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.
The hazardous air pollution was recorded in 21 areas in the northern provinces of Chiang Mai, Chiang Rai, Lampang, Lamphun, Mae Hong Son, Nan, Phayao and Phitsanulok.
The PM2.5 levels in the North were:
98μg/m³ in tambon Hang Dong of Chiang Mai's Hot district,
108 in tambon Nai Muang of Phitsanulok's Muang district,
117 in tambon Jong Kham of Mae Hong Son's Muang district,
119 in tambon Chang Khoeng of Chiang Mai's Mae Chaem district,
128 in tambon Mae Moh and tambon Sop Pad of Lampang's Mae Moh district,
131 in tambon Ban Klang of Lamphun's Muang district,
132 in tambon Ban Dong of Lampang's Mae Moh district,
133 in tambon Suthep of Chiang Mai's Muang district,
139 in tambon Li in Lamphun's Li district,
146 in tambon Nai Wiang of Nan's Muang district,
148 in tambon Chang Phueak of Chiang Mai's Muang district,
152 in tambon Ban Tom of Phayao's Muang district,
153 in tambon Phrabat in Lampang's Muang district,
159 in tambon Wiang of Chiang Rai's Muang district,
166 in tambon Sriphum of Chiang Mai's Muang district,
193 in tambon Huai Kone of Nan's Chalerm Prakiat district,
258 in Tambon Wiang of Chiang Rai's Chiang Khong district,
265 in tambon Wiang Phang Kham of Chiang Rai's Mae Sai district,
269 in tambon Wiang Tai of Mae Hong Son's Pai district,
and 277 in tambon Muang Na in Chiang Mai's Chiang Dao district.
Red-coded levels of PM2.5 were also recorded in two areas in the Northeast: 95 in tambon Kut Pong of Loei's Muang district and 116 in tambon Meechai of Nong Khai's Muang district.
Air quality map of Thailand on Thursday afternoon. (Screenshot: IQAir).
The government has set the safe threshold for PM2.5 at 50μg/m³.
PCD director-general Pinsak Suraswadi said on Thursday that PM2.5 levels were rising in the North and the Northeast due to hotspots in the country and neighbouring countries.
However, he said air pollution is expected to decrease from next Tuesday due to stronger winds.