ABSTRACT
Before 1980, the traditional method to make use of energy was the burning of coal directly. About 80% of fuel is used in this way in the whole country. A great number of industrial furnaces have rather short chimneys. The exhaust air is released into the ordinary air. Hence, ashes and substances that have not been burned completely spread in large measure into the living environment. Vast territories in north China have a long heating season of about 4 to 6 months per year. Small stoves are very common utensils for cooking and keeping warm in a household. When coal is burned in a stove, a great number of ash particles are exhausted with the gases. Among the exhaust gas, sulfur dioxide (SO
), carbon monoxide (CO), and other compounds are pollutants harmful to human health. The annual average concentration of total suspended particulate (TSP) in urban districts is 220 to 500 mg/m
and the annual average concentration of SO
is 70 to 150 mg/m
. Thus, the environment of the city is normally highly polluted. This is the so-called smoke-type pollution.
