A study of air particulate pollution in Colombo using a nuclear-related analytical technique

Air particulate matter of two size fractions (coarse [2.5-10 microns] and fine [less than 2.5 microns]) were collected at an urban residential site (Colombo University ground) over a period of 12 mo during 1996 using a Gent PM10 stacked filter unit. Seventy-five sets of samples collected during this period were analyzed for 10 elements: Al, Si, K, S, Ca, Ti, Fe, Zn, Br, and Pb by energy-dispersive X-ray fluorescence, which is a multielement analysis. This is a highly sensitive technique enabling quantitative analysis of very low masses. The average concentrations of lead, sulfur, and bromine, which are generally associated with combustion products of automotive exhausts, dominate the fine fraction in this study. The minimum and maximum concentration of lead resulting in an annual average of 0.09 microgram/m3 was found to be 0.0042 and 0.441 microgram/m3 in particulate matter with less than 10 microns equivalent aerodynamic diameter. The maximum concentration determined is well below the limits set by the World Health Organization (0.5-1.0 microgram/m3). The recommended value for Pb in Sri Lanka is 0.5 microgram/m3. Al, Si, Ca, Ti, and Fe exhibited enhanced concentrations in the coarse fraction, which probably originate from disturbed soil as a result of wind and traffic.