Bangkok air pollution rises sharply

Air pollution in Bangkok surged overnight, with PM2.5 readings above Thailand’s safety threshold in 57 monitoring areas on Friday morning, as shifting winds, a large grass fire and stagnant nighttime conditions pushed fine-dust levels higher.

The Bangkok Metropolitan Administration (BMA) Air Quality Information Centre said the city’s average PM2.5 concentration at 7am on Friday was 43.7 microgrammes per cubic metre (µg/m³), exceeding the national guideline of 37.5. The worst readings were logged in Bang Na (109.3), Thung Khru (109), Phra Khanong (107.2), Prawet (107) and Yan Nawa (106.7).

Nationwide, the Geo-Informatics and Space Technology Development Agency (Gistda) reported high to very-high fine-dust pollution in 39 provinces at 8am via its Check Dust app, with conditions particularly severe in the Central, Eastern, Western, and Northeastern regions.

Bangkok governor Chadchart Sittipunt said the capital’s spike was driven primarily by a wind shift around 10pm, which flipped from cleaner southerly flows to easterly winds that carried smoke from burning areas into the city — not by traffic, which was light at that hour.

A large grass fire in the Khu Bon area of Bang Khen district on Thursday night also worsened conditions. The blaze spread across more than 50 rai, producing heavy smoke while firefighters struggled to contain it due to a lack of nearby hydrants.

Mr Chadchart said conditions should improve as wind speeds pick up, though elevated morning readings may persist for 2–3 days because of nighttime atmospheric stagnation. He urged residents — especially vulnerable groups — to wear masks outdoors in the morning.

The governor added that the city is coordinating with neighbouring provinces to curb open burning and that PM2.5 levels are likely to ease later this month as southerly winds become established.

Residents can monitor real-time air quality on the BMA and Gistda platforms and are advised to keep windows closed during high readings, run indoor air purifiers where possible, and avoid strenuous outdoor exercise during peak hours.