Millennium Chemicals has developed a paint that absorbs nitrogen oxide (NOx) gases from vehicle exhausts, a pollution source that can cause smog and respiratory problems.
New Scientist magazine reports that the product is about to go on sale as Ecopaint, and is expected to effectively soak up NOx gases for five years.
The paint uses spherical nanoparticles of titanium dioxide and calcium carbonate mixed into a silicon-based polymer, polysiloxane. As the particles are only 30 nanometres across, the paint is clear and pigments can be added to give it colour. The porous polysiloxane lets the NOx gases diffuse through where they adhere to the titanium dioxide particles. UV radiation from sunlight converts NOx to nitric acid, which is then neutralised by the calcium carbonate.
The result is carbon dioxide, water and calcium nitrate that are harmlessly washed away. Trials of a similar coating in Milan reduced street levels amounts of NOx by 60 per cent and made it noticeably easier to breathe.