CHIANG MAI, Thailand — After days of hazardous air that placed it among the most polluted cities in the world, Chiang Mai is showing tentative signs of improvement, though officials and environmental monitors warn that the crisis is far from over.

Recent data indicate that air quality has eased from “very unhealthy” to levels classified as “unhealthy for sensitive groups,” with fine particulate pollution — known as PM2.5 — still dominating the atmosphere. Real-time monitoring shows readings hovering in the mid-range of the unhealthy scale, underscoring persistent risks to public health.

Smoke From Seasonal Fires Continues to Blanket the Region

The deterioration in air quality stems from northern Thailand’s annual burning season, when farmers clear fields and forest fires spread across dry terrain. The period, typically lasting from January through April and peaking in March, has again produced dense haze across the region.

In early March, Chiang Mai recorded “unhealthy” pollution levels exceeding an Air Quality Index (AQI) of 150, with some districts reaching even higher readings.

Satellite and domestic monitoring agencies have also reported hundreds of fire hotspots across northern provinces, contributing to thick smoke that has reduced visibility and blanketed urban and rural areas alike.

Domestic Concern Grows as Health Effects Become Visible

Thai media and local reports describe mounting concern among residents, particularly families with children, as prolonged exposure to polluted air has led to respiratory symptoms and other health issues. In some cases, families have considered leaving the city temporarily amid fears of long-term harm.

Public health guidance has urged residents to limit outdoor activity, wear protective masks, and use air filtration indoors during peak pollution periods.

Geography and Climate Trap Pollution Over the City

Chiang Mai’s location in a mountainous basin exacerbates the crisis. Weak winds and dry seasonal conditions allow smoke to accumulate, often creating a visible haze that lingers throughout the day. Experts note that pollution can fluctuate sharply, improving briefly before deteriorating again as fires persist.

Relief Expected With Seasonal Rains — but Not Yet

While recent readings suggest a modest improvement, analysts say meaningful relief is unlikely until later in April, when the onset of the rainy season typically disperses airborne particles and clears the skies.

Until then, Chiang Mai remains in a precarious position: no longer at peak crisis levels, but still enveloped in a seasonal pollution cycle that has grown increasingly severe in recent years.

A Recurring Crisis With Long-Term Implications

The annual haze has become a defining environmental challenge for northern Thailand, with evidence suggesting that overall air quality trends have worsened over time due to continued agricultural burning and regional fires.

For now, the city’s famed mountain views remain obscured — and its residents, once again, are left waiting for the rains.