Chiang Mai had the world's worst air pollution with 180 microgrammes of PM2.5 per cubic metre of air over the 24 hours ending at 4am on Sunday, according to a leading pollution website.
The IQAir.com website ranked the northern province the most polluted on earth based on the amount of fine dust measured over the 24-hour period. Trailing in Chiang Mai's dust were Mumbai with 179µg/m³, Lahore 160µg/m³, Hanoi 156µg/m³ and Delhi 154µg/m³.
People in Chiang Mai have been unable to see Doi Suthep mountain for weeks due to the toxic smog.
The Meteorological Department predicted storms and wind in the North from Sunday to Tuesday that may ease the pollution.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported 1,061 hotspots in Thailand on Saturday while there were 4,363 hotspots in Myanmar, 2,868 in Laos, 1,182 in Cambodia, 647 in Vietnam and 32 in Malaysia.
In Thailand, 661 hotspots were found in forests and a further 192 hotspots on farmland. The northern province of Mae Hong Son had the most hotspots in the country – 127 – on Saturday.
PM2.5 was measured at 53.1 µg/m³ on average in Bangkok over the 24 hours to 4am.
