Characteristics and health impacts of PM2.5-bound PCDD/Fs in three Asian countries

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were ubiquitous, persistent chemical compounds attached to particulate matter in the atmosphere. We aimed to study the characteristics of these pollutants in atmospheric PM2.5 of three Asian countries, including Taiwan (Taipei), Thailand (Chiang Mai), and Vietnam (Hanoi). We carried out a source apportionment analysis to determine significant PCDD/F contributors in these areas. Multiple media model was conducted to access the health impact assessment. The PM2.5 concentration in Taipei (n = 7), Chiang Mai (n = 20), and Hanoi (n = 10) were 18.4 +/- 6.21 mu g/m(3), 133 +/- 49.5 mu g/m(3), and 88.1 +/- 12.6 mu g/m(3), respectively. The PCDD/Fs level in Hanoi was 92.4 +/- 67.3 fg I-TEQ/m(3) and in Taipei and Chiang Mai was 5.01 +/- 2.39 fg I-TEQ/m(3) and 14.4 +/- 13.1 fg I-TEQ/m(3), respectively, which showed that the higher PM(2.5 )concentration was not necessary to follow with higher PCDD/Fs level. In all three cities, the effect of traffic on ambient PCDD/F level was significant (23-25 %). However, we also observed the specific sources of PCDD/Fs in each city during the sampling periods, namely long-range transport (Taipei, 55 %), Biomass/open burning (Chiang Mai, 77 %), and industrial activities (Hanoi, 34 %). In the carcinogenic risk estimation, the highest median total carcinogenic risk was in Hanoi (5.87 x 10(-6)), followed by Chiang Mai (1.06x10(-6)), and Taipei (2.95 x 10(-7)). Although diet was the major absorption pathway, the food contributor of exposure differed among the three areas due to the difference in food consumption composition.

Automated summary

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are commonly found in the atmospheric PM2.5 of Taiwan, Thailand, and Vietnam. However, higher PM2.5 concentrations do not necessarily translate to higher levels of PCDD/Fs. Traffic is a significant contributor to ambient PCDD/F levels in these cities, but specific sources vary between cities.