PM2.5-Bound Fatty Acids and Oxidative Potential: A Year-Round Study in Chiang Mai, Upper Northern Thailand
Authors:   Environment and Health Research Group, Research Institute for Health Sciences (RIHES), Chiang Mai University, Chiang Mai 50200, Thailand, Santijitpakdee Teetawat ,   School of Health Sciences Research (SHSR), Research Institute for Health Sciences (RIHES), Chiang Mai University, Chiang Mai 50200, Thailand,   School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China; Atmospheric Environment Center, Joint Laboratory for International Cooperation on Climate and Environmental Change, Ministry of Education (ILCEC), Nanjing University of Information Science & Technology, Nanjing 210044, China., Prapamontol Tippawan ,   Environment and Health Research Group, Research Institute for Health Sciences (RIHES), Chiang Mai University, Chiang Mai 50200, Thailand, Ponsawansong Pitakchon ,   Environment and Health Research Group, Research Institute for Health Sciences (RIHES), Chiang Mai University, Chiang Mai 50200, Thailand, Kawichai Sawaeng ,   Environment and Health Research Group, Research Institute for Health Sciences (RIHES), Chiang Mai University, Chiang Mai 50200, Thailand, Song Wenhuai ,   School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China; Atmospheric Environment Center, Joint Laboratory for International Cooperation on Climate and Environmental Change, Ministry of Education (ILCEC), Nanjing University of Information Science & Technology, Nanjing 210044, China, Cao Fang ,   School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China; Atmospheric Environment Center, Joint Laboratory for International Cooperation on Climate and Environmental Change, Ministry of Education (ILCEC), Nanjing University of Information Science & Technology, Nanjing 210044, China, Zhang Yan-lin ,   School of Ecology and Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China; Atmospheric Environment Center, Joint Laboratory for International Cooperation on Climate and Environmental Change, Ministry of Education (ILCEC), Nanjing University of Information Science & Technology, Nanjing 210044, China
Published: September 2024

Air pollution study mostly targeted in components of fine particulate matter (PM2.5, particulate matter with aerodynamic diameter ≤ 2.5 µm) but their health implication is still scarce. Fatty acids could exhibit surfactant properties of PM2.5. We investigated the oxidative potential (OP) of PM2.5-bound fatty acids in Chiang Mai, upper northern Thailand: a year-round study in 2021. A dithiothreitol (DTT), an acellular assay, was used to evaluate the OP of eighty-nine PM2.5 filters collected from January to December 2021. A series of PM2.5-bound fatty acids i.e., C14:0–C30:0 fatty acids were determined by gas chromatography/mass spectrometry (GC/MS). Total fatty acids (C14:0–C30:0 and C18:1, C18:2) accounted for 498.7 ± 196.1 and 206.9 ± 112.8 ng/m³ in high biomass burning (HBB) and low biomass burning (LBB) periods, respectively. Mean values of OPDTTv (OP normalized by air volume of sampling) in HBB and LBB periods were 0.13 ± 0.06 and 0.03 ± 0.03 nmol/min/m³, respectively. Long chain saturated fatty acids (C22:0-26:0) mostly showed moderately significant correlation with OPDTTv (r = 0.33-0.47, P < 0.01) in HBB period but showed no significant correlation in LBB period. Meanwhile, linoleic acid (C18:2) was the only individual compound among unsaturated fatty acids that significantly correlated with OPDTTv (r = 0.39, P < 0.01). These findings suggest that PM2.5-bound fatty acids, particularly during open-biomass burning period, contribute to variations in oxidative potential, potentially influencing the health risks associated with PM2.5 exposure.