The mural on the side of this building absorbs as much pollution as 780 trees!

Big cities don't just contribute to the pollution problem, the lack of trees and other greenery robs the landscape of its ability to heal itself. But scientists have found a way around this problem - photocatalytic paints. Located on a busy metro street in Warsaw, the mural on the side of this building was painted with photocatalytic paint dosed with titanium dioxide. Photocatalytic paints use light energy to neutralize pollution. Add a bit of titanium dioxide and the chemical reaction is even stronger. The reaction between the paint and pollutants converts Nitrogen Oxides and other harmful airborne pollutants into harmless nitrates. The paint is called KNOxOUT (nitrogen oxide, NOx - get it?) and it absorbs the nitrogen oxides created by cars, factories, and power stations. Sunlight acts