We have produced various excretions and wastes as a result of a production activity or consumption activities. ¡¡When there was less quantity of waste, it was fully processed by the natural purification action. But when the excretions became abundant and surpassed the amount that mother nature could hold, then the exceeded waste materials which cannot depend for processed by natural purification has been produced. In this way, Contamination of natural environment got worse and the ecosystem was disturbed. Damage arose to man's health.
             The industrial pollution type measure towards air pollution centering on SOx accomplished steady progress. From the second half of the 1970s, the air pollution in a big city area poses a problem, however the serious situation continues. The sources of air pollution are the exhaust gas from a factory, and the car increases every year. The measure against a nitrogen oxide (NOx) and floating particle-like substance (SPM) discharged from a diesel car has been important pollutant. These are needed that not only implementation of much more measure toward air pollution, but also our understanding and cooperation for implementation of the measure to air pollution. Moreover, global environment problems, such as global warming, are becoming so serious threat. Air pollution is also one of the causes to global warming.
             Japan accomplished remarkable economic development after World War II. Air pollution became big social consequences of the development. The Japanese government adopted measure, such as establishment of ¡∘Clean Air Act (1968)¡», setting up of air environmental quality (1969 aging one by one), discharge regulation of an air pollution substance, implementation of nationwide air pollution monitoring. As a result, the air pollution by SOx or carbon monoxide (CO) has improved sharply. But because of the increase in traffic in recent years, the contamination by nitrogen oxide (NOx) and
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