
The Pollution Control Department reported 12 spots in the upper North with red-coded, seriously hazardous levels of PM2.5 on Tuesday morning, and the worst air pollution in Chiang Mai province.
The seriously hazardous levels of particulate matter 2.5 micrometres and less in diameter ranged from 92 to 218 microgrammes per cubic metre of air over 24 hours at these 12 locations as of 11am.