Thailand, explained.
A heavily polluted day in Chiang Mai on 2 April 2026 (Anthony Wallace/AFP via Getty Images)
Smokey season is an annual problem – but a local law could help offset regional troubles, too.
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The hazy future for Thailand’s Clean Air BillThe hazy future for Thailand’s Clean Air Bill
Travelling through Thailand’s north in April leaves you with an eerie feeling. The surrounding grey haze creates an oppressive atmosphere. You can taste it in your mouth and feel it in your chest. There’s something so unnerving about looking into the distance and not being able to see the mountains you know are there.
It feels almost dystopian, and yet it is an annual phenomenon, building to a peak in the lead up to the Thai New Year Songkran holiday in mid-April, then washed away with the rain.
This is what’s known as the smokey season. Between January and April each year, agricultural burning and wildfires contribute to a thick smog blanketing the northern provinces.
Advocates for clean air in Thailand hope the recent smoke plaguing the north will spark more urgency from the government to act. Many have pinned their hopes on the Clean Air Bill, a citizen-led piece of legislation that has been years in the making.
But as the rain subsides and the mountain views return, the fate of the bill remains murky, and there are fears the haze will be forgotten just as quickly.
The legislation could emerge from the senate as little more than a paper tiger.
Residents of the tourist hub of Chiang Mai have become accustomed to the annual haze blanketing the city. Facemasks, air purifiers and frequent checks of air quality apps are a must, as is limiting outdoor exercise. February rains created a false sense that this year might be a mild season. But by the end of March and into April, the air pollution had reached disastrous levels, with Chiang Mai regularly topping the world’s worst polluted cities list, according to monitoring site IQAir. Three provinces were declared emergency disaster zones. It prompted many who call Chiang Mai home to vacate the city at short notice, although not all can afford to.
Doctors have long warned about the dangers of PM2.5 – microscopic particles of pollution – so small they can penetrate walls and lungs, entering the bloodstream. Nosebleeds, itchy eyes, sore throats, headaches and difficulty breathing – all are symptoms associated with polluted air. PM2.5 pollution also contributes to chronic health issues, including heart disease and lung cancer.
The State of Global Air 2025 report attributed more than 50,000 deaths to PM2.5 in Thailand in 2023 alone. That same year, 10 million Thais sought health treatment for conditions linked to poor air quality. Chiang Mai University has seen a spate of faculty deaths caused by lung cancer in recent years, reportedly linked to hazardous air.
Mountains are still out there, somewhere: Chiang Mai city during the burning season (Guillaume Payen via Getty Images)
The causes of air pollution in Thailand vary by region. In the north, it’s driven by agricultural biomass burning, where farmers burn off old fields of rice, corn and sugarcane to clear the land for new crops. Thrown into this equation are wildfires caused by hot and dry conditions, as well as transboundary smoke – burning from Myanmar, Laos and Cambodia that drifts into Thailand. In the centre of the country, air quality is marred by chemical emissions from industrial factories, and in the city of Bangkok, smog is largely caused by vehicle fumes.
In Bangkok, Weenarin Lulitanonda was training for a marathon when frequent headaches forced her to stop. A former World Bank economist who co-founded Thailand’s Clean Air Network, she hopes the Clean Air Bill – which was melded together from seven submissions and took two years of drafting – will provide a strong foundation to tackle air pollution. At its core, the bill enshrines the right to clean air – “which is effectively the right to life itself, it’s a basic human right,” she says.
A central component of the legislation is a “polluter pays principle”, with hefty fines for big emitters. Those fines would be paid into a clean air fund, which would then provide subsidies and incentives to help companies and farmers transition to more eco-friendly practices.
The bill outlines a decentralised approach, so each province can deal with its unique circumstances, and seeks to improve traceability – determining the source of harmful emissions and putting the onus on companies to demonstrate their practices are clean and that their products aren’t linked to burning.
The bill was overwhelmingly approved by Thailand’s lower house in October 2025, progressing to the senate. But there it stalled. Thailand’s political upheaval saw the ousting of Paetongtarn Shinawatra and eventual installation of Anutin Charnvirakul as prime minister. Parliament was dissolved in December 2025 ahead of a snap election in February 2026, leaving the bill in limbo. Advocates had warned it could lapse and be forced to begin the parliamentary process again unless it was slated for consideration before 13 May.
With the deadline looming, there were worrying signs for proponents of the bill. Anutin said he would only back a version drafted by his conservative Bhumjaithai Party, while his deputy said harsh penalties could undermine investment at a time of global economic uncertainty. Economists at the Clean Air Network stressed that investment and economic competitiveness count for little when the air itself is harming the people.
On Friday 15 May, parliament voted to revive the bill. The eleventh-hour reprieve was a relief for the bill’s advocates, but they are not holding their breath. The legislation could emerge from the senate as little more than a paper tiger or be rejected altogether. In a country prone to political drama and systemic corruption, the future of the bill remains unclear.
Weenarin warns those in the Global North that air quality is not just an issue for Thailand or Asia, where many of the world’s factories and farms are situated. Particulate matter travels thousands of miles, crossing national borders and even oceans.
“We are under the same stratosphere, and air pollution will circulate – it has been scientifically proven that it does indeed circulate around the world. So this is everyone’s problem,” she says.
About the author
Erin Handley
Erin Handley is a freelance writer based in Thailand.
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