Chiang Mai has reached a critical state this morning as PM 2.5 dust levels continue to rise, topping the list as the world's most polluted major city.
On 30 March 2026, reporters noted that the IQAir website's live ranking at 07:00 showed Chiang Mai, Thailand, as the world's most polluted major city, with an AQI of 205, severely impacting everyone.
The top five most polluted major cities worldwide are:
Rank 1: Chiang Mai Municipality, Thailand, with an AQI of 205 (purple level).
Rank 2: Yangon, Myanmar, with an AQI of 186 (red level).
Rank 3: Delhi, India, with an AQI of 175 (red level).
Rank 4: Kampala, Uganda, with an AQI of 160 (red level).
Rank 5: Hanoi, Vietnam, with an AQI of 158 (red level).
The AQI is divided into six levels as follows:
- Green 0-50: Good level.
- Yellow 51-100: Moderate level.
- Orange 101-150: Unhealthy for sensitive groups or those with weak health.
- Red 151-200: Unhealthy for everyone.
- Purple 201-300: Very unhealthy for everyone.
- Brown 301 and above: Hazardous level.