Is Southeast Asia ready for PM0.1? Ultrafine particulate pollution at the frontier of regional air quality research
摘要
Ultrafine particles (UFP), nanoaerosols (NA), nanoparticles (NP), and PM0.1 (particles with dp ≤ 0.1 μm, or 100 nm) are derived from both natural and human-caused sources. Combustion-related activities, including biomass burning, traffic emissions, and industrial processes, represent the dominant primary sources of PM0.1. In addition to direct emissions, PM0.1 can also form through atmospheric photochemical reactions and secondary particle formation processes influenced by meteorological conditions. The review article was based on over 90 peer-reviewed papers, mainly from the Scopus and Web of Science databases, with the most recent papers published within the past 10 years (2016–2025). Ambient PM0.1 concentrations are generally higher in many Asian countries than in Europe and North America. However, current knowledge of PM0.1 in Asia remains limited due to insufficient monitoring infrastructure, incomplete emission inventories, and a lack of comprehensive understanding of regional transport processes and associated public health impacts. Elevated PM0.1 concentrations have been frequently observed across Southeast Asia, particularly during seasonal biomass-burning haze episodes. This review synthesizes current knowledge on ambient PM0.1 in Southeast Asia, focusing on sources, formation mechanisms, spatial and temporal patterns, and potential health implications. Strengthening the scientific understanding of PM0.1 is essential for advancing air quality management strategies and improving the capacity to predict and mitigate nanoparticle pollution across Southeast Asia.