Levels of ultrafine dust were rated unsafe throughout Bangkok and in 66 of the 76 provinces on Monday morning, with the worst pollution in Sing Buri.
The Geo-Informatics and Space Technology Development Agency (Gistda) reported at 9am that particulate matter 2.5 micrometres and less in diameter (PM2.5) reached harmful (red) levels in five provinces.
The highest, 85.6 microgrammes per cubic metre of air over 24 hours, was recorded in Sing Buri province, followed by 83.9µg/m³ in Nakhon Phanom, 81.5µg/m³ in Chai Nat, 80µg/m³ in Nong Bua Lam Phu and 79.6µg/m³ in Nakhon Pathom.
The government-set safe threshold is 37.5µg/m³.
Moderate and safe levels of PM2.5 were reported in Chiang Rai at 37.4µg/m³, Phuket 34.8, Chiang Mai 34, Ranong 29.2, Rayong 28.4, Mae Hong Son 27 and Nakhon Si Thammarat 26.3.
The air was rated good in Chumphon with 24.5, Surat Thani 22.7, Phangnga 21.5 and Krabi had the best air quality of 19.9µg/m³.
The other provinces registered PM2.5 levels that started to affect health, the orange level from 37.6 to 74.1µg/m³.
Unsafe levels, both orange and red, of PM2.5 blanketed all 50 districts of Bangkok. Red levels were recorded in these 34 districts:
Bangkok Yai had the highest level of 102.3µg/m³, followed by Thon Buri (100.9), Khlong San (97.1), Bang Kho Laem (94.0), Bangkok Noi (91.8), Bang Rak (91.8), Sathon (90.6), Din Daeng, (90.3), Samphanthawong (90.2), Phasicharoen (88.6), Pathumwan (88.1), Phra Nakhon (87.7), Pomprap Satruphai (87.2), Huay Khwang (86.7), Chom Thong (86.4), Rat Burana (85.8), Phra Khanong (85.6), Khlong Toey (85.3), Ratchathewi (85.2), Wathana (84.5), Chatuchak (82.5), Bang Sue (81.6) Bang Phlad (81.4), Laksi (81.3), Yannawa (80.1), Lat Phrao (79.9), Taling Chan (79.7), Wang Thonglang (79.7), Bang Khae (79.1), Nong Khaem (78.6), Suan Luang (76.6), Don Muang (76.1), Dusit (76.0) and Bang Bon (75.8).
Other districts of the capital were rated orange with PM2.5 levels ranging from 61.7 to 74.9µg/m³.
