Abstract This project began from April 13, 2005, and finished at the end of December of 2005. During this period, the project had finished: (1) Basic data collection, (2) Long-term air quality trend analysis of Taiwan area, (3) Editing the annual report of air quality maintaining strategy of year 2004, (4) Air quality time and space trend analysis, (5) Major air quality episode analysis, (6) Editing the related reports of research projects of the Department of air quality and noise control of 2004. 1. Basic data collection: The project had finished the editing of air quality data of 2004, and the statistical analysis of PSI values. The quality assurance and quality control of air quality monitoring data were presented in the project. Air qualities in major cities of world were discussed also. 2. Long-term air quality trend analysis of Taiwan area: The project had finished the long-term trend analysis from 1994 to 2004 of five mayor air pollutants, including the long-term trend and seasonal variation. 3. Editing the annual report of air quality maintaining strategy of year 2004: The draft report was submitted to EPA in the middle of August, and the finial report was submitted at the end of September after the review and revise of EPA. The major contains include current air quality, current concentrations of major air pollutants, relative regulations and strategies. 4. Time and space trend analysis of air quality: The project had finished the long-term trend analysis of the air quality pollutants standard index (PSI). The space trend analysis of O3 and PM10 were presented also. From the concentration variation of PM10 in Taiwan area, the results showed the concentration had close relation with seasonal variation and population densities. Higher concentration mostly occurred in the spring and winter. In the seven air quality basins, higher concentrations occurred in the Central, Yun-Chi-Nan, and Kao-Ping air quality basins, while lower concentrations occurred in the Hwa-Tung and I-Lan air quality basins. The O3 concentration variations were related to seasonal characteristics, monsoon wind, local topographies and population densities. From the equal concentration contour lines, ozone concentrations showed more regional diversities than PM10. In Taipei area, higher ozone concentrations occurred in spring and summer, and lower ozone concentrations occurred in winter. But in Kaohsiung area, higher ozone concentrations occurred in autumn, and lower ozone concentrations occurred in summer. In Hwa-Tung area, higher ozone concentrations occurred in spring and autumn, and lower ozone concentrations occurred in summer. 5. Major air quality episode analysis: From the results of PM10 episode analysis, high PM10 concentrations occurred in spring and winter in Taiwan area. Especially in Central air quality basin, high PM10 concentrations appeared from winter to spring due to the variations of seasonal wind directions in Chushan area, which was the reason why the PM10 concentrations always higher than other area. In Nantou County, high PM10 concentrations came from the Northern-Eastern wind in the winter, and the river stone mining. From the results of O3 episode analysis, high O3 concentrations occurred in spring and summer in Northern and Chu-Miao air quality basins. In Central and Yun-Chi-Nan air quality basins, high O3 concentrations occurred in summer, autumn and winter. In Kaoping air quality basin, there were high O3 concentrations occurring every months during the year. High O3 concentrations occurred in autumn in Hwa-Tung air quality basins, without any episode day. 6. Editing related the reports of research projects of the Department of air quality and noise control of 2004: Major editing projects included general affairs projects, stationary source projects, movable source projects and international environmental pollution topics etc., and the executing reports, abstracts, and their contributions to EPA’s air pollution control policies and strategies.

Air Quality