Assessment of the effect of air pollution on material damages in Northeast Asia

Material exposure tests have been carried out to evaluate the relationship between air pollution and material damage, with the cooperation of researchers in Japan, China and Korea, since 1993. Test materials such as bronze, copper, marble, and steel have been exposed to both unsheltered and rain-sheltered outdoor conditions, with the simultaneous passive sampler measurement of SO2 and NO2 concentrations, at 17 separate sampling sites in East Asia. Meteorological data were gathered from the AWS in each country, and the chemical compositions of wet deposition analyzed by bulk sampling of the monthly rainfall. As a result, the corrosion rates of the test materials in ambient air were found to be in the order: carbon steel >marble >bronze copper. The corrosion rates of test materials in the unsheltered outdoor conditions were 2.28–6.24 times larger than those under the rain-sheltered conditions. The rates of corrosion were also found to be the highest in the heavily polluted areas of China, with these rates for the metal pieces generally being proportional to the SO2 concentration. With the two Korean sites, the test pieces at the Daegu site displayed higher rates of corrosion, possibly due to the higher SO2 concentration.