Spatial-temporal variability and heath impact of particulate matter during a 2019-2020 biomass burning event in...

To understand the characteristics of particulate matter (PM) in the Southeast Asia region, the spatial-temporal concentrations of PM₁₀, PM_2.5 and PM₁ in Malaysia (Putrajaya, Bukit Fraser and Kota Samarahan) and Thailand (Chiang Mai) were determined using the AS-LUNG V.2 Outdoor sensor. The period of measurement was over a year from 2019 to 2020. The highest concentrations of all sizes of PM in Putrajaya, Bukit Fraser and Kota Samarahan were observed in September 2019 while the highest PM₁₀, PM_2.5 and PM₁ concentrations in Chiang Mai were observed between March and early April 2020 with 24 h average concentrations during haze days in ranges 83.7-216 µg m^-3, 78.3-209 µg m^-3 and 57.2-140 µg m^-3, respectively. The average PM_2.5/PM₁₀ ratio during haze days was 0.93 ± 0.05, which was higher than the average for normal days (0.89 ± 0.13) for all sites, indicating higher PM_2.5 concentrations during haze days compared to normal days. An analysis of particle deposition in the human respiratory tract showed a higher total deposition fraction value during haze days than on non-haze days. The result from this study indicated that Malaysia and Thailand are highly affected by biomass burning activity during the dry seasons and the Southwest monsoon.