NOx is a pollutant that comes from all combustion emissions. It can be minimized but not eliminated at the stack. Painted surfaces (a very common urban surface area) with photo-catalytic characteristics may be able to clean the air of nitrogen oxides and other health-endangering substances. Using a new testing procedure, Fraunhofer researchers can find out how the coatings behave during a long-term test. They will introduce the new test at the booth of the Fraunhofer Building Innovation Alliance January, 2013, in Munich, Germany.