Revised air quality index derived from an entropy function

• Main Authors: Yu-Chih Kuo, 郭育誌
• Other Authors: Wan-Li Cheng
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/47429152197232373109

碩士 === 東海大學 === 環境科學系 === 91 === Abstract The Environmental Protection Administration of Taiwan has been providing air quality service by the reporting of the Pollutants Standard Index (PSI). This standard was developed by US Environmental Protection Authority to estimate air quality by comparing concentrations of the main five common pollutants (PM10, SO2, CO, NO2, and O3). For each pollutant, a subindex was calculated from a segmented linear function that transforms ambient concentrations onto a scale extending from 0 to 500. The standard index based on the subindex with the highest. The main disadvantage of the PSI can only identify one pollutant at a time in the acceptable level. Hence, it cannot show if there is more than one pollutant that exceeds the standard level on the daily PSI. This study is based on the entropy function amending the current air quality index in order to create a Revised Air Quality Index (RAQI). By combining the RAQI and aggregation function, the current Pollutant Standards Index (PSI) is calculated by amending the index value and adding the index level. The greatest value of the sub index is the PSI value on the day. When the PSI value reaches 100, the region may be regarded as polluted. Therefore, this transformation could be misleading, and the confusion is further increased as the standard pollution concentration level varies among different countries. As a result, it shows that the distribution of index value of RAQI and current PSI are diverse, especially in the high pollution episode of the Kaoping Air Quality Region and Taichung Air Quality Region in the years 1999 and 2000. Also, the daily distribution of index value of RAQI and PSI are different. The RAQI value is more diffused and contains a larger area which conduces to show the air quality in a high pollution episode. From our research, air quality in the Kaoping Air Quality Region and the Taichung Air Quality Region are mainly affected by PM10 and O3, and air quality in the former region is more serious than in the latter. Information from five subindex pollutants (PM10, SO2, CO, NO2, and O3) and RAQI can present a local scale environment and offer the effective assessment. Keywords: Pollutants Standard Index (PSI), entropy function, Revised Air Quality Index (RAQI)