Effects of airborne pollutants on deterioration and aging behavior of materials

Among natural atmospheric influences, gaseous pollutants effect the deterioration of working materials and technical products. Recent calculations estimate the total cost of material damage caused by pollutants to be several billion dollars (US) annually in the Federal Republic of Germany. More precise calculations 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 sulfur oxide (SO sub 2), nitric oxide (NO sub x) and ozone (O sub 3) act onto surfaces of materials exposed to the atmosphere, especially stone, glass, paint coatings, and modern polymeric materials. This article deals with the results of a study sponsored by the German, Federal Agency for the Environment (Umweltbundesamt). The experimental weathering of some polymers under laboratory conditions will be described in detail. The test items are exposed in pollution chambers to changes in temperatur e, humidity, solar radiation with and without single and mixed pollutants. The concentrations used (5000 myg/cbm SO2, 5000 myg/cbm NOX, 2500 myg/cbm O3), were one order of magnitude higher than those measured in industrial areas. The duration of exposure was more than 2 years. A projected network of free weathered test siets at different places in Germany served as a reference.