The Story
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Thailand · Tier 1
959 days · 2023–2026 · 5 sensors
Moderate confidenceSeasonal historical data — not for today's readings. For current air quality: IQAir ↗ · Methodology →
Independent modelled estimate for reference. Our data uses station sensors which may cover different years and locations. Methodology →
Berkeley Earth conversion: 22.0 µg/m³ PM2.5 ≈ 1 cigarette/day. This compares population-level mortality risk, not individual clinical outcomes. Acute vs chronic exposure differs significantly.
AQLI methodology: each 10 µg/m³ PM2.5 above WHO baseline (5.0 µg/m³) ≈ 0.98 years of life expectancy lost. Calculated from annual mean PM2.5 (long-term exposure), not annual median.
24-hour pattern from the most recent 7 days of hourly data. Dimmed arcs are unsafe for the selected activity.
This is a short-term trend view (not live minute-by-minute monitoring).
How does the air here compare to other health risks — and to peer cities?
Every day of the year, colored by PM2.5 air quality band.
The baseline view is No mask. You can switch to Surgical, KN95, or N95 to see a planning range for mask-adjusted exposure. Smoking-aware mode is optional and off by default.
Scroll through to see the numbers come alive.
Upland deforestation burning + crop residue burning across the Mekong sub-region
Affects: Feb, Mar, Apr
Heavy rainfall clears smoke and dust
Affects: Jun, Jul, Aug, Sep
Mountain topography traps cool-season pollution in the valley
Affects: Dec, Jan
Chiang Mai residents lose an estimated 2.0 years of life expectancy on average due to PM2.5 air pollution — compared to living in a city that meets WHO air quality guidelines.
Each bar shows estimated life-years lost due to that risk factor. The orange bar is Chiang Mai. Gray bars are risk comparisons.
Source: AQLI methodology — each 10 µg/m³ above the WHO 5 µg/m³ baseline ≈ 0.98 life-years lost. Population-level statistical estimates, not individual predictions. Methodology →
Tip: tap a day cell to pin details, tap outside to close.
All-years view shows the median across available years per calendar day. Individual year views show actual measured values. Methodology →
Smoking-aware mode is optional. Turn it on only if you want combined smoking + air burden estimates.
Berkeley Earth conversion: 22 µg/m³ PM2.5 ≈ 1 cigarette/day. Statistical communication tool — not a clinical diagnosis.
Planning estimate from monthly median PM2.5 values. Air-equivalent burden is additive and does not replace smoking burden.
Based on monthly median PM2.5 values. Actual exposure varies by fit, wear time, location, activity, and daily conditions. Methodology →
Section 1 of 6 · Air quality story
The WHO 2021 annual PM2.5 guideline is 5 µg/m³. Long-term exposure above this threshold is linked to cardiovascular and respiratory disease.
Section 2 of 6 · Health toll
Even if you never light one.
Berkeley Earth cigarette equivalence: 22 µg/m³ PM2.5 ≈ 1 cigarette/day. AQLI life-years: statistical population-level estimate, not individual prediction. Methodology →
Section 3 of 6 · Seasonal rhythm
Every year between February and April, Chiang Mai transforms. The mountain bowl geography that makes the city scenic—flanked by Doi Suthep to the west and highland ranges on all sides—becomes a natural smoke trap. Farmers across the wider Mekong sub-region burn fields: deforestation clearing, crop residue, slash-and-burn agriculture. The smoke drifts in and stays. March median: 54 µg/m³. Hazardous readings occurred on 16.5% of all March days in our dataset—roughly one in six days too dangerous for outdoor activity even for healthy adults. April is nearly as bad at 53 µg/m³.
= Burning Season · Bars show monthly median PM2.5
Section 4 of 6 · Seasonal risk profile
Each card shows the monthly median PM2.5 and the share of days safe for outdoor jogging.
Section 5 of 6 · The contrast
No city in our dataset shows a starker seasonal swing. September median: 6 µg/m³—among the cleanest urban air in Asia. March median: 54 µg/m³—hazardous by any standard. That is an 8.9× difference in the same city across the same year. The burning season is not a bad few days; it is a two-month annual crisis that recurs with near-certainty. The monsoon is not just relief—it is the only force powerful enough to clear the smoke from the valley. Plan your visit around it.
Section 6 of 6 · Your window
Chiang Mai's air quality is among the most polarised of any city we track. The monsoon months are genuinely exceptional. The burning season is genuinely dangerous. The window between them is narrow but predictable.
Risk levels derived from historical seasonal medians · Methodology →