Unsafe levels of PM2.5 dust covered Bangkok and 23 provinces, mostly in the Central Plains, on Monday morning.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported at 6am that unsafe levels of PM2.5 ranged from 37.6 to 50.6 microgrammes per cubic metre (µg/m³) of air in Bangkok and 23 provinces. The government-set safe threshold for PM2.5 is 37.5µg/m³.
The highest level, 50.6µg/m³, was recorded in Samut Sakhon province in the Central Plains.
Other places blanketed with thick and harmful smog included Pathum Thani, Nakhon Pathom, Bangkok, Ayutthaya and Chon Buri.
Very good air quality was detected in 12 provinces where PM2.5 levels were between 8.9 and 14.4µg/m³, including Mae Hong Son, Chiang Rai and Phatthalung.
Other provinces had either good or moderate air quality.
The Meteorological Department said the smog was due to stagnant air which would continue until Wednesday.
