The analyses of ozone in Chiayi

According to the statistics by the Environment Protection Administration (EPA) in recent years, the frequency of PSI(Pollution Standard Index) >100 in Chiayi, Yunlin and Tainan area have already exceeds the frequency in Taichung area. The Chiayi, Yunlin and Tainan area becomes to one of the seriously polluted area, which is merely better than Kaohsiung and Pingtung area.
The Chiayi area is an agricultural county, the regional industry is mainly the manufacturing of civil articles. However, the frequency of high ozone episodes is getting higher in recent years. Consequently, this study focused on the air quality in Chiayi area.
In this study, we collected the databases from EPA, which is from 1995 to 2007 and analyzed the variation trend of air quality. We also analyzed the wind direction to comprehend the source of air pollutants. In order to comprehend the forming reasons in Chiayi area, we also used the back trajectory model to analyze the ozone episodes in 2001, 2002 and 2003.
The result revealed that, the air quality in Chiayi area became worse obviously after 2002. According to the analysis of wind direction, the ozone episodes mainly occurred in north wind condition. The back trajectory analysis reveled that, the trajectory lines passed through sixth Naphtha cracking plants increased obviously. However, the trajectory lines passed through the Taichung industry area were almost changeless. Thus, we concluded that the sixth Naphtha cracking plants has to do with the worsen of the air quality in Chiayi area.