The mountain is protected as the only locale in Thailand where “sub-alpine vegetation” grows.

Meanwhile the charred remains of monkey, junglefowl and peacock have been found in the ashes of forest fires.

Fire-fighters extinguished two major blazes on Doi Luang Chiang Dao this week, at Tham Chiang Dao and Doi Sam Phi Nong, but not before 400 rai of trees were burned off.

As specialists were about to inspect damage to vegetation and wildlife, Chiang Dao wildlife sanctuary chief Pakasit Rawiwan said, another fire ignited on nearby Doi Nang.

Teerawat Thongma of the Chiang Dao organic-farming group said on Wednesday the forest fires burning on Doi Luang Chiang Dao since March 27 had posed a serious threat to sub-alpine vegetation and protected wildlife.

Similar situations exist elsewhere in the upper North, where naturally occurring forest fires and deliberately lit outdoor fires were together amounting to 793 hotspots as of 3am Wednesday.

The Geo-Informatics and Space Technology Development Agency said Mae Hong Son had 372 hotspots, Chiang Mai 161 and Chiang Rai 112.

The smog crisis in Chiang Mai is now in its third consecutive week with many areas choking on dangerous levels of PM2.5 – airborne particulates 2.5 microns or less in diameter.

Hourly reports on the website of the Chiang Mai Air Quality Health Index Centre (cmaqhi.org) through the morning showed PM2.5 at its highest concentration in the tambon of Yang Mern of Samoeng district, measuring 618 micrograms per cubic metre of air.

The safe limit in Thailand is 50.

The Chiang Mai University rector’s office in Chang Pheuk, Muang Chiang Mai, was measuring 282mcg of PM2.5, but that dropped to 90 by 11am. Yang Mern also fell, to 296.

The later measurements showed the levels at Chiang Dao at 400mcg and Mae Na and Ping Kong in Chiang Dao district at 371 and 358, respectively.

The Pollution Control Department at 9am on Wednesday put the 24-hour average of PM2.5 in nine northern provinces between 29 and 277mcg.

Tambon Jong Kham in Muang Mae Hong Son was worst off at 277mcg, followed by Wiang Phang Kham in Chiang Rai’s Mae Sai (162) and Chang Pheuk in Muang Chiang Mai (130).

Chiang Mai’s other three stations also cited high levels – Sri Phum and Suthep in Muang at 109 and 77, and Chang Kerng in Mae Chaem at 111.