CHIANG RAI – Thailand’s National Environment Committee has taken decisive action to tackle the country’s worsening air quality. Led by Deputy Prime Minister Prasert Jantarawongtong, the committee has officially declared Chiang Rai, Chiang Mai, Lamphun, Mae Hong Son, and Bangkok as PM2.5 control zones.
This was formalized on September 8, 2025, after the Supreme Administrative Court ruled on August 1, 2025, that the National Environment Board must act in line with the National Environmental Quality Promotion and Preservation Act of 1992.
The declaration, set to be published in the Royal Gazette within ninety days, represents a marked shift towards addressing the persistent PM2.5 haze that plagues these regions each year and threatens the health of millions.
For more than ten years, northern provinces like Chiang Rai, Chiang Mai, Lamphun, and Mae Hong Son have faced heavy haze every year, with the worst conditions between February and May. This “burning season” sees smoke and fine particles fill the air, caused by both local and overseas sources.
Bangkok also struggles with worsening air quality, especially during the dry months from November to March. The main concern is PM2.5—tiny particles that are less than 2.5 micrometres in diameter, small enough to reach deep into the lungs and bloodstream.
Exposure to PM2.5 is linked to breathing problems, heart disease, and even early deaths.
In Chiang Rai, thick haze has become part of daily life in recent years, often hiding the region’s well-known mountains and turning green hills into a muted grey scene.
In March 2023, drone videos from Mae Sai district showed city buildings barely visible under heavy smog; PM2.5 levels stood at 163 micrograms per cubic metre (µg/m³), over ten times the World Health Organization’s safe 24-hour limit of 15 µg/m³.
In Chiang Mai, a key tourist city, PM2.5 hit 269.2 µg/m³ on March 31, 2023, according to IQAir, ranking it among the world’s most polluted cities. Bangkok hasn’t fared much better, with levels jumping to 119 µg/m³ in January 2025, forcing schools and offices to close.
Health Effects and Public Concern
The impact on public health has been serious. In 2019, Greenpeace Thailand reported that PM2.5 pollution contributed to 29,000 early deaths across 36 provinces, with a higher toll than traffic crashes, drugs, and violent crime combined.
Dr. Veera Isarathanan at Mae Chan Hospital in Chiang Rai expressed worry for newborns, who cannot wear masks and must breathe polluted air as their lungs develop. The Chiang Mai Provincial Public Health Office has tracked increases in hospital visits during smoky periods.
A 2011 study recorded a 26 percent jump in outpatient treatments and a 33 percent rise in admissions for breathing problems during haze events.
The sources of PM2.5 in Thailand come from both inside and outside the country. In the north, crop burning is a major factor, as farmers set fire to rice, sugarcane, and maize fields before new planting. Forest fires, often started for foraging, make things worse, especially in Mae Hong Son’s Pai district, which recorded 255 µg/m³ of PM2.5 in April 2023.
NASA found fire activity at its peak in March and April, with thousands of hotspots recorded across Thailand, Myanmar, Laos, and Cambodia. Research published in 2023 showed that most of Chiang Mai’s air pollution comes from other provinces and countries, with 37 percent from Myanmar and 28 percent from Laos.
In Bangkok, car exhaust takes centre stage. The city has 3.2 million diesel vehicles, many of which still meet only Euro 4 emission standards and pump out high levels of particles. Industry, waste burning, and power plants using fossil fuels add to the problem.
The city’s shape, with tall buildings and a low basin, helps trap these particles, while similar barriers in the north’s mountain valleys make it hard for polluted air to clear.
Moving Towards Solutions
Officially naming Chiang Rai, Chiang Mai, Lamphun, Mae Hong Son, and Bangkok as pollution control zones gives local and national authorities power to act together.
This decision, announced at the Ministry of Digital Economy and Society, will let these areas step up enforcement, crack down on illegal burning, and boost air quality monitoring, especially from February to May. Bangkok’s Governor Chadchart Sittipunt said the new status will mean better coordination and tougher action.
The Pollution Control Department (PCD) has put forward a plan for 2025-2027 aimed at hitting PM2.5 sources directly. Director-General Pinsak Suraswadi highlighted the need for lasting fixes instead of quick workarounds like cloud seeding, which has shown only mixed results.
The plan features support for farmers to use machines rather than burning crop waste, along with rewards for people and companies who switch to cleaner Euro 5 and Euro 6 vehicle standards. The Clean Air Act, given initial approval by Parliament in January 2024 and under further review, is set to give local governments real legal tools to fight pollution long-term.
Tackling haze that crosses borders will also be key. Prime Minister Paetongtarn Shinawatra has promised stronger partnerships with ASEAN countries to address smoke drifting in from Myanmar, Laos, and Cambodia.
Though Thailand signed the ASEAN Agreement on Transboundary Haze Pollution in 2003, enforcement remains patchy.
Local experts, like Tippawan Prapamontol from Chiang Mai University, call for a better pollution source database so authorities can take targeted action. She points out that Thailand’s PM2.5 mix differs from that in other countries, so solutions should fit local problems.
Grassroots and Legal Pressure
People in affected areas are making their voices heard. In Mae Sai, Chiang Rai, residents took to the streets in March 2023, demanding meaningful action. The Supreme Administrative Court’s recent order followed a lawsuit by Chiang Mai resident Phumi Watcharajaroenphitpol, who cited failures to address dangerous pollution.
Civil society groups, such as the Thailand CAN network, have proposed their own Clean Air Act that focuses on sustainable local solutions and public involvement. They are pushing to let people monitor air quality themselves and report sources of pollution.
While these steps are promising, there are still big hurdles. Thailand’s official PM2.5 standards are much less strict than WHO guidelines. The updated standard in 2023 set the 24-hour PM2.5 limit at 37.5 µg/m³, double the WHO suggestion.
Slow government processes and piecemeal policies have held back progress. Critics say authorities treat the smoke as a seasonal problem, not the ongoing health emergency it is. Air pollution carries high economic costs as well, with 870 billion baht in PM2.5-related damage recorded in 2013, according to the World Bank.
Signs of progress are appearing. Court-mandated control zones now force the government to put health before tourism or farming interests. Work with NASA and the SERVIR programme is leading to new tools like the Mekong Air Quality Explorer, which blends satellite and ground readings to predict smoky days. Local innovations, such as Nion Sirimongkollertkul’s Smoke Watch system in Chiang Rai, make it easier for fire teams to respond quickly.
As another haze season nears, the creation of these new control zones offers fresh hope for cleaner air. For families like Thommamoon’s in Chiang Rai, watching their children inhale smoky air that looks like morning fog, real change can’t come soon enough.
Although the path is far from easy, with political commitment, regional teamwork, and public involvement, Thailand can start clearing away the haze that has long clouded its cities and threatened its people.
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