Over the past 24 hours, ultrafine dust levels in Bangkok and 47 other provinces in Thailand have been classified as unsafe, according to the Geo-Informatics and Space Technology Development Agency (Gistda).
As of 3 p.m., Gistda reported that PM2.5 levels—fine particulate matter measuring 2.5 micrometers or less—ranged from 38.3 to 60.7 micrograms per cubic meter (µg/m³). These elevated levels were observed across Bangkok and numerous provinces mainly in the Central Plains, Northeast, and North regions. Thailand has 76 provinces (excluding Bangkok), with a government safety threshold set at 37.5µg/m³.
The highest recorded level was in Nong Khai in the Northeast, reaching 60.7µg/m³. In Bangkok, the average PM2.5 concentration stood at 49.1µg/m³, with all 50 districts experiencing unsafe air quality. Nong Khaem district recorded the city’s highest level at 53.4µg/m³.
Other provinces with unsafe PM2.5 levels, listed in descending order, included Bung Kan, Samut Sakhon, Samut Songkhram, Maha Sarakham, Kalasin, Nakhon Pathom, Nonthaburi, Roi Et, Samut Prakan, Chon Buri, Pathum Thani, Udon Thani, Chachoengsao, Ratchaburi, Ang Thong, Ayutthaya, Sakon Nakhon, Phetchaburi, Prachin Buri, Rayong, Khon Kaen, Suphan Buri, Lop Buri, Kanchanaburi, Phetchabun, Prachuap Khiri Khan, Nakhon Ratchasima, Sing Buri, Phichit, Sa Kaeo, Nakhon Phanom, Surin, Trat, Nakhon Sawan, Uthai Thani, Buri Ram, Phitsanulok, Yasothon, Loei, Chaiyaphum, Sukhothai, Nakhon Nayok, Chai Nat, Chanthaburi, and Nong Bua Lam Phu.
Meanwhile, several southern and northern provinces experienced acceptable air quality with PM2.5 levels between 20 and 24.9µg/m³. These included Satun, Songkhla, Phuket, Krabi, Mae Hong Son, Narathiwat, Phangnga, Chiang Mai, Nakhon Si Thammarat, Chumphon, and Phatthalung.
Narong Ruangsri, the permanent secretary of the Bangkok Metropolitan Administration, warned that unsafe PM2.5 levels in the Greater Bangkok area are likely to persist until Tuesday, due to a high-pressure system moving in from China. He recommended that residents wear face masks outdoors and advised those with health issues to remain indoors.
He also noted that the Central Plains, including Greater Bangkok and parts of the Northeast, are experiencing an increase in hotspots following the end of the harvest season. Improved airflow and ventilation are expected from Wednesday to Friday to help alleviate air pollution.