A clear day in most of Bangkok, with unsafe smog levels in only five districts on Wednesday morning.
The Bangkok Metropolitan Administration reported levels of particulate matter 2.5 micrometres and less in diameter (PM2.5) ranged from 33 to 57 microgrammes per cubic metre of air over the previous 24 hours. The government-set safe threshold is 50mcg.
Unsafe levels were reported in five districts - Bang Kapi, Bung Kum, Laksi, Lat Krabang and Wang Thonglang. The highest were in Bung Kum and Wang Thonglang.
On Tuesday morning, unsafe levels were detected in 27 districts.
In other provinces on Wednesday morning, PM2.5 levels were at 13-82mcg.
The worst pollution was in Muang district of Loei province. The best air quality was in Muang district of Satun province, according to the Pollution Control Department.
Unsafe levels were also reported in some districts of Kanchanaburi, Khon Kaen, Lampang, Loei, Nakhon Ratchasima, Nan, Phayao, Phrae, Prachin Buri, Sa Kaeo, Saraburi, Suphan Buri and Tak provinces.