Abstract

This mini review aims to indicate how radiation inversion had an impact on PM2.5 accumulation during the winter in Thailand. Smoke sky occurred in the North and South of the country was attribute to smoke from forest fire and burnings in farmlands during September–October (Rainy season) and March–April (Summer season). While the haze sky in the wintertime was rarely observed. Until January 2018 the haze of PM2.5 occupied the sky in Bangkok and major provinces for several days and returned in December 2018 - February 2019. The radiation inversion and subsidence inversion were observed during January– February 2019, the synergy of two inversions might cause haze sky of high PM2.5 level. Radiation inversion was able to produce a double increase to the moving 24-hour PM2.5. If new target value of 24-hour PM2.5 will be applied by 2024, the reduction of PM2.5 emission based on radiation inversion’s effect should be around 25%.

Keywords: PM_2.5; Winter haze sky; Thailand