Ambient Nanoparticles (PM_0.1) Mapping in Thailand

Nanoparticles (NPs), nanoaerosols (NAs), ultrafine particles (UFPs), and PM_0.1 (diameters ≤ 0.1 µm or 100 nm) are used interchangeably in the field of atmospheric studies. This review article summarizes recent research on PM_0.1 in Thailand. The review involved peer-reviewed papers that appeared in the Scopus and the Web of Science databases and included the most recently published articles in the past 10 years (2013–2022). PM_0.1 mainly originate from combustion processes such as in motor vehicles. The highest mass concentration of PM_0.1 occurs during the dry season, in which open fires occur in some regions of Thailand. The northern area of the country has higher PM_0.1 mass concentrations, followed by the central and southern areas. Carbonaceous nanoaerosols are produced during normal periods, and the proportions of organic to elemental carbon and char to soot suggest that these originate from motor vehicles. However, in haze periods, biomass fires can also produce carbon-containing particles. PM_0.1 pollution from local and cross-border countries also needs to be considered. The overall conclusions reached will likely have a beneficial long-term impact on achieving a blue sky over Thailand through the development of coherent policies and managing new air pollution challenges and sharing knowledge with a broader audience.