Effects of airborne pollutants on deterioriation and ageing behaviour of materials

Among natural atmospheric influences gasouse pollutants effect the deterioration of working materials and technical products. Recent calculations estimate the total costs of material damage caused by pollutants to several billion US Dollar annually in the Federal Republic of Germany. More precise caculations are not available because there is a lack of information about the contribution of airborne pollutants. In combination with humidity, temperature and solar radiation pollutants like SO2, NOx and O3 act onto surfaces of materials exposed to the atmophere, especially stone, glass, painting coatings and modern polymeric materials. This paper deals with the result of a study sponsored by the German "Federal Agency for the Environment" (Umweltbundesamt) reviewing nearly 1000 papers on this topic. In addition to this short overview the experimental weathering under laboratory conditions of some polymers will be described in detail: The test items are exposed in pollution chambers to chan ges in temperature, humidity, solar radiation with and without single and mixed pollutans. The used concentration (5000 myg/cubicmeter NOx and 2500 myg/cubicmeter O3) are one order of magnitude higher than measured in industrial areas. The duration of exposure will take more than two years. A projected network of free weathered test sites at different places in Germany will serve as a reference.