Smoke in Chiang Mai is a nuisance in late winter so, if you don’t have a $100 Hatari Room Air Purifier get it now (from Siam TV)!
If you DO have an air purifier, it’s time to change your filter! That’s my old filter from last year’s smoke season beside the new filter, at right!Smoke Filter
From memory, a replacement Hatari filter (RAP-1201 HEPA Activated Carbon) costs around 1100 Baht. Highly recommended!

Chiang Mai doesn’t have the usual seasonal progression. Our seasons begin when the rains stop in November and the mornings turns chilly. Last year it was so cold that people with old-style, unsealable, Thai houses had to move in with friends whose homes–though unheated–could at least be sealed by closing windows and doors! The cool weather and clear blue skies persist until sometime in March when temperatures rise. And rise. And rise until the afternoons are just plain hot. Since the rains have not started, local Hill Tribes burn off the underbrush to encourage mushroom growth, as you see in the photograph (right). That’s Doi (Mt.) Suthep, our sacred mountain, being burned off. Only this year, as you see, there were only a few burn sites and those were soon extinguished. The forest rangers have been cracking down on fire-starters and Mother Nature has helped with regular rains and, gasp! cloudy skies. The net result is the best hot season in living memory: almost-blue skies and pleasant temperatures. Perhaps the smoke season will soon be a memory…

Underbrush burning is the cause of smoke in Chiang Mai, which us part of the Southeast Asian haze–a fire-related large-scale air pollution problem that occurs every dry season in Brunei, Indonesia, Malaysia, Singapore, the Philippines and Thailand. Its official name is Southeast Asian Transboundary haze and it’s been recorded almost every year since 1972. It’s part of the price we pay for economic development.

Smoke in Chiang Mai
Smoke in Chiang Mai

Breaking News:  Singapore proposed that ASEAN nations put an end to the practice of burning foliage and provided satellites and software for our intrepid rangers, who have been snuffing out fires before they get a hold on the hillsides. Old Asia Hands laughed: nothing would change, they said. But Chiang Mai has had mostly blue skies this season, 50 people have been fined 5,000 baht and the fine money given to informers. Though the level of potentially dangerous airborne particle matter in Chiang Mai rose beyond the safe limit on Saturday, the Disaster Prevention Department sent out more frequent patrols of forestland by fire-watch volunteers, strictly controlling farmlands and highway-side areas and asking for residents’ cooperation to refrain from burning garbage and farm waste.
We’ve still got a ways to go before we have blue skies every day (after all, the indigenous people have practiced slash and burn agriculture for centuries) but–at long last–the authorities are starting to get a handle on it, and that’s good news.

Chiang Mai Smoke
Chiang Mai Smoke

Most of the haze is caused by illegal agricultural fires. The worst, in Indonesia–especially from the provinces of South Sumatra and Riau in Indonesia’s Sumatra island and Kalimantan, where it’s carried out on an industrial scale because burned land sells at a higher price for activities like oil palm and pulpwood production. Burning is cheaper and faster than cutting and clearing, too.

The least bad is the northern Thailand smoke, which comes almost exclusively from Hill Tribes’ burning of underbrush in preparation for the great annual mushroom harvest when the monsoon begins. One reason the locals complain so little about it is that they love mushrooms more than clear skies. The Hill Tribes make 20% of their incomes by harvesting mushrooms. Our local hills produce some of the most exotic edible fungi on earth, and wealthy Bangkokians pay a fortune to have them rushed to them. The most reliable way to ensure that the mushrooms set spores is to burn the underbrush during the dry season. That’s where the smoke comes from.

It does irritate some people, and they usually choose that as their beach time. But most locals ignore it (while complaining about it, too). Even though I grew up with asthma and have all kinds of nasal allergies still, it doesn’t bother me. My guess is that human beings evolved with the kind of ‘agriculture’ that the tribespeople are practicing. Wood and brush smoke are something our lungs have been dealing with for millions of years, so we handle it with relative ease.
That’s my story, anyway, and I’m sticking to it.

The health effects of haze are mainly caused by the irritant effects of fine particles on the nose, throat, airways, skin and eyes. The health effects of haze depend on its severity as measured by the Pollutants Standards Index (PSI). There is also individual variation regarding the ability to tolerate air pollution. Most people would at most experience sneezing, running nose, eye irritation, dry throat and dry cough from the pollutants. They are mild and pose no significant danger to the health of the general population.

But people with active medical conditions like asthma, chronic lung disease, bronchitis, chronic sinusitis and allergic skin conditions are more likely to be  severely affected and may experience more severe symptoms. Children–with their more rapid metabolisms and the elderly, with their lowered resistance, are more likely to be affected. For some, symptoms may worsen with physical activity.

This documentary, by Chiang Mai filmmaker and photographer Marisa Marchitelli, gives you a sense of Chiang Mai smoke from February through March:

8 Responses

  1. I have been reading for many years about the annual smoke / low air quality problem in Chiang Mai. All of these articles identified local farmers burning their rice fields to prepare for the new harvest. Your article is the only 1 I have read that talks about mushroom crops being the crop helped by this scorched earth burning, and not rice fields. I wish to move there soon and I very much wish to understand this issue. Is the smoke related to rice and mushroom crops, or just mushroom crops in your opinion??

    1. Rice stubble (stalks, etc.) is not a significant contributor to air pollution. Most of it is used for other purposes and what little is burned burns quickly and with little smoke. The haze we see is 95% from underbrush and land clearing. Most of the land clearing is done to prepare for palm oil planting and the majority of that is in Indonesia–even though we get that haze in Thailand.
      Hope this helps!

  2. An interesting and informative read. I did not know about the relationship between the mushroom harvest and slash and burn. I have lived in Chiang Mai and now Krabi for several years. I was in Chiang Mai a couple of weeks ago to help a friend post surgery. The air was so bad, I had my first asthma attack in years and acute bronchitis. I made two visits to the pulmonologist at CM Ram and had respiratory therapy. I am otherwise healthy and active, and have now fully recovered back in Krabi’s blue skies. It would be wonderful if something is finally done to change hearts and minds away from this antiquated practice that is no longer viable in a world with 6+ billion people. I love Chiang Mai but cannot stay in the north this time of year. I am hopeful but skeptical.

    1. The haze and, seasonally, smoke, is throughout SE Asia, but lessens along the coastlines, for obvious reasons. Most countries have begun taking steps to reduce it and, at least in Northern Thailand, air quality has markedly improved this year!

      1. I live in Chiang Mai and have been for a few years; I don’t think the air is better now at all. It is now almost June and still hazy with a 2.5 Index of 135. This year, particularly, seems to be the worst so far. Started in Feb and…still hazy.

  3. July 2020
    It is really difficult to know what to make of this article, beyond it is mostly nonsense, although understandable it was written a while ago.
    I live in Chiang Mai, and almost daily drive out of the city to photograph insects; this last winter there were new fires almost daily in the ‘fire’ season, close to the main roads, never mind in the hills.
    This winter, and last, the situation regarding the fires was particularly bad, indeed dreadful.
    The hill tribe people may have something to do with the problem, but overall it appears that are not alone at all, and have little to do with the overall issues.

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