Estimation of PM2.5 from MODIS Aerosol Optical Depth Over the Indian Subcontinent

Abstract

Daily estimation of ground-level PM2.5 (µg/m3) at high spatial resolution is a requisite for carrying out epidemiological studies with respect to air pollution. This can be made possible by exploiting the relationship between Aerosol Optical Depth and PM to provide high spatiotemporal predictions. We have used MODIS-derived Aerosol Optical Depth (AOD) measurement for the Indian subcontinent region in Mixed-Effect Model (MEM) to calibrate the AOD–PM relationship. Ground-level PM2.5 pollution data averaged daily were collected from 34 monitoring stations spread across the country. The MEM considers a fixed and random component, where the random components model the daily variations of the PM2.5–AOD relationship and also derives site-specific adjustment parameters. Comparison between the observed and predicted concentrations of the PM2.5 levels at the monitoring stations show R2 values ranging between 0.25 and 0.667 depending upon the effect of site bias on the PM2.5–AOD relationship.