Urban Grime Releases Trapped Toxins into the Atmosphere

posted: 08/18/15
by: Discovery.com Staff
Echangeur entre les autoroutes 110 & 105 à Los Angeles
Remi Jouan via Wikimedia Commons

The gunk and grime coating buildings, streets, cars and other outdoor urban surfaces reacts with sunlight to release nitrogen oxide into the atmosphere, according to new research from the American Chemical Society.

In urban areas, factories and automobiles spew large amounts of particulate matter into the atmosphere. The particles that stay airborne react with other pollutants to form ozone. However, the remaining highly nitrous particles form grime as they settle on outdoor surfaces.

Researchers had long believed that grime-trapped pollutants were neutralized. New research conducted in Germany, however, reveals that natural sunlight can trigger the release of those particles back into the air.

"The current understanding of urban air pollution does not include the recycling of nitrogen oxides and potentially other compounds from building surfaces," says James Donaldson, Ph.D. "But based on our field studies in a real-world environment, this is happening. We don't know yet to what extent this is occurring, but it may be quite a significant, and unaccounted for, contributor to air pollution in cities."

Donaldson's research was presented at a meeting of the American Chemical Society.

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