The Influence of a Noise Barrier and Vegetation on Air Quality near a Roadway

A growing number of epidemiological studies conducted throughout the world have identified an increase in occurrence of adverse health effects for populations residing, working, or attending school near major roadways. In addition, several air quality studies have identified increased concentration levels of certain pollutants near high traffic volume roads. The U.S. Environmental Protection Agency (EPA) has begun a research program investigating the relationship of traffic activity, environmental conditions, and near road air quality. As part of this program, the EPA is investigating the influence of noise barriers, vegetation, and other roadside structures on air pollutant concentrations near the road. This presentation integrates results from an air quality modeling assessment and air quality monitoring measurements to identify how noise barriers and vegetation near roads may impact local air quality. Air quality measurements were collected at sites with and without noise barriers and vegetation along a stretch of limited access highway in Raleigh, North Carolina, USA during the summer of 2006. This study allowed an assessment of the potential influence of these structures on near-road air quality. These structures influence pollutant transport and dispersion in the near-field (<300 m). Preliminary results suggest that, under some meteorological conditions, noise barriers and vegetation may reduce air pollutant concentration levels downwind of the barrier. These results may provide useful information in assessing the role of roadside structures on near road air quality for future land use decisions.