Chaiyoth Sresawasd1,2, Thaneeya Chetiyanukornkul3, Phuchiwan Suriyawong3, Surajit Tekasakul4, Masami Furuuchi5, Mitsuhiko Hata5, Rachane Malinee1,2, Perapong Tekasakul1,6, Racha Dejchanchaiwong This email address is being protected from spambots. You need JavaScript enabled to view it.1,7 

1 Air Pollution and Health Effect Research Center, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
2 Energy Technology Program, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
3 Department of Biology, Faculty of Science, Chiang Mai University, Mueang, Chiang Mai, 50200, Thailand
4 Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
5 Faculty of Geoscience and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
6 Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
7 Department of Chemical Engineering, Faculty of Engineering, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand

Received: March 27, 2021
Revised: July 13, 2021
Accepted: August 23, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

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Sresawasd, C., Chetiyanukornkul, T., Suriyawong, P., Tekasakul, S., Furuuchi, M., Hata, M., Malinee, R., Tekasakul, P., Dejchanchaiwong, R. (2021). Influence of Meteorological Conditions and Fire Hotspots on PM0.1 in Northern Thailand during Strong Haze Episodes and Carbonaceous Aerosol Characterization. Aerosol Air Qual. Res. 21, 210069.


  • Understanding of physicochemical characteristicsof PM0.1 in upper SEA.
  • PM0.1 concentration during haze periods was 3 times higher than non-haze periods.
  • OC and EC levels during haze period were 4 times higher than non-haze periods.
  • Lower OC and EC correlation for haze period suggested complex pattern of PM source.
  • Good OC/EC and hotspots correlation indicated more contribution of biomass burning.


Northern Thailand has long been severely affected by haze from biomass burning containing fine and ultrafine aerosols in the dry period. The carbonaceous PM0.1 comprising elemental carbon (EC) and organic carbon (OC) collected during the haze and non-haze periods in Chiang Mai, Thailand was investigated. The PM0.1 levels during the haze periods were about 3 times higher than the non-haze periods, a significant increase. PM0.1 concentration was strongly correlated with atmospheric relative humidity and the number of forest fire hotspots. Carbonaceous aerosol characteristics in PM0.1 were analyzed with the thermal/optical transmittance (TOT) method following the IMPROVE protocol. The concentrations of OC and EC, distribution of OC and EC and OC/EC ratios in PM0.1 were evaluated. Average OC and EC mass concentrations in PM0.1 were 6.8 ± 2.7 and 1.4 ± 0.5 µg m3 during the haze periods, significantly higher than those during the non-haze periods; 1.9 ± 0.9 and 0.5 ± 0.2 µg m3. The OC/EC ratio increased linearly with the number of hotspots. This indicated significant contribution from biomass burning to the PM0.1. This was strongly supported by the 48-hr backward trajectory simulation, that indicated both domestic and transboundary aerosol transports. Because both organic and elemental carbon are the light-absorbing carbonaceous aerosols, the increase during the haze periods contributed to regional air quality and climate. This study enhances the understanding of PM0.1 behavior in Chiang Mai, Thailand, during the haze periods in upper southeast Asia.

Keywords: Ultrafine particles, Carbonaceous aerosols, Forest fire, Source identification, ASEAN haze

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