SIZE DISTRIBUTION OF ATMOSPHERIC AEROSOLS AND THEIR SOURCE IDENTIFICATION USING FACTOR-ANALYSIS IN BOMBAY, INDIA

In situ measurements of mass concentration of size-distributed aerosols were made using a quartz crystal microbalance cascade impactor. Aerosol samples were also collected by the conventional high-volume sampler for comparison and analysed for size distribution using a centrifugal analyser system and an image analyser system. The number concentrations were calculated for different sizes and these were subjected to factor analysis which gave four factors representing various source types of particulates. A power-function fit was applied to the size-distribution curves for the four size ranges grouped by factor analysis. Generally, size-distribution ranges are either selected according to the change of the slope of the curves or depending upon the measurement size ranges. The use of factor analysis makes the size-distribution groupings source dependent and also avoids the possible errors arising from averaging negative and Positive slopes.