Particulate Matter and Associated Heptachlor in the Indoor and Outdoor Air in Bangkok Homes and Vicinity

Abstract:

Eight homes in the Bangkok Metropolitan Region (BMR) were investigated to study the relationship between indoor and outdoor concentration of airborne suspended particulate matter (SPM) and associated organochlorine pesticides (OCP). Indoor and outdoor air was collected at three areas of BMR including urban, suburban, and rural during the dry season of 2007. Heptachlor was found at the highest levels among all analyzed OCP in the three sampling areas. Airborne samples were examined over 24-h for both gaseous and particulate matter phases, separately soxhlet extracted and analyzed by GC-ECD. The indoor heptachlor levels were the highest in urban homes (5.11 ng/m3) while the outdoor levels (3 ng/m3) were lower than indoor and not significantly different between the three sampling areas. For SPM, on average, the higher levels were observed outdoor than indoor for the urban area (i.e. 51 – 69 µg/m3 indoor vs. 69 – 95 µg/m3 outdoor) at urban homes. For rural homes, the outdoor levels were lower, 87 – 127 µg/m3, than the indoor level, 58 – 98 µg/m3. SPM were found high indoor in the suburban and rural homes with the mean indoor and outdoor air ratios (I/O ratios) larger than 1.0, suggest the predominant influences to high strength of indoor sources activities. Overall, SPM levels in this study were lower than those observed in other studies in Thailand. However, the high accumulations of these pollutants indoors are needed to concentrate for further human exposure study.

Keywords: SPM, Heptachlor, Indoor air, Outdoor air, I/O ratio, Bangkok