
Unhealthy levels of particulate matter 2.5 micrometres or less in diameter (PM2.5) were recorded in 23 areas, mostly in the North, with the worst levels found in Chiang Mai, the Pollution Control Department reported on Thursday.
As of 11am on Thursday, PM2.5 dust levels ranged from 98 to 277 microgrammes per cubic metre (μg/m³) of air in the North over the past 24 hours.