Chiang Mai ranked 5th among global cities with worst air quality Monday

Chiang Mai ranked fifth among global cities with the worst air quality on Monday, recording an AQI of 166, while Lampang and Mae Hong Son had even higher levels.

Chiang Mai was reported by the IQAir website as the fifth city with the worst air quality among international cities on Monday morning.

At 7:50 am, IQAir recorded Chiang Mai’s Air Quality Index (AQI) at 166, ranking it fifth among international cities with the poorest air quality. It followed Kathmandu, Nepal (237 AQI), Delhi, India (183 AQI), Yangon, Myanmar (170 AQI), and Lahore, Pakistan (166 AQI).

IQAir (iqair.com) is an online platform operated by the Swiss technology company IQAir, which specialises in air quality monitoring. The website and its AirVisual platform use a colour-coded system to represent air quality levels based on the AQI.While Chiang Mai was the international city in Thailand with the worst air quality on Monday morning, the website also reported that two non-international districts had even poorer air quality: Wiang Nua district in Lampang, with an AQI of 242, and Tambon Mae Hi in Mae Hong Son, with an AQI of 227.

Chiang Mai’s air quality fell into the red zone, while Lampang and Mae Hong Son were in the purple zone.
IQAir categorises air quality using the following colour-coded system:


Green (AQI 0-50): Good
Yellow (AQI 51-100): Moderate
Orange (AQI 101-150): Unhealthy for Sensitive Groups
Red (AQI 151-200): Unhealthy
Purple (AQI 201-300): Very Unhealthy
Maroon/Dark Red (AQI 300+): Hazardous

(2025/03/31-00:00)