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New Study finds City Grime is Adding to Air Pollution

August 20, 2015
Environmental Protection

The ‘black grime’ that coats many city buildings may be adding to poor air quality according to a new study presented at the 250th National Meeting & Exposition of the American Chemical Society (ACS).

Canadian scientists from the University of Toronto, believe that the effect of sunlight on grime encrusted buildings leads to the release of both nitrogen dioxide and nitrous acid (HONO), which is a key driver in the formation of photochemical smog. The presence of HONO is considered to be significant, as it is difficult to directly measure the amount of the compound in the atmosphere. Scientists looked at conditions over a six week period in Liepzig and during a yearlong study in Toronto using glass beads and found that the action of sunlight reduced levels of nitrate by 10%, compared to samples that were in the shade.

Professor James Donaldson, who led the research team, believes the findings will help build a clearer picture of how smog forms in cities. “If our suspicions are correct, it means that the current understanding of urban air pollution is missing a big chunk of information,” He said. “In our work, we are showing that there is the potential for significant recycling of nitrogen oxides into the atmosphere from grime, which could give rise to greater ozone creation.”

You can view a full briefing on the study HERE