Six province in the Upper North were covered by unsafe levels of haze, the Pollution Control Department reported yesterday.

Air in the provinces contained fine particles beyond the acceptable level of 120 micrograms per cubic metre (mg/m3). The latest reading of particulate matter of up to 10 micrometres (PM10) in the province of Phayao was as high as 237 mg/m3, the agency warned.

Read more: The Nation