China is a country with fairly rich energy resources. Coal is the dominant fuel in the cities and causes serious environmental pollution. In 1983, Tianjin used about 8,550,000 tons of coal. The total suspended particulate matter during the heating season was 0.72 mg/m3 in Tianjin urban area, over four times the maximum allowable concentration of 0.15 mg/m3 . One of the causes is the 1,060,000 small stoves burning coal for heating