Samples of the surface of anti-noise barriers, which had served for two years as test surfaces for the multifunctional Protectam FN® coating, were taken for laboratory measurements of their effectiveness in cleaning the air of exhaust gas emissions from automobile traffic.
Dangerous oxides of nitrogen (NOx) are among the most closely studied of emissions. Workers from the J. Heyrovský Institute of Physical Chemistry in Prague performed certain measurements of effectiveness according to modified ISO norms and proposed norms of the European Committee for Standardization (CEN). The results of the tests showed that even two years after they were applied to the surface of walls, FN® photocatalytic coatings maintained exceptionally high effectivity, which was practically the same as that of newly applied layers of coating. Tests showed that their effectiveness in removing NOx reached 40% when a volume of air made a single contact with a treated surface on a test wall activated by UV light.
The test wall was placed in the proximity of a high-traffic road along which about 30,000 cars pass every day. At concentrations of 30-40 µg of NOx emissions per cubic meter of air where the wall was located, 300 square meters of surface coated with FN® coating were able to clean the air of 140 kilograms of nitrogen oxides in two years. About the same amount of nitrogen oxides is produced by one automobile with a two-liter diesel engine in 1.5 million kilometers of travel. Assuming 35 µg of pollutants per cubic meter of air, this means cleaning a volume of 2 billion cubic meters of air every year! For comparison, that is the volume of air breathed in and out by 235 people in an entire year!
The anti-noise barrier tested in the Barrandov distict of Prague is not the only giant ecological air cleaner in the city. A similar concentration of atmospheric pollutants is found on Pod Kaštany Street in the Prague 6 district. The facades of two buildings in the Villa Bianca apartment complex are protected by FN® coatings from deposits of grime precipitated from the air. The overall area of these self-cleaning facades is 850 square meters.
These facades also function like air cleaners. They remove up to 198 kilograms of NOx from the air in one year. This represents an enormous amount—5.7 billion cubic meters—of cleaned air.
Prague has even more houses like this with facades that are treated with FN® coating and that also function like efficient, ecological air cleaners.