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Can Concrete Purify the Air?

Posted by John on August 9th, 2008

That’s the question on the minds of citizens in the Dutch town of Hengelo, where officials are paving a road with a special type of air purifying concrete to curb nitrogen oxide pollution from vehicle exhaust.

Engadget reports that the concrete bricks contain a titanium dioxide additive which, when exposed to sunlight, binds with nitrogen oxide particles and breaks them down into “harmless nitrates” that wash away with water.

Nitrogen oxide, or NOx, is produced by the burning of nitrogen-containing fuels like oil and coal. In the atmosphere, nitrogen oxide acts as a greenhouse gas and eventually turns into nitric acid, a component of acid rain. NOx also contributes to the formation of smog, which commonly exacerbates asthma and other respiratory conditions.

Officials are currently paving one section of a road to test out the air purifying concrete, which was developed at the University of Twente. They will take air samples and compare them with samples from another section of road paved with regular concrete.

I think that this air cleaning concrete could actually work, at least to some extent, since many air purifiers use titanium dioxide in conjunction with UV light. In the case of the so-called “green bricks,” the UV light comes from the sun.

But just how green are these bricks? Proponents say that the nitrates will wash away with rain water – but then what happens? They will eventually end up in streams, lakes, and drinking water. High levels of nitrates in drinking water may cause methemoglobinemia, a condition in which nitrates interefere with hemoglobin’s ability to carry oxygen through the blood. Infants are particularly susceptible to methemoglobinemia. While this condition is normally treated easily in humans, marine wildlife do not have the benefit of modern hospitals.

It seems to me like the air purifying concrete will simply convert one toxic atmospheric pollutant into a less toxic aquatic pollutant.

Even though researchers may not have fully considered the environmental impact of the nitrates, I think this is still a notable experiment because it may pave the way to other research that looks at building materials as air purifiers.

Wouldn’t it be great if we all had homes that absorbed air pollution instead of trapping it inside?

air purifiersUnfortunately, for now, the best way to avoid indoor air pollution is to run an air purifier.

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