Analysis of cardinal grey relational grade and grey entropy on achievement of air pollution reduction by evaluating air quality trend in Japan

The Japanese government has promoted a number of policies regarding air pollution control to regulate the maximum permissible limits of air pollution, including motor vehicles, industrial activities, and firecrackers exhausts, which can be established as a mechanism for monitoring air pollution. Studies of Japan's air pollution have been presented since the 1970's, but only few studies have focused on evaluating air quality trend by grey system, which can be used to calculate the grade of air quality. The study used cardinal grey relational grade and grey entropy to calculate the data of five major Japan's air pollution such as sulfur dioxide (SO2) carbon monoxide (CO), suspended particulate matter (SPM), Nitrogen dioxide (NO2), and photochemical oxidants (OX) from 2002 to 2011 for evaluating the air quality trend in Japan. The relation between achievement of air pollution elimination and outcome of air pollution reduction can be determined via evaluating air quality trend. The results of this study can demonstrate the trend of air pollution spread from 2002 to 2011 and also can be used to establish a permissible limit for each type of air pollution. Furthermore, this study can be a reference for further studies on evaluating air quality trend and also on air pollution control and environmental protection, as an ultimate goal. [Display omitted] •Because economy progress around the world, many environmental pollution occurred.•Most countries conduct many researches to alleviate the environmental pollution.•Air pollution reduction can be evaluated via analyzing air quality trend.•This study aims to evaluate air quality trend of Japan by grey relational grade