Air-Purifying Road Surface Eats 45% of NOx Pollution

concrete road photo

Photo: Flickr, CC


Researchers at the Eindhoven University of Technology in the Netherlands have tested pollution-eating concrete on about 1,000 square meters of roads in the town of Hengelo. We already knew it worked in the lab, but this was a real-world test and the results are pretty impressive: a 25 to 45% reduction in oxides of nitrogen (NOx) over the special roads. This could mean that someday our roads and other concrete structures could be used to clean up the air. How does it work? Read on for the details.

concrete road photo

Photo: Flickr, CC

How Does Air-Purifying Concrete Works

"Vehicle exhaust gases contain nitrogen oxides (NOx), which cause acid rain and smog. The air‑purifying concrete contains titanium dioxide, a photocatalytic material that removes the nitrogen oxides from the air and converts them with the aid of sunlight into harmless nitrate. The nitrate is then rinsed away by rain. These stones also have another advantage: they break down algae and dirt, so that they always stay clean." (source)

Titanium dioxide is the naturally occurring oxide of titanium (TiO2) and it's used in white paint, sunscreen, food coloring, etc. As for the nitrates, NOx would naturally break down that way, so it shouldn't add to the problem. In fact, it might make it easier to capture them and mitigate the problem.

This material can also be mixed with regular asphalt for use where you don't want or need a concrete road. It's pretty versatile.

Dealing with Symptoms

Of course, it's much better to attack pollution at the source instead of just putting a band-aid over the symptoms, but the reality is that it will take a while to clean up all NOx sources, and in the meantime, people's lungs could benefit from this kind of technology. Call it a second line of defense.

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Via Science Daily
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