Data mining to aid policy making in air pollution management

In the past two decades, the heavy environmental loading has led to the deterioration of air quality in Taiwan. The task of controlling and improving air quality has attracted a great deal of national attention. The Taiwanese government has since set up the National Air Quality Monitoring Network (TAQMN) to monitor nationwide air quality and adopted an array of measures to combat this problem. This study applies data mining to uncover the hidden knowledge of air pollution distribution in the voluminous data retrieved from monitoring stations in TAQMN. The mining process consists of data acquisition from Web sites of 71 data gathering stations nationwide, data pre-processing using multi-scale wavelet transforms, data pattern identification using cluster analysis, and final analysis in mapping the identified clusters to geographical locations. The application of multi-scale wavelet transforms contributes greatly in removing noises and identifying the trend of data. In addition, the proposed two-level self-organization map neural network demonstrates its ability in identifying clusters on the highdimensional wavelet-transformed space. The identified distribution of suspended particulate PM10 represents a complete, national picture of the present air quality situation, which contrasts the present pollution districts, and could serve as an important reference for government agencies in evaluating present and devising future air pollution policies. q 2004 Elsevier Ltd. All rights reserved.