Concurrent study of long-range transport of fine and ultrafine particles from peatland fires in lower Southeast Asia

The physical and chemical characteristics of atmospheric fine (PM₁ and PM_2.5) and ultrafine particles (PM_0.1), during peatland fires in Indonesia and transported over a long distance to southern Thailand, were investigated to add more insight into the impact in lower Southeast Asia region. The background PM concentrations in Pekanbaru, Indonesia were approximately 1.5–3 times as high as those in Hat Yai, southern Thailand. The PM and PM-bound PAH mass concentrations in Hat Yai during the haze event were significantly increased over the background. The prominent PAH profiles during the haze event in Hat Yai showed a similar pattern to those in Pekanbaru. This suggested that the aerosol from the peatland fire in Indonesia was transported over long distances to southern Thailand. Moreover, the chemical mass balance model indicated that the most dominant source of PM_0.1 at both sites during normal event was vehicle fuel combustion. This is contrast with PM₁ and PM_2.5 where the biomass burning was the major source. On the other hand, during the haze event, the main source of PM_0.1 at Pekanbaru was clearly peatland fires, accounting for 51–65 %, whereas at Hat Yai, the most dominant source of PM_0.1 was vehicle fuel combustion accounting for 66 % even though the contribution from peatland fires was noticeable (17 %). This is in contrast with PM₁ and PM_2.5, where peatland fires were the main source, contributing 38–50 %.