Chiang Mai burning season refers to the time of year when the air in Northern Thailand is filled with haze from forest fires and the burning of crop waste. Even though this is a problem across Northern Thailand, Chiang Mai has become the focus of the pollution crisis. The city has made international headlines for being the most polluted city in the world.
The fires are from when farmers burn the stubble in harvested rice fields. There are also fires from slash-and-burn farming, where new agricultural land is cleared from forest and bushland. Fires are also being lit in forests to clear forest litter to harvest mushrooms.
The fires are in Northern Thailand, as well as Laos and Myanmar. Agricultural fires are also a big issue in Central Thailand with sugarcane burning. This is one of the sources of Bangkok’s pollution crisis, and a contributing factor to transboundary haze.
The air pollution has become such a well-known issue that it’s now affecting tourism to the region. In what should be a prosperous time of year for the tourism industry, tourists are now staying away and those that can leave migrate for the burning season.
When is the Chiang Mai burning season?
The burning season typically occurs in the latter half of the dry season from February to April. There is no set dates, and varies in its severity from year-to-year.
The impact of haze on health
One of the most concerning effects of the haze crisis is its impact on public health. The smoke from burning vegetation releases harmful pollutants and particulate matter into the air, leading to respiratory issues and exacerbating pre-existing conditions.
The haze can trigger allergies, respiratory infections, and other health problems, particularly for vulnerable populations such as children and the elderly. Hospitals record an increase of inpatients that are being admitted for breathing difficulties.
Tourism and economy
Chiang Mai’s economy relies heavily on tourism, and the annual haze poses a threat to the future of this vital sector. The dangerous, persistent smog deters tourists from visiting the region, affecting local businesses, hospitality industries, and the livelihoods of those dependent on tourism.
The burning season has become so well known that tourists now know to avoid Chiang Mai in the burning season.
Efforts to address the issue
provincial and national authorities, along with environmental organisations, have been working on reducing the annual haze problem. Initiatives include promoting sustainable farming practices, implementing stricter regulations on burning, and investing in alternative land-clearing methods.
Additionally, public awareness campaigns aim to educate both farmers and the general population about the long-term consequences of open fires.
How to measure air quality
An air quality index (AQI) is an indicator of air pollution shown on a scale from 0 to 500. There are variations in measurement system between different countries, but the following scale is the most used:
0 – 50: Good (Green)
51 – 100 Moderate (Yellow)
101 – 150 Unhealthy for Sensitive Groups (Orange)
151 – 200 Unhealthy (Red)
201 – 300 Very Unhealthy (Purple)
301 and higher Hazardous (Maroon)
Two of the most popular sites that measure air quality are IQAir and the World Air Quality Index project (aqicn.org). They sometimes show different results, depending on site updates and what stations they are getting data from. One might show 120 while the other shows 130. Either way, you know the air is unhealthy. They both give a general idea of the air quality in real time.
[AQI display at Ombra Caffe detecting unhealthy air in Chiang Mai.]
If you are living in Chiang Mai the quickest way to check the air quality is to see how visible Doi Suthep is. On a clear day the green contours of the mountain are visible.
[Doi Suthep as viewed from Huay Kaew Rd and Nimmanhaemin Rd.]
As the days get hazier the mountain becomes a monotoned shape behind the smoke.
[Hazy sunset in Chiang Mai.]
On the worst days the mountain completely disappears from view.
[Doi Suthep shrouded in smoke, as viewed from Huay Kaew Rd and Nimmanhaemin Rd.]
Chiang Mai burning season news
Every year there is much handwringing from local and national politicians with promises to find a solution, yet we read the same headlines every year.
This section is an archive of news about the Chiang Mai burning season over the years. The articles show how some years are more apocalyptic than others, and it includes when announcements have been made to try and addreess the burning issue of the smoky season.
2024
Chiang Mai residents win air pollution lawsuit – [22/01/24]
“The Chiang Mai Administrative Court ruled on Friday (19 January) that the Prime Minister and the National Environment Board must complete a management plan to address local air pollution issues in 90 days.”
Chiang Mai governor orders tight measures against burning of farm waste – [10/01/24]
“Chiang Mai governor has instructed chiefs of the province’s 25 districts to intensify measures against the burning of agricultural residue in a bid to reduce PM2.5 pollution.”
2023
PM eyes tourism-crimping haze – [30/11/23]
“Prime Minister and Finance Minister Srettha Thavisin on Wednesday voiced concern over the impact of PM2.5 pollution on Chiang Mai’s tourism industry during the high season and pledged to hold talks with neighbouring countries to combat haze and smog pollution.”
Chiang Mai seeks solution to smog – [07/11/23]
“As the smog season draws nearer, Chiang Mai tourism operators are urging the government to accelerate the passage of the Clean Air Act and implement other mechanisms to reduce pollution from the agricultural sector.”
How Chiang Mai became the world’s most polluted city – [12/04/23]
“Burning fields are blamed for hazardous levels of air pollution in northern Thailand but the government is doing little to act.”
Pollution choking Thailand’s north hits tourism, worries public – [10/04/23]
As hazardous haze envelops Thailand, residents seek refuge – [13/03/23]
“Chiang Mai was rated as the most heavily polluted city in the world, exceeding the likes of Delhi, Lahore and Dhaka on air quality monitor IQAir’s real-time index of 100 major centres around the globe.”
Chiang Mai to hand out face masks as dust from fires hits hazardous levels – [08/03/23]
“Thai authorities struggle to contain forest fires, a persistent cause of air pollution during the dry season.”
It’s pollution season again – [30/01/23]
“Chiang Mai has had five data points report pollution levels at higher than 200 migrograms per cubic metre, with the Mae Chaem data centre reporting numbers as high as 284.”
2022
For fire-ravaged northern Thailand, there’s now an app to battle the blaze – [28/02/22]
‘Burning season’ ignites with 4k fires – [02/02/22]
“More than 4,000 so-called hotspots caused by slash-and-burn activities have been detected across the North as the “burning season” begins.”
2021
New data exposes Thailand’s 2021 “burning season” – [17/05/21]
“For a few months each year, Chiang Mai, northern Thailand’s tourist-friendly cultural hotspot, ranks among the world’s most polluted cities. Chiang Mai’s air pollution is largely attributable to agricultural burning rather than fossil-fuel-related combustion experienced in other global cities.”
Feeding the beast: Chiang Mai smoke seen as world’s climate change problem -[22/04/21]
“From Chiang Mai air pollution to global climate change, animal agriculture is the elephant in the room — and biochar one way to tame it.”
Bangkok fiddles whilst Chiang Mai burns – who’s behind the annual smoke season? – [21/03/21]
Holding those behind the haze to account – [21/03/21]
“Chiang Mai spent several days this month as the most polluted city on the planet, with PM2.5 levels reaching 226 microgrammes per cubic meter (?g/m³) there. The predictability of the annual surge in pollution and the lack of effective preventative action have angered city residents and concerned civil society groups.”
[Composite showing Chiang Mai city as seen from Doi Suthep on March 5 and March 10 2021, when the PM2.5 level was 70.9 and 114.4 respectively. (Photo: Gary Boyle).]
Chiang Mai among world’s most polluted cities as forest fires rage in northern Thailand – [11/03/21]
“According to AQI readings by the Pollution Control Department, five northern provinces recorded unhealthy to hazardous levels of air quality on Thursday (Mar 11). These provinces include Mae Hong Son (350), Chiang Mai (248), Chiang Rai (291), Tak (219) and Lamphun (213).”
Air pollution in Chiang Mai sends 30,000 to hospital – [10/03/21]
“Chiang Mai health officials say beyond 31,000 people have sought medical treatment for respiratory issues.”
2020
Chiang Mai smog casts pall over businesses – [03/04/20]
“Thailand’s northern region has been hit with toxic levels of air pollution due to forest fires on Wednesday, especially in the Chiang Mai province, with some areas being engulfed in air quality levels 12 times above safe levels.”
Air quality in North still ‘critical’ – [30/03/20]
“Air pollution across the upper North remains at critical levels with authorities monitoring almost 400 active hotspots in Chiang Mai alone on Sunday. The air quality did not improve on Monday morning, with IQAir recording “very unhealthy” air quality and hazardous, ultra-fine PM2.5 dust levels at 170.1 microgrammes per cubic metre (?g/m³) at 10.30am in the so-called “Rose of the North”.”
Strict no-burn zone measures to be implemented in North – [06/02/20]
“The Department of Disaster Prevention and Mitigation is coordinating with administration officials in the North and related agencies to ensure law enforcement puts out forest fires and tackles the severe air pollution.”
2019
Thailand’s famed ‘Rose of the North’ is wilting – [23/06/19]
“Ancient Chiang Mai is suffering from over-development and pollution.”
Unhealthy smoke over Thailand – [12/04/19]
“For more than a month, northern Thailand has been experiencing unhealthy, elevated levels of smoke and air pollution. The thick haze is a result of wildfires and prescribed burning by farmers clearing their land for the planting season. Meteorologists expect the unhealthy air quality to last into May.”
[NASA Earth Observatory image shows smoke and haze blanketing portions of southeastern Asia on April 12, 2019,]
On the front line with the Chiang Mai firefighters battling the flames behind the world’s worst air – [06/04/19]
Chiang Mai braces for watered-down Songkran as city chokes in smog – [05/04/19]
“Chiang Mai’s travel trade is bracing for muted Songkran celebrations as the smog crisis is likely to put a dent on visitor arrivals to the northern city and the surrounding provinces for the upcoming Thai New Year.”
Thai leader orders action to fight pollution in Chiang Mai – [04/04/19]
Thai junta chief demands action to cut smog – [02/04/19]
Chiang Mai, Chiang Rai suffer haze and smoke until at least May – [01/04/19]
Chiang Mai residents up in arms over choking smog amid government inaction – [01/04/19]
“Local authorities’ inability to deal with the severe problem – the result of a spreading forest fire – with any sense of promptness has already led to a campaign to remove Chiang Mai Governor Supachai Iamsuwan from office.”
Thailand urged to declare emergency in Chiang Mai as air pollution hits ‘disastrous’ levels – [30/03/19]
“An academic has called on the government to declare a state of emergency in Chiang Mai and most of Thailand’s northern provinces over ‘disastrous’ levels of smog.”
Northern Thailand was once a paradise. Now forest fires have made the air worse than Beijing’s. – [07/03/19]
“In mid-March, the city with the worst air pollution in the world wasn’t an industrial powerhouse populated by millions. It was Chiang Mai, the tourist-friendly cultural center in northern Thailand.”
Chiang Mai tops world pollution charts – [12/03/19]
Chiang Mai air pollution worst in the world – [13/03/19]
“The air quality index (AQI) in Chiang Mai as of 4pm Tuesday stood at 230, compared with 170 in the Bangladesh capital Dhaka and 164 in Kabul, Afghanistan, according to Air Visual, an app that monitors air quality.”
2018
We’re No. 1? Chiang Mai air pollution smashes competitors – [12/04/18]
“The “Rose of the North” won world recognition Wednesday for the dubious distinction of having the worst recorded air quality during peak conditions.”
Explaining Chiang Mai’s smoke pollution with real data – [01/04/18]
“An interview with Craig Houston, an aeronautical engineer and Chiang Mai resident who has been collecting and analysing date related to the pollution crisis.”
Chiang Mai ranked sixth worst for air pollution globally – [18/03/18]
“Air pollution in the North continues to be critical, with small dust particles of 2.5 microns in size (PM2.5) exceeding safe limits at almost every air-quality testing station.”
2017
Chiang Mai has worst small particle pollution in Thailand: Greenpeace – [18/05/17]
“Chiang Mai is Thailand’s most-polluted city in terms of dangerously small pollutants which kill tens of thousands in Thailand annually”.
2016
Thailand: Air quality levels in Chiang Mai reaches unhealthy levels – [19/04/16]
“The air quality in northern Thailand, particularly Chiang Mai, has reached unhealthy levels, with the Air Quality Index (AQI) at the time of publishing registering at 113, which is considered unhealthy for sensitive groups.”
Smog causing health woes for thousands in Chiang Mai – [18/04/16]
“Thousands of people in Chiang Mai have developed symptoms that can be linked to air pollution this month.”
2015
Amid northern haze, a burning desire for wealth – [29/03/15]
“As the seasonal smoke worsens, the forest fires caused by a lucrative mushroom trade and other foragers are only exaggerating the problem.”
Smog shrouds northern Thailand as air pollution hits unhealthy levels – [03/03/15]
“Northern Thailand was shrouded in smog as air pollution hit unhealthy levels in some areas, due to uncontrolled burning and wild fires.”
2014
Transboundary pollution in Northern Thailand causes dangerous levels of smog – [26/03/14]
“Chiang Mai, the largest city in the North and second-largest in the country, announced this year’s first day of “unsafe” air quality on March 11. Levels of PM10 (particulate matter of less than 10 microns) rose above the Thai government’s threshold of 120 micrograms per cubic meter (ug/m3). Neighboring provinces have since reported similarly hazardous measurements. By comparison, PM10 in Bangkok has hovered between 40 and 50 during this same period.”
Chiang Mai air quality health threat – [14/03/14]
“Air quality measurements in Chiang Mai have registered above the ‘healthy’ spectrum for three consecutive days.”
2012
[Stop Burning – April 2012.]
Haze spreads across north: Thailand – [27/02/12]
Links and resources
Causes and solution of forest and agricultural burning in Northern, Thailand [PDF]
International Journal of Agricultural Technology 2022Vol. 18(4):1715-1726
Seasonal Patterns and Trends of Air Pollution in the Upper Northern Thailand from 2004 to 2018
Volume 22, Issue 5, May 2022.