Northern provinces, especially Chiang Mai and Chiang Rai, were blanketed by unsafe levels of the carcinogenic PM2.5 on Sunday, according to the Health Department.
Dr Suwannachai Wattanayingcharoenchai, director-general of the department, said the levels of particulate matter 2.5 micrometres and less in diameter (PM2.5) exceeded 91 microgrammes per cubic metre of air in 24 hours in eight northern provinces – Chiang Mai, Chiang Rai, Lamphun, Lampang, Mae Hong Son, Nan, Phayao and Phrae.
