This study was based on two-year MODIS aerosol optical depth(AOD)product and PM10 mass concentrations calculated from Air Pollutant Index(API)in Beijing and the hourly averaged measurements at Peking University in Beijing and Yuen Long station in Hong Kong.The direct correlation between AOD and PM10 mass concentration was found relatively low.The correlation coefficient between aerosol surface extinction(achieved from dividing AOD by seasonal aerosol scalar heights)and PM10 mass concentration increased to s...