MIXTURE DISTRIBUTION ANALYSIS OF DAIRY AVERAGE PM2.5 CONCENTRATIONS IN BANGKOK, THAILAND

Air pollution, specifically PM2.5, poses significant health risks and global environmental challenges. Bangkok, the capital city of Thailand, also experiences severe levels of PM2.5. The objective of this study is to determine the optimal probability distribution for PM2.5 concentration in Bangkok. Daily average PM2.5 concentrations from January 1, 2018, to December 31, 2022, were analyzed at 10 monitoring sites in the Bangkok area. The concentration patterns of PM2.5 were characterized using several statistical distributions, including lognormal, gamma, and Weibull distributions, as well as 2-mixture and 3-mixture distributions. Akaike and Bayesian information criteria were utilized to identify the optimal statistical distribution fit. Results indicate that the lognormal-lognormal distribution is most suitable for the PM2.5 concentration data from stations situated along roadways. However, stations in residential areas exhibit variability in statistical distributions, likely due to distinct factors at each location. Nevertheless, it is observed that each station in Bangkok is matched to a distribution with lognormal components.