Highway barriers erected along roadways can be perceived as massive monuments to the future and were intended to block the sound and sight of traffic for the adjacent neighborhoods. They may do a bit more in terms of air borne pollution.

In a study by NOAA and the US Environmental Protection Agency, researchers released harmless “tracers” to measure the potential movement of pollutants such as carbon monoxide and heavy metals, and volatile organic compounds such as benzene. The results showed a significant reduction for those neighborhoods in pollutants as a result of the barriers.