Prime Minister Gen Prayut Chan-o-cha flew into Chiang Mai early on Tuesday to review the crisis caused by a thick blanket of smog and toxic levels of PM2.5 dust that has been choking northern Thailand for several weeks.
He demanded a clampdown on crop burning.
"I want to reiterate that the problem of hotspots (crop burning areas) must be solved in seven days," said the junta leader, who is angling to become the elected civilian prime minister.
"Nobody should ignite fires in the forest," he said.
The city’s air quality index was 379 as he visited, the worst major urban reading globally and a level that’s hazardous, according to IQAir AirVisual pollution data.
Thai authorities blame crop burning to clear farmland, as well as wildfires in mountainous forests amid a drought and searing heat.
However, Olivier Evrard, a Thailand-based specialist for the Institute of Research for Development, said crop burning was not the only culprit.
"The government has encouraged the population to buy more vehicles and coal plants are still running at full speed," Evrard said.
Chiang Mai has set up a so-called safe zone for residents in a convention centre, while a university in Chiang Rai cancelled classes on Monday and Tuesday.
'The haze usually comes and goes within a week or two, but it’s been persistent this time -- it’s the worst so far,' Khuanchai Supparatpinyo, the director of Chiang Mai University’s Research Institute for Health Sciences, said in an interview. 'This can be quite dangerous, and pose health risks.'
Screenshot from airvisual.com/thailand/chiang-mai
Northern Thailand is a popular destination for visitors during the traditional Songkran new year festival in mid-April but the smog is likely to make some holidaymakers think twice.
The seasonal duration of the haze, which used to last for about three months, has now increased to six months, according to Chaicharn Pothirat, a lung disease specialist at Chiang Mai University's Faculty of Medicine.
The long-term effects include an increase in respiratory and cardiovascular diseases, he said, adding that he is sceptical the government has any "long-term plan" good enough to tackle the problem.
"They show reporters, they fly to Chiang Mai ... but ... it does not clearly improve the situation," Chaicharn told AFP.
At the start of 2019, the military government was rattled by a second year of spiking seasonal air pollution in Bangkok, exacerbated by traffic fumes, industrial emissions and construction dust.
So far the episodes of smog haven’t damaged tourism but worsening haze could pose a challenge for an industry that’s key to economic growth.
Top Asian finance ministers and central bankers are due to have a summit in northern Thailand this week, and they’ll need pollution masks if they want to avoid breathing toxic air.
The air was classed as unhealthy in nearby Chiang Rai, where finance ministry officials and central bankers from Southeast Asian nations as well as China, Japan and South Korea will meet from Tuesday through Friday. The Bank of Thailand has said it will hand out pollution masks to media covering the event.
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