1 April 2025 On 1 April 2026,
Chiang Mai municipality declared several areas as disaster zones following
PM2.5 levels in some districts exceeding 300 micrograms per cubic meter, almost 10 times higher than the government's safety standard.
2 April 2026 As of 2 April 2026, Chiang Mai was ranked by US AQI+ as the world's second most polluted city, with an AQI of AQI 231 (purple).
4 April 2026 On 4 April 2026, Thailand's
Ministry of Interior declared
Chiang Mai,
Lamphun, and
Phayao provinces as emergency disaster zones as a result of hazardous air quality. The declaration will allow provincial governors to disburse emergency funds. Also on 4 April, visibility in Chiang Mai at
Nakornping Hospital in
Mae Rim district decreased dramatically.
7 April 2026 On 7 April 2026, Chiang Mai continued to be ranked as having the world's worst air quality.
8 April 2026 On 8 April 2026, Third Army Area commander lieutenant general Worathep Bunya chaired an operational planning meeting in Mae Rim and subsequently joined an aerial firefighting mission in Chiang Mai. == Response ==