Air quality monitoring using remote sensing and GIS technologies

Air quality monitoring is needed to control air pollution in urban areas. A limited number of air quality monitoring stations limits the initial strategy of pollution prevention program in Malaysia especially at micro-scale level. Existing technique used to monitor air quality involves manually measured pollution concentrations within the area of measuring station. New technique which integrates satellite remote sensing and Geographical Information System (GIS) by the authors can be used to continually monitor air quality at micro-scale level. Images from Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and eight (8) Continuous Air Quality Monitoring Stations (CAQM) data are used to determine the relationship between digital number (DN) of the thermal infrared band and the two (2) air pollutant parameters, i.e. Carbon Monoxide (CO) and Particulate Maters (particle less than 10 microns in size - PM10). A number of models have been developed by the authors to relate the DN of Landsat 7 ETM+ and the air pollutant parameters. Since there are limited numbers of CAQM stations available, the concept of “virtual stations” is introduced to densify CAQM stations. Based on these stations, kriging interpolation method (available in GIS software) is used to generate the air quality maps of the study area. The advantage of this method is it allows a more detailed assessment of air quality within urban areas with limited CAQM stations. Maps of pollution concentration generated from virtual stations using kriging interpolation method produce a more realistic distribution of air pollution. The concentration of CO and PM10 are highest in the industrial zones of the study area (Shah Alam). This method can be used by environmental managers and local authorities to continually monitor air quality in urban areas.