhealthy. You can track the AQI for your area in your local newspaper, on television or radio weathercasts, and online.

When levels reach 101 to 150, at-risk groups should reduce time spent outdoors and prolonged or heavy outdoor exertion, as exercise increases air intake. When the AQI reaches unhealthy levels of 151 to 200, everyone should limit exposure.

When levels reach 201 to 300, it is considered unhealthy for sensitive groups — especially those with heart disease. People at risk should avoid all outdoor activity.

Air pollution is highest during the heat of the day, so plan your outdoor activities for early morning or late evening. Avoid walking or biking on busy streets. If you're sitting in traffic, use the recycled air setting on your air conditioner to help cut down on fumes.

If you're in a location where you can't escape the pollution, try putting a handkerchief over your mouth and nose to help filter gas and smoke.

Antioxidant-rich foods like fruits and vegetables can also help shield your body from the damaging effects of free radicals created by air pollution.

Finally, don't forget that indoor spaces can be polluted, too. To limit pollution in the home, follow these recommendations:

  • Consider purchasing an indoor air purifier.
  • Avoid air fresheners and candles.
  • Keep filters on air conditioners and heaters clean.
  • Vacuum often.
  • Wash sheets and stuffed toys to get rid of dust mites.
  • Wash mold and mildew off hard surfaces.
  • Open the windows to circulate the air on days when the air quality is good.

With a little extra effort, you and your family can breathe cleaner air and enjoy better health.