A new study finds that highway barriers erected along roadways to block sound and sight of traffic for the adjoining neighborhoods may also be reducing the amount of pollutants, such as soot from diesel exhaust reaching area residents.

In this study conducted by NOAA and the U.S. Environmental Protection Agency, researchers released harmless “tracers” – gases that act as a stand-in for vehicle-related toxic pollutants such as carbon monoxide and heavy metals, and volatile organic compounds such as benzene. The basis of the study involved studying the movement of these tracers 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.

According to Dennis Finn, the study’s lead author, “While the barriers block the noise and view of hundreds of vehicles” driving by, it was “found that 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.”

A large body of research shows a variety of human health effects such as respiratory disease, cardiovascular illness, and cancer in individuals living or working near heavily trafficked roadways. It is difficult to measure accurately and isolate the effect of highway barriers on the transport and dispersion of the pollutants that cause these health effects in real-world environments with a wide range of atmospheric conditions.

The study can be found online and will appear in the January 2010 print edition of Atmospheric Environment.