Washington, D.C. – Highway barriers erected to block traffic noise may also be reducing the amount of pollutants such as diesel soot reaching area residents, according to a new study by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA).

In a study, researchers released harmless “tracers”, gases that act as a stand-in for vehicle-related toxic pollutants, to follow their movement through the air. The study is the first to systematically and comprehensively investigate the role of atmospheric stability in real-world conditions on the movement of pollutants near highway barriers.

“While the barriers block the noise and view of hundreds of vehicles whizzing by, we found that they also reduce high concentrations of pollutants from those vehicles by lifting and channeling them away from the adjoining areas, often a residential area,” said lead author Dennis Finn. “We also found that the barriers tended to trap pollutants in the area of the roadway itself, especially at night in low wind speed conditions. The amount of pollutants was much higher on roadway areas flanked by barriers than in areas without them.”

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