A SURVEY OF AIR-QUALITY IN SINGAPORE

Ambient aerosol samples were collected near an industrial area in Singapore during the period of July 91 to January 92. The sampling site was a highway at a height of about 20 m. PIXE analysis of these samples was carried out using 1.8 MeV protons. Thirteen trace elements were observed, ranging from Si to Pb. Among these, Cl and S had the highest concentrations. The former was attributed to the sea-salt particles and the latter could be due to the presence of oil refineries in the vicinity. Pb was found to be below the detection limit of 30 ng m-3 in most of the samples analysed. This is likely due to the fact that unleaded petrol was used by many cars in Singapore and that the sampling point was quite a distance away from the ground level. The observed variations in concentration for most of the trace elements were well-correlated with traffic intensity and meteorological conditions. Time variation patterns on weekdays and during weekends were also observed. A higher level of pollutants was detected during the period when there were prolonged forest fires in the nearby islands in Indonesia.