Satellite photos show hotspots increasing in the North, indicating farmers have started seasonal burning, but air quality remains good, according to the army.
An army commander said on Monday that from Dec 6-12 the levels of PM2.5 in 17 northern provinces ranged from 18 to 42 microgrammes per cubic metre (µg/m³) of air over 24 hours. The local safety threshold was set at 50 µg/m³ .
The highest level of PM2.5 was measured in Tak, he said.
"Overall air quality in the North remains good but seasonal field burning is increasing, to prepare land for cultivation," he said.
Satellite-based imaging from Dec 6-12 showed 869 hotspots in the North and most of them, 532, were on farm land. There were 170 hotspots in forest reserves, he said.
Uttaradit province had the largest number of hotspots, 149, and Chiang Rai the widest area of hotspots.
