Elemental characterization of aerosols in urban and rural locations in Bangladesh

Abstract

Bangladesh became the first country in South Asia to ban the use of lead in gasoline in 1999. In 2003, two-stroke engine auto rickshaws were banned in the city centre of Dhaka, the capital of Bangladesh and one of the Asian mega-cities, in an attempt to improve the air quality. In July and August 2003, fine aerosol particles (PM2.5) were collected in Dhaka and in Rangpur in the northern part of the country. The aim was to study the effect of the action and to characterize PM2.5 particles in urban and rural areas of Bangladesh. Sampling was done with a cyclone of Dewell-Higgins type equipped with Teflon filters with a pore size of 3μm. Day- and night-time filters were collected in an attempt to understand the possible difference in air pollution between the two periods. An energy-dispersive x-ray fluorescence (EDXRF) spectrometer with three-axial geometry was utilized for the analysis of the elemental content of the particles. Large variations of concentrations for most elements in both Dhaka and in Rangpur were observed. Most of the elemental concentrations in Dhaka in daytime were higher than at night whereas the opposite was the case for Rangpur. The concentrations showed a significant influence of human activities and weather. Considerable concentrations of Pb were found despite the official ban of leaded gasoline. Motor transport, especially the two-stroke engine taxis and elements remobilized by burning, were the major sources identified. This is the first report on elemental concentrations in PM2.5 particles in both Dhaka and Rangpur. Copyright © 2005 John Wiley & Sons, Ltd.