Air pollution remained above the safety limit in Chiang Mai on Friday, the first day of a 50-day ban on all burning.
In neighbouring Mae Hong Son, the level of PM2.5 – airborne particulates 2.5 microns or less in diameter – was 93 micrograms per cubic metre of air – nearly double the safe limit of 50mcg.
The Pollution Control Department said PM2.5 levels ranged from 35 to 93mcg across the upper North at 9am on Friday.
The worst pollution earned the tambon of Jong Kham in Muang Mae Hong Son “code red status” with 93mcg of PM2.5 and an Air Quality Index level of 102.
Mae Hong Son, where numerous forest fires are raging, has also implemented a ban on outdoor burning that will be in effect through April.
PM2.5 haze was thick in Phra Baht in Muang Lampang at 67mcg, Mae Mo in Lampang at 64, Chang Pheuk (64) and Sri Phum (63) in Muang Chiang Mai, Na Chak in Muang Phrae at 59 and Mae Pa in Tak’s Mae Sot district, also at 59.
Chiang Mai has banned outdoor burning until April 20, having hit an AQI of 193 on Thursday according to airversual.com.
Regional Health Promotion Centre 1 in the tambon of Chang Klan remained closed on Friday because of the haze.
A campfire lit by people gathering items in the woods is believed to have triggered a forest fire on Thursday afternoon in Ban Huai Tak (Moo 3) in Lampang’s Ngao district.
It was extinguished within in an hour, but not before burning off four rai of trees and shrub, said Huai Tak forest-fire control unit chief Pairoj Ajiriya.