Estimated effects of meteorological factors and fire hotspots on ambient particulate matter in the northern region of Thailand

Abstract

A number of studies have revealed the effects of several meteorological factors on the concentration of ambient particulate matter (PM). However, the corresponding non-linear and lagged effects of those variables on PM concentration remain unclear. This study aimed to explore the effect of meteorological variables and fire hotspot counts on PM concentration in the northern part of Thailand using the two-stage approach. In the first stage, combination of log-linear regression model and distributed lag non-linear model was used to estimate province-specific effect of meteorological factors and fire hotspots on PM2.5 and PM10 adjusting by confounders. In the second stage, the multivariate meta-analysis was applied to pool province-specific estimate, and the results showed that the negative associations of temperature, relative humidity, wind speed, and rainfall with PM2.5 and PM10 were observed, while air pressure and fire hotspot was positively associated with PM. Moreover, the effects of temperature, relative humidity, wind speed, rainfall, and fire hotspot on PM2.5 and PM10 were lasted for 5–8 days, whereas those of air pressure were peaked at lag 7 days and become attenuated toward the null afterward. In conclusion, results from this study could contribute a better understanding on the effects of meteorological variables and fire hotspots on PM concentration and induce the development of more tailored air pollution mitigation strategies depending on weather conditions.