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Highway Study Sizes Up Pollution

Highway Traffic

In a study published in the November issue of Environmental Health Perspectives, EPA researchers have found for the first time that particle pollutants collected from the same airshed (the air within a particular geographic area) near a highway target either the lungs or heart depending on their size and associated chemical components.  The research improves understanding of the health impacts of air particles near roads.  

“Although many studies have reported diverse health effects with different particles from locations across the world, this is the first indication that particles of varying sizes taken from the same airshed may affect different organ systems,” says Ian Gilmour, an EPA Principal Investigator and senior author of the study.  “Researchers will apply the results to further investigate particulate matter’s (PM) health impact on the heart and lungs.”

More than 50 percent of the total emissions of PM in urban areas are related to road traffic.  Near roadway studies have reported associations between traffic density or proximity to roads and respiratory symptoms in children.

To learn more about the toxic effects of PM, EPA researchers took samples of three different sizes of the particles – coarse, fine, and ultrafine – near a highway in Raleigh, N.C.  Coarse particles (PM2.5-10) are produced by abrasion of automobile brakes and tires and dispersion of road dust, while fine particles (PM0.1-2.5) and ultrafine particles (PM0.1) are emitted from the tail pipe, or form as a result of atmospheric reactions.  Researchers then conducted toxicity studies in mice using samples of each particle.   

Researchers found the coarse PM produced significant lung effects while ultrafine PM (and to a lesser extent fine PM) induced heart effects. While samples were taken from two locations near the road (22 yards and 301 yards), for the health effects studied, there were no substantial differences in health effects between the two samples although the near road coarse material was enriched for several metal species.

The study is part of a larger research project being conducted by EPA’s Clean Air Research Program to better understand what type of air pollutants are common near roadways, how people are exposed to them, the extent of exposure, and the type and severity of health effects.

Citation: Cho, S.-H., Tong, H., McGee, J.K., Baldauf, R.W., Krantz, Q.T. & Gilmour, M.I. Comparative toxicity of size-fractionated airborne particulate matter collected at different distances from an urban highway. Environmental Health Perspectives, Vol. 117, No. 11, p 1682-1689. Nov. 2009. http://www.ehponline.org/members/2009/0900730/0900730.html.

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