MONITORING LEAD IN SUSPENDED AIR PARTICULATE MATTER IN HO-CHI-MINH-CITY

Airborne lead has been measured in Ho Chi Minh City in the framework o f an environmental monitoring programme since late 1992. Air particula te matter was collected atop an eight-storey building in working hours in a near-downtown residential area. The average concentrations of le ad and total suspended particulate matter (TSP) for the 1993-1994 peri od were (179 +/- 12) and (90 +/- 6) mu g m(-3), respectively. Autoexha ust is believed to be a major source of lead; however, refuse burning and firecracker discharges may also contribute to some extent. Lead, w hile decreasing in rainy season, exhibited a rather irregular seasonal pattern resulting in a poor anticorrelation with rainfall in contrast with TSP. Lead values from similar to 60 to 240 ng m(-3) covering ove r 60% of measured data fit very well with a lognormal distribution mod e which reflects the lognormality of wind speed with almost the same a tmospheric stability condition. The deviations from this main distribu tion mode of lead concentrations outside this range are interpreted as due to the changes in atmospheric stability conditions that occurred during seasonal transition periods as well as under prolonged cyclonic and anticyclonic conditions. Copyright (C) 1997 Elsevier Science Ltd.