SmogRank / Episodes / Thailand
North-western Thailand, May 2023
For 3 days, from 20 to 22 May 2023, 41 cities in Thailand and Laos had PM2.5 at least twice their usual for the time of year. The worst reading was Ubon Ratchathani, Ubon Ratchathani, Thailand: 55.8 µg/m³ on 20 May, about 3.4× its usual 16.2.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 41 in 2 countries
Days 3 20 to 22 May 2023
Worst day 21 May 35 cities counted
Furthest above usual 4.3× Pakxan
Day by day
Play 21 May 35 cities at twice their usual or more
Tha Bo Vientiane Khlong Luang Nan Tak Sai Mai Khlong Sam Wa Khan Na Yao Bueng Kum Lat Krabang Bang Kapi Ban Khlong Prawet Bangkok Bang Na Bang Bo District Phra Pradaeng Lampang Samut Prakan Nong Khaem Bang Khun Thian Nakhon Pathom Ban Samae Dam Samut Sakhon Kanchanaburi Ban Talat Bueng Laem Chabang Ratchaburi Ban Chang Tha Yang Hua Hin Hanoi Lamphun Khon Kaen Nong Chok Mukdahan Trat Saphan Sung Mae Sai Suphan Buri Lak Si Nakhon Sawan Mueang Nonthaburi Rayong Si Maha Phot Sing Buri Ban Houakhoua Chiang Mai Mae Sot Nakhon Ratchasima Phra Nakhon Si Ayutthaya Roi Et Saraburi Chai Nat Lop Buri Chanthaburi Aranyaprathet Phrae Chiang Rai Kamphaeng Phet Phayao Chaiyaphum Loei Si Sa Ket Udon Thani Uttaradit Buri Ram Phichit Sakon Nakhon Ubon Ratchathani Sukhothai Phetchabun Pakxan 17 May 18 19 20 21 22 23 24 25 Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.
How it spread
Ubon Ratchathani Ubon Ratchathani, 17 May: 47.9 µg/m³, 3.0× usual Ubon Ratchathani, 18 May: 51.2 µg/m³, 3.2× usual Ubon Ratchathani, 19 May: no reading Ubon Ratchathani, 20 May: 55.8 µg/m³, 3.4× usual Ubon Ratchathani, 21 May: 49.0 µg/m³, 3.0× usual Ubon Ratchathani, 22 May: 37.6 µg/m³, 2.3× usual Ubon Ratchathani, 23 May: no reading Ubon Ratchathani, 24 May: no reading Ubon Ratchathani, 25 May: no reading Si Maha Phot Si Maha Phot, 17 May: 40.6 µg/m³, 2.3× usual Si Maha Phot, 18 May: 36.9 µg/m³, 2.1× usual Si Maha Phot, 19 May: no reading Si Maha Phot, 20 May: 39.2 µg/m³, 2.2× usual Si Maha Phot, 21 May: 36.7 µg/m³, 2.1× usual Si Maha Phot, 22 May: 33.5 µg/m³, 1.9× usual Si Maha Phot, 23 May: no reading Si Maha Phot, 24 May: no reading Si Maha Phot, 25 May: no reading Nakhon Ratchasima Nakhon Ratchasima, 17 May: 39.9 µg/m³, 2.3× usual Nakhon Ratchasima, 18 May: 35.5 µg/m³, 2.1× usual Nakhon Ratchasima, 19 May: no reading Nakhon Ratchasima, 20 May: 40.0 µg/m³, 2.4× usual Nakhon Ratchasima, 21 May: 37.7 µg/m³, 2.2× usual Nakhon Ratchasima, 22 May: no reading Nakhon Ratchasima, 23 May: no reading Nakhon Ratchasima, 24 May: no reading Nakhon Ratchasima, 25 May: no reading Suphan Buri Suphan Buri, 17 May: 34.9 µg/m³, 2.6× usual Suphan Buri, 18 May: 29.5 µg/m³, 2.2× usual Suphan Buri, 19 May: no reading Suphan Buri, 20 May: 26.6 µg/m³, 2.0× usual Suphan Buri, 21 May: 29.1 µg/m³, 2.2× usual Suphan Buri, 22 May: 26.9 µg/m³, 2.0× usual Suphan Buri, 23 May: no reading Suphan Buri, 24 May: no reading Suphan Buri, 25 May: no reading Si Sa Ket Si Sa Ket, 17 May: 34.6 µg/m³, 2.8× usual Si Sa Ket, 18 May: 35.7 µg/m³, 2.9× usual Si Sa Ket, 19 May: no reading Si Sa Ket, 20 May: 38.5 µg/m³, 3.1× usual Si Sa Ket, 21 May: 36.5 µg/m³, 2.9× usual Si Sa Ket, 22 May: 31.9 µg/m³, 2.6× usual Si Sa Ket, 23 May: no reading Si Sa Ket, 24 May: no reading Si Sa Ket, 25 May: no reading Lop Buri Lop Buri, 17 May: 34.3 µg/m³, 2.4× usual Lop Buri, 18 May: 33.6 µg/m³, 2.3× usual Lop Buri, 19 May: no reading Lop Buri, 20 May: 36.0 µg/m³, 2.5× usual Lop Buri, 21 May: 36.7 µg/m³, 2.5× usual Lop Buri, 22 May: 29.3 µg/m³, 2.0× usual Lop Buri, 23 May: no reading Lop Buri, 24 May: no reading Lop Buri, 25 May: no reading Buri Ram Buri Ram, 17 May: 34.2 µg/m³, 3.1× usual Buri Ram, 18 May: 32.5 µg/m³, 3.0× usual Buri Ram, 19 May: no reading Buri Ram, 20 May: 35.2 µg/m³, 3.2× usual Buri Ram, 21 May: 33.0 µg/m³, 3.0× usual Buri Ram, 22 May: 24.5 µg/m³, 2.2× usual Buri Ram, 23 May: no reading Buri Ram, 24 May: no reading Buri Ram, 25 May: no reading Saraburi Saraburi, 17 May: 33.0 µg/m³, 2.3× usual Saraburi, 18 May: 33.0 µg/m³, 2.3× usual Saraburi, 19 May: no reading Saraburi, 20 May: 34.9 µg/m³, 2.4× usual Saraburi, 21 May: 33.9 µg/m³, 2.4× usual Saraburi, 22 May: 29.0 µg/m³, 2.0× usual Saraburi, 23 May: no reading Saraburi, 24 May: no reading Saraburi, 25 May: no reading Phra Nakhon Si Ayut… Phra Nakhon Si Ayutthaya, 17 May: 32.5 µg/m³, 2.5× usual Phra Nakhon Si Ayutthaya, 18 May: 29.8 µg/m³, 2.3× usual Phra Nakhon Si Ayutthaya, 19 May: no reading Phra Nakhon Si Ayutthaya, 20 May: 31.1 µg/m³, 2.4× usual Phra Nakhon Si Ayutthaya, 21 May: 31.8 µg/m³, 2.4× usual Phra Nakhon Si Ayutthaya, 22 May: 29.4 µg/m³, 2.3× usual Phra Nakhon Si Ayutthaya, 23 May: no reading Phra Nakhon Si Ayutthaya, 24 May: no reading Phra Nakhon Si Ayutthaya, 25 May: no reading Rayong Rayong, 17 May: 30.7 µg/m³, 2.3× usual Rayong, 18 May: 26.3 µg/m³, 2.0× usual Rayong, 19 May: no reading Rayong, 20 May: 29.5 µg/m³, 2.2× usual Rayong, 21 May: 27.4 µg/m³, 2.1× usual Rayong, 22 May: 29.7 µg/m³, 2.2× usual Rayong, 23 May: no reading Rayong, 24 May: no reading Rayong, 25 May: no reading Chaiyaphum Chaiyaphum, 17 May: 30.1 µg/m³, 2.6× usual Chaiyaphum, 18 May: 29.0 µg/m³, 2.5× usual Chaiyaphum, 19 May: no reading Chaiyaphum, 20 May: 35.3 µg/m³, 3.0× usual Chaiyaphum, 21 May: 36.3 µg/m³, 3.1× usual Chaiyaphum, 22 May: 32.1 µg/m³, 2.7× usual Chaiyaphum, 23 May: no reading Chaiyaphum, 24 May: no reading Chaiyaphum, 25 May: no reading Phetchabun Phetchabun, 17 May: 29.9 µg/m³, 2.4× usual Phetchabun, 18 May: 33.4 µg/m³, 2.7× usual Phetchabun, 19 May: no reading Phetchabun, 20 May: 44.6 µg/m³, 3.6× usual Phetchabun, 21 May: 41.9 µg/m³, 3.4× usual Phetchabun, 22 May: 36.5 µg/m³, 2.9× usual Phetchabun, 23 May: no reading Phetchabun, 24 May: no reading Phetchabun, 25 May: no reading Sakon Nakhon Sakon Nakhon, 17 May: 29.3 µg/m³, 2.4× usual Sakon Nakhon, 18 May: 28.4 µg/m³, 2.4× usual Sakon Nakhon, 19 May: no reading Sakon Nakhon, 20 May: 37.3 µg/m³, 3.1× usual Sakon Nakhon, 21 May: 38.6 µg/m³, 3.2× usual Sakon Nakhon, 22 May: 35.2 µg/m³, 2.9× usual Sakon Nakhon, 23 May: no reading Sakon Nakhon, 24 May: no reading Sakon Nakhon, 25 May: no reading Aranyaprathet Aranyaprathet, 17 May: 27.9 µg/m³, 2.9× usual Aranyaprathet, 18 May: 24.1 µg/m³, 2.5× usual Aranyaprathet, 19 May: no reading Aranyaprathet, 20 May: 26.8 µg/m³, 2.8× usual Aranyaprathet, 21 May: 25.8 µg/m³, 2.7× usual Aranyaprathet, 22 May: 21.4 µg/m³, 2.2× usual Aranyaprathet, 23 May: no reading Aranyaprathet, 24 May: no reading Aranyaprathet, 25 May: no reading Mueang Nonthaburi Mueang Nonthaburi, 17 May: 27.7 µg/m³, 2.3× usual Mueang Nonthaburi, 18 May: 25.0 µg/m³, 2.0× usual Mueang Nonthaburi, 19 May: 25.4 µg/m³, 2.1× usual Mueang Nonthaburi, 20 May: 25.5 µg/m³, 2.1× usual Mueang Nonthaburi, 21 May: 27.0 µg/m³, 2.2× usual Mueang Nonthaburi, 22 May: 22.9 µg/m³, 1.9× usual Mueang Nonthaburi, 23 May: 20.6 µg/m³, 1.7× usual Mueang Nonthaburi, 24 May: 20.2 µg/m³, 1.6× usual Mueang Nonthaburi, 25 May: no reading Pakxan Pakxan, 17 May: 24.2 µg/m³, 2.0× usual Pakxan, 18 May: 36.7 µg/m³, 3.0× usual Pakxan, 19 May: no reading Pakxan, 20 May: 53.5 µg/m³, 4.3× usual Pakxan, 21 May: 48.9 µg/m³, 4.0× usual Pakxan, 22 May: 41.0 µg/m³, 3.3× usual Pakxan, 23 May: no reading Pakxan, 24 May: no reading Pakxan, 25 May: no reading Loei Loei, 17 May: 24.4 µg/m³, 2.1× usual Loei, 18 May: 33.3 µg/m³, 2.9× usual Loei, 19 May: no reading Loei, 20 May: 31.2 µg/m³, 2.7× usual Loei, 21 May: 34.2 µg/m³, 3.0× usual Loei, 22 May: 35.5 µg/m³, 3.1× usual Loei, 23 May: no reading Loei, 24 May: no reading Loei, 25 May: no reading Uttaradit Uttaradit, 17 May: 27.0 µg/m³, 1.9× usual Uttaradit, 18 May: 33.0 µg/m³, 2.3× usual Uttaradit, 19 May: no reading Uttaradit, 20 May: 37.7 µg/m³, 2.6× usual Uttaradit, 21 May: 41.9 µg/m³, 2.9× usual Uttaradit, 22 May: 44.2 µg/m³, 3.1× usual Uttaradit, 23 May: no reading Uttaradit, 24 May: no reading Uttaradit, 25 May: no reading Udon Thani Udon Thani, 17 May: 28.5 µg/m³, 2.1× usual Udon Thani, 18 May: 32.5 µg/m³, 2.4× usual Udon Thani, 19 May: no reading Udon Thani, 20 May: 39.2 µg/m³, 2.9× usual Udon Thani, 21 May: 41.0 µg/m³, 3.1× usual Udon Thani, 22 May: 37.1 µg/m³, 2.8× usual Udon Thani, 23 May: no reading Udon Thani, 24 May: no reading Udon Thani, 25 May: no reading Phrae Phrae, 17 May: 26.4 µg/m³, 1.9× usual Phrae, 18 May: 32.2 µg/m³, 2.3× usual Phrae, 19 May: no reading Phrae, 20 May: 36.9 µg/m³, 2.7× usual Phrae, 21 May: 38.0 µg/m³, 2.8× usual Phrae, 22 May: 38.2 µg/m³, 2.8× usual Phrae, 23 May: no reading Phrae, 24 May: no reading Phrae, 25 May: no reading Chai Nat Chai Nat, 17 May: 25.9 µg/m³, 1.9× usual Chai Nat, 18 May: 31.5 µg/m³, 2.3× usual Chai Nat, 19 May: no reading Chai Nat, 20 May: 33.8 µg/m³, 2.5× usual Chai Nat, 21 May: 29.0 µg/m³, 2.1× usual Chai Nat, 22 May: 23.6 µg/m³, 1.7× usual Chai Nat, 23 May: no reading Chai Nat, 24 May: no reading Chai Nat, 25 May: no reading Phichit Phichit, 17 May: 20.9 µg/m³, 1.9× usual Phichit, 18 May: 26.3 µg/m³, 2.4× usual Phichit, 19 May: no reading Phichit, 20 May: 30.7 µg/m³, 2.8× usual Phichit, 21 May: 32.6 µg/m³, 3.0× usual Phichit, 22 May: 34.8 µg/m³, 3.2× usual Phichit, 23 May: no reading Phichit, 24 May: no reading Phichit, 25 May: no reading Kamphaeng Phet Kamphaeng Phet, 17 May: 23.0 µg/m³, 2.3× usual Kamphaeng Phet, 18 May: 26.2 µg/m³, 2.6× usual Kamphaeng Phet, 19 May: no reading Kamphaeng Phet, 20 May: 27.5 µg/m³, 2.8× usual Kamphaeng Phet, 21 May: 26.7 µg/m³, 2.7× usual Kamphaeng Phet, 22 May: 28.4 µg/m³, 2.8× usual Kamphaeng Phet, 23 May: no reading Kamphaeng Phet, 24 May: no reading Kamphaeng Phet, 25 May: no reading Mukdahan Mukdahan, 17 May: 45.3 µg/m³, 2.0× usual Mukdahan, 18 May: 44.0 µg/m³, 1.9× usual Mukdahan, 19 May: no reading Mukdahan, 20 May: 48.4 µg/m³, 2.1× usual Mukdahan, 21 May: 48.0 µg/m³, 2.1× usual Mukdahan, 22 May: 40.1 µg/m³, 1.8× usual Mukdahan, 23 May: no reading Mukdahan, 24 May: no reading Mukdahan, 25 May: no reading Roi Et Roi Et, 17 May: 38.5 µg/m³, 2.0× usual Roi Et, 18 May: 34.3 µg/m³, 1.8× usual Roi Et, 19 May: no reading Roi Et, 20 May: 44.5 µg/m³, 2.4× usual Roi Et, 21 May: 40.2 µg/m³, 2.1× usual Roi Et, 22 May: 32.8 µg/m³, 1.7× usual Roi Et, 23 May: no reading Roi Et, 24 May: no reading Roi Et, 25 May: no reading Khon Kaen Khon Kaen, 17 May: no reading Khon Kaen, 18 May: 31.3 µg/m³, 1.5× usual Khon Kaen, 19 May: no reading Khon Kaen, 20 May: 42.3 µg/m³, 2.0× usual Khon Kaen, 21 May: 38.9 µg/m³, 1.9× usual Khon Kaen, 22 May: 33.0 µg/m³, 1.6× usual Khon Kaen, 23 May: no reading Khon Kaen, 24 May: no reading Khon Kaen, 25 May: no reading Mae Sot Mae Sot, 17 May: 23.1 µg/m³, 1.5× usual Mae Sot, 18 May: 30.8 µg/m³, 2.0× usual Mae Sot, 19 May: no reading Mae Sot, 20 May: 35.1 µg/m³, 2.3× usual Mae Sot, 21 May: 30.3 µg/m³, 1.9× usual Mae Sot, 22 May: no reading Mae Sot, 23 May: no reading Mae Sot, 24 May: no reading Mae Sot, 25 May: no reading Nakhon Sawan Nakhon Sawan, 17 May: 23.6 µg/m³, 1.5× usual Nakhon Sawan, 18 May: 27.7 µg/m³, 1.8× usual Nakhon Sawan, 19 May: no reading Nakhon Sawan, 20 May: 35.0 µg/m³, 2.2× usual Nakhon Sawan, 21 May: 34.3 µg/m³, 2.2× usual Nakhon Sawan, 22 May: 27.8 µg/m³, 1.8× usual Nakhon Sawan, 23 May: no reading Nakhon Sawan, 24 May: no reading Nakhon Sawan, 25 May: no reading Phayao Phayao, 17 May: 22.5 µg/m³, 1.5× usual Phayao, 18 May: 31.3 µg/m³, 2.0× usual Phayao, 19 May: no reading Phayao, 20 May: 34.9 µg/m³, 2.3× usual Phayao, 21 May: 37.2 µg/m³, 2.4× usual Phayao, 22 May: 42.4 µg/m³, 2.8× usual Phayao, 23 May: no reading Phayao, 24 May: no reading Phayao, 25 May: no reading Lak Si Lak Si, 17 May: 31.3 µg/m³, 2.1× usual Lak Si, 18 May: 32.0 µg/m³, 2.1× usual Lak Si, 19 May: no reading Lak Si, 20 May: 32.2 µg/m³, 2.1× usual Lak Si, 21 May: 33.0 µg/m³, 2.2× usual Lak Si, 22 May: 27.3 µg/m³, 1.8× usual Lak Si, 23 May: no reading Lak Si, 24 May: no reading Lak Si, 25 May: 26.1 µg/m³, 1.7× usual Chiang Rai Chiang Rai, 17 May: 22.4 µg/m³, 1.8× usual Chiang Rai, 18 May: 29.2 µg/m³, 2.3× usual Chiang Rai, 19 May: no reading Chiang Rai, 20 May: 32.0 µg/m³, 2.6× usual Chiang Rai, 21 May: 35.2 µg/m³, 2.8× usual Chiang Rai, 22 May: 35.6 µg/m³, 2.8× usual Chiang Rai, 23 May: no reading Chiang Rai, 24 May: no reading Chiang Rai, 25 May: no reading Sing Buri Sing Buri, 17 May: 31.4 µg/m³, 2.2× usual Sing Buri, 18 May: 28.1 µg/m³, 2.0× usual Sing Buri, 19 May: no reading Sing Buri, 20 May: 30.9 µg/m³, 2.1× usual Sing Buri, 21 May: 32.1 µg/m³, 2.2× usual Sing Buri, 22 May: 23.8 µg/m³, 1.7× usual Sing Buri, 23 May: no reading Sing Buri, 24 May: no reading Sing Buri, 25 May: no reading Chiang Mai Chiang Mai, 17 May: 20.2 µg/m³, 1.5× usual Chiang Mai, 18 May: 26.9 µg/m³, 1.9× usual Chiang Mai, 19 May: no reading Chiang Mai, 20 May: 29.6 µg/m³, 2.1× usual Chiang Mai, 21 May: 31.4 µg/m³, 2.3× usual Chiang Mai, 22 May: 32.2 µg/m³, 2.3× usual Chiang Mai, 23 May: no reading Chiang Mai, 24 May: no reading Chiang Mai, 25 May: no reading Sukhothai Sukhothai, 17 May: 20.2 µg/m³, 2.1× usual Sukhothai, 18 May: 24.6 µg/m³, 2.6× usual Sukhothai, 19 May: no reading Sukhothai, 20 May: 28.6 µg/m³, 3.0× usual Sukhothai, 21 May: 29.3 µg/m³, 3.1× usual Sukhothai, 22 May: 31.8 µg/m³, 3.4× usual Sukhothai, 23 May: no reading Sukhothai, 24 May: no reading Sukhothai, 25 May: no reading Trat Trat, 17 May: no reading Trat, 18 May: 20.9 µg/m³, 1.6× usual Trat, 19 May: no reading Trat, 20 May: 27.1 µg/m³, 2.1× usual Trat, 21 May: 24.1 µg/m³, 1.9× usual Trat, 22 May: 20.1 µg/m³, 1.6× usual Trat, 23 May: no reading Trat, 24 May: no reading Trat, 25 May: no reading Nong Chok Nong Chok, 17 May: 28.5 µg/m³, 2.1× usual Nong Chok, 18 May: 27.0 µg/m³, 2.0× usual Nong Chok, 19 May: no reading Nong Chok, 20 May: 27.4 µg/m³, 2.0× usual Nong Chok, 21 May: 27.9 µg/m³, 2.1× usual Nong Chok, 22 May: 28.3 µg/m³, 2.1× usual Nong Chok, 23 May: no reading Nong Chok, 24 May: no reading Nong Chok, 25 May: 20.4 µg/m³, 1.5× usual Chanthaburi Chanthaburi, 17 May: no reading Chanthaburi, 18 May: 21.6 µg/m³, 2.1× usual Chanthaburi, 19 May: no reading Chanthaburi, 20 May: 24.9 µg/m³, 2.5× usual Chanthaburi, 21 May: 27.3 µg/m³, 2.7× usual Chanthaburi, 22 May: 23.5 µg/m³, 2.3× usual Chanthaburi, 23 May: no reading Chanthaburi, 24 May: no reading Chanthaburi, 25 May: no reading Ban Houakhoua Ban Houakhoua, 17 May: 24.1 µg/m³, 1.3× usual Ban Houakhoua, 18 May: 30.2 µg/m³, 1.6× usual Ban Houakhoua, 19 May: no reading Ban Houakhoua, 20 May: 34.8 µg/m³, 1.9× usual Ban Houakhoua, 21 May: 39.0 µg/m³, 2.1× usual Ban Houakhoua, 22 May: 42.9 µg/m³, 2.3× usual Ban Houakhoua, 23 May: no reading Ban Houakhoua, 24 May: no reading Ban Houakhoua, 25 May: no reading Mae Sai Mae Sai, 17 May: 31.1 µg/m³, 1.6× usual Mae Sai, 18 May: 34.3 µg/m³, 1.8× usual Mae Sai, 19 May: no reading Mae Sai, 20 May: 37.5 µg/m³, 2.0× usual Mae Sai, 21 May: 36.2 µg/m³, 1.9× usual Mae Sai, 22 May: 41.7 µg/m³, 2.2× usual Mae Sai, 23 May: no reading Mae Sai, 24 May: no reading Mae Sai, 25 May: no reading Saphan Sung Saphan Sung, 17 May: 32.8 µg/m³, 2.0× usual Saphan Sung, 18 May: 29.8 µg/m³, 1.8× usual Saphan Sung, 19 May: no reading Saphan Sung, 20 May: no reading Saphan Sung, 21 May: 31.9 µg/m³, 1.9× usual Saphan Sung, 22 May: 37.0 µg/m³, 2.2× usual Saphan Sung, 23 May: no reading Saphan Sung, 24 May: no reading Saphan Sung, 25 May: 29.1 µg/m³, 1.8× usual Lamphun Lamphun, 17 May: 21.6 µg/m³, 1.4× usual Lamphun, 18 May: 28.0 µg/m³, 1.8× usual Lamphun, 19 May: no reading Lamphun, 20 May: 30.2 µg/m³, 1.9× usual Lamphun, 21 May: 31.7 µg/m³, 2.0× usual Lamphun, 22 May: 31.6 µg/m³, 2.0× usual Lamphun, 23 May: no reading Lamphun, 24 May: no reading Lamphun, 25 May: no reading 17 May 18 19 20 21 22 23 24 25 Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Pakxan Bolikhamsai, Laos 3 20 May 12.3 4.3× Phetchabun Phetchabun, Thailand 3 20 May 12.5 3.6× Ubon Ratchathani Ubon Ratchathani, Thailand 3 20 May 16.2 3.4× Sukhothai Sukhothai, Thailand 3 22 May 9.4 3.4× Phichit Phichit, Thailand 3 22 May 10.8 3.2× Sakon Nakhon Sakon Nakhon, Thailand 3 21 May 12.0 3.2× Buri Ram Buriram, Thailand 2 20 May 11.0 3.2× Loei Loei, Thailand 3 22 May 11.4 3.1× Si Sa Ket Si Sa Ket, Thailand 3 20 May 12.4 3.1× Chaiyaphum Chaiyaphum, Thailand 3 21 May 11.7 3.1× Udon Thani Udon Thani, Thailand 3 21 May 13.3 3.1× Uttaradit Uttaradit, Thailand 3 22 May 14.4 3.1× Aranyaprathet Sa Kaeo, Thailand 2 17 May 9.7 2.9× Chiang Rai Chiang Rai, Thailand 3 22 May 12.5 2.8× Kamphaeng Phet Kamphaeng Phet, Thailand 3 22 May 10.0 2.8× Phrae Phrae, Thailand 3 22 May 13.8 2.8× Phayao Phayao, Thailand 3 22 May 15.4 2.8× Chanthaburi Chanthaburi, Thailand 1 21 May 10.1 2.7× Suphan Buri Suphan Buri, Thailand 2 17 May 13.3 2.6× Lop Buri Lopburi, Thailand 3 21 May 14.4 2.5× Phra Nakhon Si Ayutthaya Phra Nakhon Si Ayutthaya, Thailand 3 17 May 13.0 2.5× Chai Nat Chai Nat, Thailand 2 20 May 13.7 2.5× Saraburi Saraburi, Thailand 3 20 May 14.3 2.4× Roi Et Roi Et, Thailand 2 20 May 18.8 2.4× Nakhon Ratchasima Nakhon Ratchasima, Thailand 2 20 May 17.0 2.4× Chiang Mai Chiang Mai, Thailand 3 22 May 13.8 2.3× Si Maha Phot Prachin Buri, Thailand 2 17 May 17.5 2.3× Ban Houakhoua Bokeo, Laos 1 22 May 18.5 2.3× Rayong Rayong, Thailand 3 17 May 13.3 2.3× Mueang Nonthaburi Nonthaburi, Thailand 2 17 May 12.3 2.3× Mae Sot Tak, Thailand 2 20 May 15.6 2.3× Nakhon Sawan Nakhon Sawan, Thailand 2 20 May 15.6 2.2× Sing Buri Sing Buri, Thailand 2 21 May 14.4 2.2× Saphan Sung Bangkok, Thailand 1 22 May 16.6 2.2× Mae Sai Chiang Rai, Thailand 1 22 May 19.1 2.2× Lak Si Bangkok, Thailand 2 21 May 15.2 2.2× Nong Chok Bangkok, Thailand 2 17 May 13.4 2.1× Trat Trat, Thailand 1 20 May 12.8 2.1× Mukdahan Mukdahan, Thailand 2 20 May 22.9 2.1× Lamphun Lamphun, Thailand 1 21 May 15.5 2.0× Khon Kaen Khon Kaen, Thailand 1 20 May 20.8 2.0×
Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.
Against other episodes in Thailand and Laos
Number 5 of 24 episodes in Thailand and Laos since our records began, by cities reached.
Central Thailand, March 2025 53 Western Thailand, February 2024 51 Central Thailand, January 2025 50 North-western Thailand, April and May 2024 45 North-western Thailand, May 2023 41 Western Thailand, April 2023 35 Western Thailand and Laos, January and February 2023 34 North-western Thailand, May 2023 30 North-eastern Thailand, October 2024 24 Northern Thailand, November and December 2025 22 Western Thailand, February 2025 17 North-western Thailand, May 2023 17 Bars: cities reached; colour: the level of the episode's highest daily reading. All 24 .
Use this page SmogRank, North-western Thailand, May 2023: 41 cities with PM2.5 at twice their usual or more, 20 to 22 May 2023, smogrank.com/episodes/2023-05-north-western-thailand-3 (accessed 3 October 2026).
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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms .
An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes . Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.
