CHIANG RAI – Thailand’s Pollution Control Department (PCD) warns PM2.5 pollution has risen above safe limits and reached red-alert levels in several northern provinces. The worst-affected areas include Lamphun, Mae Hong Son, Chiang Rai, Lampang, Nan, Phrae, Phayao, and Chiang Mai.
Officials are asking people to protect themselves during the haze. If you need to go outside, wear a proper mask and keep outdoor time as short as possible. People should also follow advice from the Ministry of Public Health while the pollution remains severe. Real-time air quality updates are available on the Air4Thai website, Air4Thai.pcd.go.th, and through the Air4Thai mobile app.
This yearly spike usually happens from February to April. Dry weather, temperature inversions, and widespread burning all make the problem worse. Recent hotspot reports show thousands of fires, most of them in forest areas, which have pushed PM2.5 levels higher across the upper North.
PM2.5 Levels and Why Red Alerts Matter
PM2.5 means very fine dust particles that are smaller than 2.5 micrometers. Because they are so tiny, they can travel deep into the lungs and even enter the bloodstream. Thailand’s 24-hour safety limit is 37.5 µg/m³. When levels move into the red category, the health risk rises sharply, especially for people who are more sensitive to air pollution.
In reports from early March 2026, PM2.5 readings in northern provinces ranged from 18.4 to more than 112 µg/m³. Some locations in Lampang, Lamphun, and Phrae recorded peaks close to, or above, 90 to 100 µg/m³. During some of those days, Chiang Mai also ranked among the most polluted cities in the world, with AQI readings above 150.
These readings trigger red warnings on air quality indexes. As a result, residents are told to take action right away to reduce exposure.
Northern Provinces Seeing the Worst PM2.5 Pollution
The PCD has identified eight provinces where PM2.5 levels have moved well beyond the standard and into the red zone:
- Lamphun: This province often reports very high levels, with places like Ban Klang reaching around 94 µg/m³.
- Mae Hong Son: Forest fires have hit this area hard and added heavily to the regional haze.
- Chiang Rai: Border districts often face a mix of local smoke and haze drifting in from nearby areas.
- Lampang: Some reports show the province with the highest number of hotspots and sharp PM2.5 increases.
- Nan: Burning in farm and forest areas has pushed pollution levels higher.
- Phrae: Places such as Na Chak subdistrict have posted strong PM2.5 readings.
- Phayao: Monitoring stations have shown air quality shifting from orange to red.
- Chiang Mai: This major city continues to struggle, with stations like Chang Phueak showing unhealthy levels during haze peaks.
Other northern provinces have also seen poor air quality. Still, these eight have repeatedly recorded the most serious warnings.
Provinces and high-risk areas:
- Lamphun, Ban Klang and nearby districts
- Mae Hong Son, Mueang district and forest zones
- Chiang Rai, Mae Sai and Wiang districts
- Lampang, Phra Bat subdistrict
- Nan, farm areas and highland zones
- Phrae, Na Chak subdistrict
- Phayao, areas near stations showing health impacts
- Chiang Mai, Chang Phueak and Chiang Dao districts
Why PM2.5 Pollution Gets So Bad in Northern Thailand
The biggest cause is biomass burning during the dry season. This includes:
- Burning crop leftovers in fields, such as rice, maize, and sugarcane
- Forest fires and clearing undergrowth
- Other burning in wooded and mountain areas
Hotspot numbers have climbed fast, and forest areas account for most of the detections. In one update from early March, authorities recorded nearly 2,000 hotspots in a single day. Lampang, Phrae, Lamphun, and Chiang Mai often rank among the provinces with the most fire activity.
Several other factors also make the haze worse:
- Still air and temperature inversions trap smoke close to the ground
- Smoke drifts in from nearby regions and across borders
- Combustion byproducts form secondary aerosols that add to PM2.5 levels
Authorities have introduced zero open-burning policies, mostly aimed at farm fires. Even so, forest fires and other non-crop burning still play a major role. Some studies show that biomass sources account for more than 60% of PM2.5 during haze season in the North. In some cases, non-crop burning contributes more than crop residue burning.
Health Effects of High PM2.5 Exposure
Short-term exposure to heavy PM2.5 pollution can cause eye irritation, coughing, sore throat, breathing trouble, and lower lung function. If exposure continues over time, the risk of serious health problems goes up. These include lung disease, heart disease, stroke, and other long-term conditions.
Some groups face a higher risk than others. That includes children, older adults, pregnant women, and people who already have heart or lung problems. In Chiang Mai, for example, both residents and visitors have reported more breathing issues, eye irritation, and skin symptoms during heavy haze periods than during cleaner months.
Cutting down time outdoors can reduce those symptoms a lot. Health officials also link bad air days to more hospital visits for respiratory illness, conjunctivitis, and dermatitis.
Protection Steps Recommended by the Ministry of Public Health
When PM2.5 reaches orange or red levels, health officials recommend these steps:
- Stay indoors as much as you can, especially during the worst hours of the day
- Wear a proper mask such as an N95 or another PM2.5-filtering mask if you need to go outside
- Avoid heavy outdoor activity like exercise, because it makes you breathe in more polluted air
- Watch for symptoms like coughing, breathing trouble, eye irritation, nausea, or dizziness, and get medical care if they get worse
- Take extra care of high-risk groups, including children, older adults, pregnant people, and anyone with chronic illness
- Improve indoor air quality by keeping windows closed and using a HEPA air purifier if possible
The Ministry of Public Health also asks people to keep checking updates and follow local health advice. Some studies show that limiting outdoor activity can lower symptom risk by as much as 69%.
Basic self-protection tips:
- Check the Air4Thai app or website before leaving home
- Go outside only for essential trips
- Wear an N95 or PM2.5 mask correctly
- Drink enough water and avoid activities that add more smoke to the air
- Keep medicine ready and plan indoor options for sensitive family members
How Residents Can Track PM2.5 Levels
People can follow the air quality situation in real time through several free tools:
- Website: Air4Thai.pcd.go.th, with hourly and daily readings from PCD stations across Thailand
- Mobile app: Air4Thai, available on Google Play and the App Store, with maps, graphs, alerts, and 7-day history
- Other sources: IQAir and local provincial updates for added context
These tools show PM2.5 readings in µg/m³, color-coded health levels, and in some cases forecasts as well. Categories usually range from green for good air to yellow for moderate, orange for air that is starting to affect health, and red for unhealthy conditions. Users can also zoom in on specific provinces and districts to check readings from nearby stations.
Wider Efforts to Reduce the Haze Problem
Local and national agencies are trying to reduce the haze through burning bans, better hotspot tracking with satellite data from GISTDA, and support for farming methods that do not rely on slash-and-burn practices. There are also calls for stronger cooperation with neighboring countries, because some of the smoke travels across borders.
At the community level, people are running awareness campaigns, providing air purifiers to schools, and allowing work-from-home options during severe pollution periods. Over the long term, officials continue to focus on sustainable farming, better forest management, and lower overall biomass burning.
Residents can also help by reporting illegal burning and supporting zero-burning efforts during the dry season.
Northern Thailand’s PM2.5 crisis shows how serious the annual haze problem has become. By following PCD alerts, wearing the right mask, and checking Air4Thai updates, people can lower their personal risk while officials continue broader control efforts.
Authorities say shared action matters. Cutting unnecessary burning and following health advice can help reduce the burden on communities in Lamphun, Mae Hong Son, Chiang Rai, Lampang, Nan, Phrae, Phayao, Chiang Mai, and other nearby provinces.
