Two years of aerosol pollution monitoring in Singapore. a review

An aerosol sampling campaign was initiated more than two years ago in Singapore. The aim was to determine the average elemental concentrations in fine and coarse aerosol fractions as well as to identify major pollution sources and their impact. For that purpose, two air samplers were employed at two different sampling locations; one sampler was a fine particulate aerosol sampler (PM2.5) located at the vicinity of a major industrial area. The other was a stacked filter unit (SFU) sampler designed for collection of fine and coarse fractions (PM2.5 and PM10) and installed in the residential area. Samples were taken typically twice a week and in several occasions daily. During the period of two years more than 700 aerosol samples were collected and analyzed using PIXE and RES techniques. All samples were analyzed for is elements ranging between Na, Mg, Al, etc. up to As and Pb. Large daily and seasonal variations were found for most of the elements. These variations are attributed mainly to meteorological changes, in particular changes in wind speed and direction. On several occasions, short term sampling was performed to identify fingerprints of major pollution sources such as road traffic, refineries, as well as the rain-forest fires in neighboring countries. A summary of our findings is presented and discussed. (C) 1999 Elsevier Science B.V. All rights reserved.