Atmospheric PCDDs/PCDFs levels and occurrences in Southeast Asia: A review

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are toxic compounds derived from anthropogenic sources that stay in the environment for long periods. Ambient air has become the most important pathway for the transfer of PCDDs/PCDFs from emission sources to the environment. This review intends to summarise the information available on atmospheric PCDDs/PCDFs in the countries of Southeast Asia to provide a detailed description of the trends in PCDDs/PCDFs emissions, key sources, and levels in urban, rural, and industrial air as reported in peer-reviewed literature since 2000 and by the United Nations Environment Programme. As the largest country in Southeast Asia, Indonesia is the major PCDDs/PCDFs emitter, accounting for 72.81% of the total release of PCDDs/PCDFs in the air from all available inventories in this region, while Brunei Darussalam is the lowest emitter, contributing to less than 0.02%. Open burning processes have become the largest source of ambient PCDDs/PCDFs in the region (69.62%), followed by waste incineration (10.69%), and ferrous and non-ferrous metal production (8.78%). PCDDs/PCDFs levels in rural areas ranged between 10 and 38 fg TEQ m^-3; however, where open burning waste has occurred, the levels rose to 12-29 times higher. In urban areas, ambient levels were 15 times greater than in rural areas, varying from 23 to 565 fg TEQ m^-3. Atmospheric concentrations near industrial palm oil and waste incinerator sites were between 64 and 1530 fg TEQ m^-3. The non-cancer risk of ambient exposure to PCDDs/PCDFs through inhalation is low among populations near facilities emitting PCDDs/PCDFs. The lack of local technical capacity, the high economic costs, and the lack of established human resource capacities have been the major challenges in conducting ambient PCDDs/PCDFs studies in most countries in the region.