Road coating against air pollution?!

Roads are often seen as symbols for air pollution, because in the end they play a key role in the polluting transport sector. However, a pilot project from Hesse now shows that even the road surface can contribute to mitigating the pollutant - under the right conditions. In cooperation with the mobility service provider Hessen Mobil, the city of Alsfeld decided to renovate a very busy stretch of road with a new road surface that, thanks to its special chemical composition, can lead to a considerable reduction in nitrogen oxide levels.  

This involves an area of about 7000 square metres on the 750-metre section of the Schellengasse. A street about which environmental associations had repeatedly complained because the pollutant values in the air, especially nitrogen oxide (NO2), were constantly above the limit value - and thus endangered not only the environment but also the health of the residents. It is precisely to this problem that the new granulate is supposed to provide at least a partial solution. With the help of the special coating, which consists of a stable concrete mixture with added titanium dioxide, it was possible to reduce NO2 by 11.6 micrograms per cubic metre of air. This corresponds to an impressive reduction of 27.5 percent of nitrogen oxide - explains FCN Nüdling from Fulda, the company responsible for the concrete.  

The key to the success of the new asphalt lies in the addition of titanium oxide, which "acts as a catalyst, allowing sunlight to break down pollutant particles. This does not combine with nitrogen oxides, which are emitted by passing car exhausts, for example, and is therefore not consumed. In this way, nitrogen can be broken down and converted to nitrate, which remains on the road surface until the next rainfall - without entering the atmosphere.  

"A good result" for the development of more sustainable road construction - says Günter Herles of Hessen Mobil - with considerable potential for application in other road resurfacing projects as well. Not only in Hesse, but throughout Germany. After all, existing and upcoming internal combustion engine driving bans could only benefit from the use of such a method on numerous roads in the state. It would also make it easier to comply with the limit values for air pollutants required by the European Union. In short, an effective supplement to effective but often insufficient traffic measures on their own. The new asphalt would in fact be able to reduce emissions that are harmful to the climate and to health, where peak NO2 levels could occur despite driving bans or environmental zones.  

But it could be a long time before such use becomes possible on a large scale. Since only one company currently offers the road construction material. For a large-scale rehabilitation of the road infrastructure, the current availability would be far insufficient and at the same time too big a challenge for a single company. There is still hope for the implementation of this or similar innovations. To make transport greener and more environmentally friendly, not only in terms of vehicles, but also on the roads they travel on.