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Respiratory Health & Air Pollution

This website is archived for historical purposes and is no longer being maintained or updated.

The Healthy Community Design Initiative, also known as the Built Environment and Health Initiative, is no longer a funded program and the information on this website is not being reviewed and updated on a regular basis.


smoggy city

Transportation-related pollutants are one of the largest contributors to unhealthy air quality. Exposure to traffic emissions has been linked to many adverse health effects including: Exacerbation of asthma symptoms, diminished lung function, adverse birth outcomes, and childhood cancer.

Common transportation-related air pollutants include carbon monoxide, nitrogen dioxide, and particulate matter. Ozone, formed when nitrogen dioxide and sunlight react, is also a common pollutant. Particulate matter and ozone are known respiratory irritants that can aggravate asthma either by themselves or when combined with other environmental factors. Recent health studies also suggest that particulate matter is a risk factor for cardiovascular disease.

Motor vehicles contribute to more than 50% of air pollution in urban areas. The design of communities and transportation systems impacts how often automobiles are used, how many automobile trips are taken, and how long those trips are. Reducing automobile trips by increasing mass transit use, carpooling, walking, and bicycling can help reduce air pollution, especially in urban areas.

Several years ago, researchers took advantage of a natural experiment to learn about the impact on pediatric asthma of decreased traffic levels and improved air quality. During the 1996 Summer Olympics Games in Atlanta, when peak morning traffic decreased 23% and peak ozone levels decreased 28%, emergency visits for asthma events in children decreased 42%. At the same time, children’s emergency room visits for causes other than asthma did not change. These results suggest that efforts to reduce traffic congestion and improve air quality can also help improve the respiratory health of a community.

For more information on respiratory health & air pollution, refer to the following resources:

National Center for Environmental Health – Air Pollution and Respiratory Health
The Air Pollution and Respiratory Health Branch of the National Center for Environmental Health directs the Centers for Disease Control and Prevention’s fight against respiratory illness associated with air pollution.

Additional information on respiratory health & air pollution and related topics can be found in the Additional Resources section.


Friedman MS, Powell KE, Hutwagner L, et al. Impact of changes in transportation and commuting behaviors during the 1996 Summer Olympic games in Atlanta on air quality and childhood asthma. JAMA 2001;285:897-905.

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