An investigation of air pollution in southern Ontario, Canada, with MODIS and MISR Aerosol Data

On October 3-5, 2005 a smog advisory was issued for southern Ontario,Canada, due to high ground-level ozone and fine particulate matter (particles less than 2.5 microns in diameter - PM 2.5). Warm temperatures up to 28 C, high humidity and gentle winds contributed to a build-up of pollutants locally. In addition, southerly winds transported pollutants from the neighbouring United States northward into Canada. Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) were obtained for four days - October 1st, 3rd, 4th, and 5th, 2005. The transport of high aerosol loadings northward across the Great Lakes is clearly evident on the images. We used linear regression analysis to investigate the relationship between MODIS aerosol optical depth (AOD) and ground-level PM2.5 during this period. The results suggest that a strong relationship is derived when meteorological variables are included in the regression model. An R2 value of 0.76 was obtained with MODIS AOD, average temperature, wind speed and relative humidity variables included as predictors of PM2.5.