The authors have engaged in the studies on the air pollution in Kawasaki City for the past thirty months.The following is the summary of the investigation.
1)In the south seaside industrial area of the city, there are power plants and many other factories.The most frequent wind direction in summer is S-SSW and that in winter is N-NNW.Thus, it is clear that in the summer dust and soot fall mostly in the urban area and that in winter, most of them are driven over the sea area.
2)There are remarkable regional differences in composition of deposited matter and these are chiefly due to the amount of insoluble substances, especially of ashes.
3)In industrial area, there is a tendency for deposited matter to decrease recently, but in other area the rate of deposition is not decrease: these results may be due to the fact that most collectors already installed are cyclone-type, which are insufficient for collecting fine particles in fly ash.It is therefore needed more collectors as high effic-iency as electric precipitator
4)At most places, significant correlations between deposited matter and wind direction were obtained, so that the contribution of the special source was estimated.
5)Rainfall is more closely correlated with soluble deposit and up to 46% of the dissolved matter is brought into the deposit gauges by rain.The insoluble matter is affected little by rain.
6)By studying the irregular month-to-month variations of deposited insoluble matter, coal burned, and most frequent wind direction, it was estimated that installation of dust collectors resulted in diminishing the amount of deposited matter.
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