Trend in Lead Content of Airborne Particles and Mass of PM10 in the Metropolitan Bangkok

Abstract

This research investigated lead in airborne particles smaller than or equal to ten micrometer (PM10) in diameter and mass of PM10 in the Bangkok Metropolitan Area. One hundred and thirty two samples were collected by standard high volume technique from the Bangkok Metropolitan Area during 1999-2000, filtered and measured for lead by flameless atomic absorption spectrophotometry. Concentration of lead in air particles (24 hr average) was 73.22 ng/m³ considerably less than the Thai ambient air quality standard value of 1500 ng/m³. Highest and lowest concentrations, 299.38 and 2.96 ng/m³ were found in Yoawarach road and Phahonyotin road, respectively. This and previous studies indicate a reduction in the concentration of lead in airborne particles since the 1991 campaign to use unleaded gasoline. The results of the study also showed a significant correlation between lead contents and mass of PM10. However, no correlation was observed between the concentration of lead in airborne particles and traffic density. This is probably due to the banning of leaded gasoline throughout the country since 1996 so that lead emissions and subsequent elimination of lead emissions via the exhaust system of vehicle is no longer an issue.