Material Damage Caused by Acidic Air Pollution in East Asia

Abstract

Atmospheric and laboratory corrosion tests were carried out to assess the intensity of air pollution in East Asia. Qualitative and quantitative atmospheric corrosion was estimated from the damage caused to bronze, copper, steel, marble, cedar, cypress and urushi (Japanese lacquer) plates, exposed to outdoor and indoor airs in some cities of East Asia. Brochantite and cuprite were formed on copper at sites where the sulfur dioxide concentrations were high, and basic cupric nitrate and cuprite at sites where nitrogen dioxide concentrations were high. Gypsum was formed on marble pieces exposed to indoor air at all sites but was not found on pieces exposed to outdoor air. Numerous fine spots (0.2–0.3 mm in diameter) were observed on surfaces of urushi plates exposed at foggy cities such as Chongqing, China and Taejon, Korea. The effects of atmospheric and meteorological factors on the damage to copper and marble plates in several cities in East Asia were estimated using regression analysis. The results indicate that sulfur dioxide is the most destructive of materials especially in China and South Korea. In Japan copper plates may be damaged under natural conditions and by sea salt. Copper may also be damaged by surface deposition of sulfur and chlorine. Marble may be substantially degraded by gaseous sulfur dioxide but sulfate ions in rain had no effect. The analysis of air pollution from the point of view of material damage was very useful in evaluating and visualizing the intensity of air pollution in East Asia.