Can dirty buildings increase air pollution?

In our cities and towns, dirty, shabby buildings are common. Did you know, however, that dirt that has accumulated over time emits ozone (the harmful substance in smog) when it is exposed to sunlight? Smog can be extremely dangerous to the public’s health. A new study has changed the way we view dirty buildings in cities. It would appear that dirty buildings are not just an eyesore but could also contribute to air pollution.

Dirt and grime can accumulate on buildings in urban areas due to the thousands of particles that are present in the air. The dirt on buildings can be made up of a variety of substances. Most of them are derived from factory emissions, car exhausts and other human-made activities. Improve the air inside your property with Air con Gloucester. Find out more at

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Nitrogen oxide is one of these substances. When exposed to sunlight, it splits to produce nitric dioxide and an oxygen atom. This oxygen atom is then assimilated into the air and forms ozone.

The stratosphere is where ozone exists naturally. The process that creates it is when ultraviolet radiation breaks down oxygen molecules. It is the most important protective layer that protects life on Earth from harmful UV radiation. On the ground, however, things are different. As the main component of smog, a mixture of ozone and nitrogen oxides, sulphur, carbon monoxide and other pollutants, ozone is a harmful pollutant.

There was a belief that the particles found in grime on building surfaces were stable and didn’t contribute to air pollution. A chemistry professor at the University of Toronto conducted tests which suggest that this may not be the case.

The dirt was collected in Toronto and Leipzig, Germany. The glass beads collected the dirt because they had a larger surface area than a flat window. Some of the grime was exposed to sunlight while others were left in shade. Both sets of beads released nitrogen oxides in the air, but those that were left out in the sun emitted 10% extra. It’s probably time to remove some grime that sits on urban buildings.

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Results suggest that dirt on buildings in urban areas could contribute to air pollution. Previous methods of combating and reducing poor air quality were missing an important chunk of the pollution’s source. It is reasonable to assume that dirt on buildings could be recirculating nitrogen oxides back into the atmosphere, causing a higher rate of ozone formation at ground level.

Author: Niru Taylor

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