Smog levels continued to rise on Wednesday morning with PM2.5 dust readings exceeding 200 microgrammes per cubic metre of air in three northern provinces, including Chiang Mai.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported at 9am that 20 provinces recorded red (seriously harmful) levels of particulate matter 2.5 micrometres and less in diameter (PM2.5). They ranged from 76.1 to 227.2 microgrammes per cubic metre of air over the past 24 hours. The government-set safe threshold is 37.5µg/m³.
The worst level, 227.2µg/m³, was measured in the northern province of Mae Hong Son, followed by 209.2 in Chiang Rai, 208.5 in Chiang Mai, 183.4 in Phayao, 173.8 in Nan, 171.4 in Lamphun, 154.5 in Lampang, 133.3 in Phrae, 110.9 in Uttaradit, 101.8 in Loei, 100.1 in Tak, 96.4 in Nakhon Phanom, 91.0 in Udon Thani, 89.5 in Bueng Kan, 87.0 in Sakon Nakhon, 86.2 in Nong Khai, 86.0 in Nong Bua Lam Phu, 85.5 in Sukhothai, 81.7 in Kalasin and 76.1 in Mukdahan.
Orange (initially unsafe) levels of PM2.5 were detected in 19 other provinces. Readings ranged from 39.1 to 67.9µg/m³.
The provinces were, in descending order, Khon Kaen, Phitsanulok, Amnat Charoen, Phetchabun, Kamphaeng Phet, Ubon Ratchathani, Maha Sarakham, Chaiyaphum, Roi Et, Yasothon, Kanchanaburi, Uthai Thani, Phichit, Si Sa Ket, Nakhon Ratchasima, Surin, Buri Ram, Nakhon Sawan and Ratchaburi.
Provinces in the lower Central Plain, the lower Northeast, the East and the South had moderate and good air quality. The eastern province of Rayong had the best air quality with 15.5µg/m³, followed by Trat with 15.9µg/m³ also in the East.
The intensity of red-coded PM2.5 levels was higher than on Tuesday.
The map by Gistda shows the red zones of PM2.5 shroud the North, the upper Central Plain and the upper Northeast on Wednesday morning.