Bangkok and Chiang Mai have made it into the top 50 cities worldwide for dust pollution, according to the latest data from Swiss-based IQAir.
As of 10.25am on Friday, Bangkok ranked 13th with an air quality index (AQI) of 101, despite having briefly been ranked 7th earlier in the day. Chiang Mai ranked 43rd with an AQI of 66.
Delhi, India, held the position of the most polluted city globally, with an AQI of 287. In Southeast Asia, Hanoi in Vietnam ranked 4th worst with an index of 174.
Air quality monitoring primarily focuses on major cities.
In Bangkok, the highest levels of PM2.5 were found in Nong Khaem district, recording 53.1 microgrammes per cubic metre, followed by Sathon, Bangkok Yai, Bang Bon and Phasi Charoen. The city's average level stood at 35.5µg/m³.
"When rain subsides, dust returns," Bangkok Governor Chadchart Sittipunt said on Friday on a BMA Facebook post.
City Hall is implementing measures to reduce pollution from vehicles and construction activity, particularly targeting construction trucks, Mr Chadchart said.
