Hazardously thick smog shrouded 37 of the 77 provinces on Monday morning, mostly in the North where Chiang Rai residents suffered under the worst level of PM2.5 dust.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported at 11am on Monday that seven northern provinces were facing red (seriously harmful) levels of particulate matter 2.5 micrometres and less in diameter (PM2.5), ranging from 80.5 to 107.5 microgrammes per cubic metre of air over the past 24 hours. The government-set safe threshold is 37.5µg/m³.
The worst level, 107.5, was measured in Chiang Rai, followed by 103.8 in Chiang Mai, 92.8 in Phayao, 87.8 in Mae Hong Son, 82.9 in Nan, 80.6 in Lamphun and 80.5 in Lampang.
Orange (initially unsafe) levels of PM2.5 were detected in 30 other provinces, mostly in the Northeast. They ranged from 37.9 to 72.4µg/m³.
The provinces were, in descending order, Loei, Tak, Phrae, Uttaradit, Nong Khai, Nong Bua Lam Phu, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Sukhothai, Phitsanulok, Kalasin, Khon Kaen, Chaiyaphum, Mukdahan, Kamphaeng Phet, Phetchabun, Amnat Charoen, Maha Sarakham, Nakhon Ratchasima, Buri Ram, Roi Et, Ubon Ratchathani, Uthai Thani, Yasothon, Surin, Si Sa Ket, Kanchanaburi and Phichit.
Provinces in the lower Central Plains, the East and the South had moderate and good air quality. Samut Songkhram had the best air quality with 15.0µg/m³ of PM2.5, followed by Narathiwat with 15.4µg/m³.
Prime Minister Srettha Thavisin wrote on social media on Monday that the government was doing its best to control smog and help affected people but burning continued inside the country and nearby.
Chiang Mai governor Nirat Pongsitthaworn told reporters on Monday that local administrative organisations and hospitals would have clean air rooms ready for local residents, and face masks.
The Faculty of Medicine at Chiang Mai University said PM2.5 pollution was a major factor in the rising incidence of lung cancer, and was seriously affecting respiratory and cardiovascular patients. Over the past two weeks, the number of patients with nose bleeding, eye irritation, asthma and rashes had increased.