CHIANG RAI– People across northern Thailand woke up Sunday to another morning of dense, smoky air. As the annual burning season peaks in late March 2026, PM2.5levels have climbed into unhealthy ranges in both Chiang Rai and Chiang Mai.
Local monitoring stations show AQIreadings in the Unhealthy category, roughly 150 to 180, for much of the past week. In some areas, the numbers have gone even higher. Between March 28 and 29, Chiang Rai’s Mueang district recorded about 158 to 164 AQI. Chiang Mai stayed near 152 to 158, and some places saw worse readings earlier in the week.
That level of pollution can affect everyone, not only people with existing health issues. Fine PM2.5particles, which are smaller than 2.5 microns, are filling the air due to crop burning, forest fires, and still weather that traps smoke in the valleys.
Air Quality Snapshot, March 29, 2026
- Chiang Rai: AQI is about 158 to 176, ranging from Unhealthy to Very Unhealthy. PM2.5 often rises above 60 to 90 μg/m³.
- Chiang Mai: AQI has recently ranged from about 152 to over 220 on the worst days, with PM2.5 as the main pollutant. At times this month, the city ranked among the 10 most polluted in the world.
- Regional trend: Other northern provinces, including Lampang, Phrae, and Nan, are also dealing with poor air. Hotspots linked to agricultural burning remain active despite government action.
The weather is making things worse. Dry heat and light winds create temperature inversions, so the smoke stays low instead of clearing out. At the same time, daytime highs around 35 to 39°C make being outside even more uncomfortable.
Why Air Pollution Peaks Every March
After harvest, many farmers burn rice stubble and other crop waste to clear fields. Along with forest fires, that practice sends a large amount of smoke into the air. Burning in nearby border areas also adds to the problem.
March is usually the worst month. Historical records show PM2.5 levels rising sharply from February into March, and unhealthy air can last for weeks. In past years, Chiang Rai has posted March averages above 100 μg/m³, which is far beyond safe limits.
This year is following that familiar pattern. While some earlier days were less severe, late March brought heavier haze. Residents and expats have reported itchy eyes, sore throats, and frequent sneezing. One cyclist riding in the hills near Chiang Mai said the morning air felt especially heavy.
Officials are tracking hotspots by satellite and urging people to reduce open burning. Still, fires scattered across mountainous areas are hard to control. The season often starts to ease when rain arrives in April or May, but in drier years, relief can take longer.
Health Risks and Who Should Be Most Careful
Health agencies issue stronger warnings once the AQI moves above 100 to 150. Breathing polluted air for long periods can irritate the lungs and eyes. It can also make asthma, heart disease, and allergies worse.
- Children and older adults face a greater risk of breathing problems.
- People with lung or heart conditions should cut back on outdoor time.
- Pregnant women and anyone with a chronic illness need to be extra careful.
These tiny PM2.5 particles can travel deep into the lungs and even enter the bloodstream. In the short term, people may notice coughing, shortness of breath, or burning eyes. Over time, repeated exposure is linked to more serious health issues, although one haze season alone is unlikely to cause lasting harm in otherwise healthy adults.
Doctors in Chiang Rai and Chiang Mai often see more haze-related cases at this time of year. Hospitals urge people to watch symptoms closely and get medical help if breathing becomes difficult.
How to Protect Yourself From PM2.5
You don’t need to stay indoors every minute, but a few simple steps can lower your exposure.
- Check the AQI every day: Use apps like Air4Thai, IQAir, or aqicn.org before you go out. Try to plan outdoor activities when levels dip, often later in the day or after the wind picks up.
- Wear the right mask: Choose an N95 or KN95 mask when you’re outside. Standard surgical masks block less fine dust. A snug fit matters, so make sure the mask seals well.
- Stay inside when you can: Keep windows and doors closed on bad air days. Run a HEPA air purifier at home if possible. Also, skip outdoor workouts and heavy physical work.
- Spend less time outdoors: Shorten walks, avoid hard exercise, and keep children’s playtime inside. Shopping malls and air-conditioned indoor spaces can offer a break from the smoke.
- Take care of your body: Drink plenty of water, eat fruits and vegetables, and get enough sleep. If you have a medical condition, keep your medicine close and follow your doctor’s advice.
Families in Chiang Rai say small habits help. One local parent shared that they run air purifiers all day and only step outside early, when the haze sometimes lifts a little. Tourists should pack masks and check air reports before visiting temples or heading into the hills.
What Authorities Are Doing, and What May Happen Next
Officials across northern Thailand are working together in 17 provinces. They are trying to reduce hotspots, apply burn bans where they can, and promote other ways to manage crop waste, such as composting. The Third Army Area and local teams are also helping with fire control.
Still, progress is slow. Many farmers still depend on burning because it’s quick and cheap. Public campaigns are trying to shift those habits, but that change won’t happen overnight.
Over the next several days, conditions may go up and down through early April. Some forecasts suggest air quality will stay unhealthy, although wind or brief showers could bring short breaks. In most years, the clearest improvement comes later, when monsoon rains return.
For now, residents are adjusting to masks, purifiers, and more time indoors. New arrivals quickly learn to check air quality apps every day.
Northern Thailand is beautiful for most of the year, but the March haze is hard on everyone. On March 29, 2026, Chiang Rai and Chiang Mai remain in the Unhealthy range. The situation is serious, but people can manage the risk by staying alert and taking basic precautions.
Follow updates from Thailand’s Pollution Control Department. Use trusted AQI apps. Local advice can also help, especially when conditions change fast.
If you develop a persistent cough, chest tightness, or strong irritation, see a doctor right away. Healthy adults may handle short exposure better than others, but no one should brush off repeated warnings.
This year’s burning season shows how closely farming, weather, and public health are tied together. Small daily choices, along with broader action, can reduce the impact until cleaner air returns.
