CHIANG MAI – The dry season haze has returned to northern Thailand, and Chiang Mai’s air quality is slipping fast. Public health officials say PM2.5 pollution has climbed above safe limits in several districts. As a result, both locals and tourists face higher health risks, especially as forest fires and seasonal smoke increase.
Every year, the region enters the well-known burning season, which usually runs from February through May. In 2026, it started strong. Recent readings show PM2.5 jumping in many areas. Some southern districts, including Hot, reported levels up to 71.3 µg/m³.
That sits well above Thailand’s 24-hour standard of 37.5 µg/m³. Across Chiang Mai, monitors often show moderate to unhealthy air, commonly between 37 and 71 µg/m³. Smoke from field burning, forest hotspots, and trapped pollution during temperature inversions all play a role.
Chiang Mai and nearby Chiang Rai deal with this cycle year after year. Still, health officials say this season feels heavier. They warn that today’s exposure affects daily life now and can also add up over time.
Health Officials Ask People to Stay Alert
Health teams want the public to take the haze seriously. In recent advisories, a spokesperson said PM2.5 can enter deep into the lungs and even reach the bloodstream. Because of that, they urge everyone, especially people at higher risk, to take protective steps right away.
Recommended actions include:
- Cut back on outdoor time, especially hard exercise, when the haze looks thickest (often mornings and late afternoons).
- Wear an N95 mask or a similar respirator when you go outside, and PM2.5 levels stay high.
- Keep windows closed at home and use an air purifier if you have one.
- Check live air quality updates through apps like Air4Thai or IQAir.
- Get medical help if symptoms show up, such as an ongoing cough, shortness of breath, chest tightness, or eye irritation.
Some groups face greater danger during high PM2.5 days. This includes kids, older adults, pregnant women, and people with asthma, heart disease, or diabetes. Officials also stress that early treatment can lower the chance of bigger problems.
What PM2.5 Can Do to Your Health
PM2.5 refers to tiny particles smaller than 2.5 micrometers. Because they are so small, they can move deep into the airways and pass into the blood. This can trigger inflammation and stress in the body. In the short term, many people experience symptoms that interrupt work, school, and sleep.
Common short-term effects include:
- Coughing and sneezing
- Skin irritation and rashes
- Burning, red, or watery eyes
- Sore throat and stuffy nose
These issues can start within hours, and they often worsen with long periods outside.
Over the long run, repeated exposure can lead to more serious health outcomes. Research links ongoing PM2.5 exposure with conditions such as:
- Heart and blood vessel problems: Irregular heartbeat, heart failure, stroke, and high blood pressure
- Lung and breathing disease: Asthma flare-ups, COPD, and a higher risk of lung cancer
- Other body-wide effects: Lower lung function, weaker immune response, and possible impacts on brain health
Because Chiang Mai sees these spikes every year, the total exposure adds up. Health workers say that makes seasonal haze even more concerning for people who already have health conditions.
Why the Haze Peaks From February Through May
Northern Thailand’s weather and terrain make it easy for smoke to build up. The season brings dry air and little rain. At the same time, temperature inversions can trap pollution near the ground. Several sources feed the problem:
- Burning crop waste in fields
- Forest fires, with recent reports citing 182 hotspots in the Chiang Mai area
- Smoke drifting in from nearby regions
- Traffic and industrial pollution in cities
This year, fires in southern districts have pushed air quality into the red, unhealthy range in places like Hot. Winds then carry smoke toward the city, where it can collect and linger downtown.
In many years, PM2.5 reaches its highest levels in March and April. At times, haze can reduce visibility enough to disrupt flights. So far in 2026, daily readings have shifted between moderate and unhealthy. Still, without rain or stronger winds, officials expect more bad days ahead.
What Officials and Communities Are Doing
Local agencies continue to track PM2.5 through monitoring stations across the province. In past seasons, authorities have also closed some national parks and outdoor areas to limit exposure. At the same time, they keep pushing for stricter enforcement against open burning and more support for cleaner options.
Residents can help by reporting illegal fires and joining local clean-air efforts. During high-risk periods, health departments also hand out free masks and run public awareness campaigns.
As the haze season continues, officials keep the message simple: protect yourself early. PM2.5 levels may rise and fall day to day, but the overall trend is moving up, so daily precautions still matter.
