Biomass burning sources and their contributions to PM10 concentrations over countries in mainland Southeast Asia during a smog episode

Severe particulate matter problems are known to occur frequently in mainland Southeast Asia (MSEA) during times of intensified biomass burning (BB). Therefore, the objectives of this study are to investigate BB characteristics and their impacts on PM10 concentrations in MSEA during a smog episode that took place in March 2012. According to the analysis of our study, PM10 was emitted from BB and accounted for 72% of all sources. Using the WRF-CMAQ modeling system, the current study showed that severe PM10 levels in MSEA exceeded the World Health Organization (WHO) ambient air quality standard (AAQS) recommended safe level of air quality by 51%. Subsequently, based on aggregated monthly data, the area average PM10 concentration was found to be 80 μg/m3 over MSEA. In addition, the model showed that the major source of particulate matter was from BB and contributed to 49% of ambient PM10 concentrations in MSEA while it specifically contributed 73%, 69%, 59%, 45%, 33%, and 31% in Laos, Myanmar, Cambodia, Thailand, China, and Vietnam, respectively. Based on a sensitivity analysis, we found that every 1 Tg of PM10 increased in MSEA would result in a 27.8 μg/m3 increase in PM10 concentrations in MSEA. However, these research findings tend to vary from one country to another, where for every 1 Tg of PM10 increased, it would result in a 60.6, 50.8, 17.6, 14.1, 13.0, and 9.9 μg/m3 increase in PM10 concentrations in Laos, Myanmar, Thailand, China, Cambodia, and Vietnam, respectively. These findings assume great significance those who wish to establish PM10 control strategies at both regional and national levels, given that BB needs to be recognized as the primary genesis of PM10 problems. [Display omitted] •A case study was conducted during the peak biomass burning month from 2011 to 2019.•Biomass burning contributed 72% of PM10 emission in MSEA.•Biomass burning contributed 49% of ambient PM10 concentrations in MSEA.•The largest influence from biomass burning was found in Laos and Myanmar.