Smog continues to cloak the upper northern region with PM2.5 dust at red-coded levels, and the worst pollution in Mae Hong Son province.
The Pollution Control Department reported that the levels of particulate matter 2.5 micrometres and less in diameter (PM2.5) ranged from 107 to 310 microgrammes per cubic metre of air over the past 24 hours as of 2pm on Tuesday.
Severe air pollution was recorded in 12 areas in upper northern provinces of Chiang Mai, Chiang Rai, Lamphun, Mae Hong Son and Nan.
PM2.5 levels:
107μg/m³ in tambon Suthep of Chiang Mai's Muang district.
113 in tambon Jong Kham of Mae Hong Son's Muang district.
114 in tambon Chang Khoeng of Chiang Mai's Mae Chaem district.
119 in tambon Chang Phueak of Chiang Mai's Muang district.
120 in tambon Sriphum of Chiang Mai's Muang district.
122 in tambon Huai Kone of Nan's Chalerm Prakiat district.
135 in tambon Li of Lamphun's Li district.
141 in tambon Wiang of Chiang Rai's Muang district.
148 in tambon Wiang of Chiang Rai's Chiang Khong district.
190 in tambon Wiang Phang Kham of Chiang Rai's Mae Sai district.
195 in tambon Muang Na of Chiang Mai's Chiang Dao district.
310 in tambon Wiang Tai of Mae Hong Son's Pai district.
Elsewhere, a red-code reading of 105μg/m³ was recorded in tambon Meechai of Muang district in the upper northeastern province of Nong Khai.
Pinsak Suraswadi, director-general of the Pollution Control Department, on Tuesday attributed the worsining air pollution, compared with that on Monday, to burning in forests, hotspots in neighbouring countries and stagnant air.
Serious pollution would continue this week, especially in the border provinces of Chiang Rai and Nan, he said.
The pollution control chief expected ultra-fine dust levels to decline from Saturday onwards.
Mr Pinsak said weather conditions in Greater Bangkok were good due to a strong wind from the South, but stagnant air was possible in some areas of the central region on Friday and Saturday.
The government decreed safe level is 50μg/m³, much higher than in most countries.
