Fine dust pollution exceeded the safe threshold in 45 of the 48 areas of greater Bangkok on Thursday, with the worst in Bangkok's Bung Kum district, the Pollution Control Department reported.
The levels of particulate matter 2.5 micrometres and less in diameter were measured at 47-81 microgrammes per cubic metre of air over the past 24 hours. The safe threshold is set at 50mcg.
It reached 81mcg in Bung Kum.
Other unsafe areas included Bang Khunthian, Bang Na, Din Daeng, Pathumwan, Thon Buri, Wang Thonglang and Yannawa districts of Bangkok.
Toxic levels of PM2.5 were also reported in Bang Kruai and Pakkret districts of Nonthaburi; Khlong Luang district of Pathum Thani; Bang Sao Thong and Phra Pradaeng districts of Samut Prakan; and Muang district of Samut Sakhon, the department reported.