SmogRank / Episodes / Thailand
Northern Thailand and Laos, 20 to 22 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 Trat Nong Chok Mukdahan Mueang Nonthaburi Suphan Buri Rayong Sing Buri Lak Si Nakhon Sawan Saphan Sung Si Maha Phot Mae Sai Chiang Mai Mae Sot Ban Houakhoua Phra Nakhon Si Ayutthaya Saraburi Nakhon Ratchasima Roi Et Chai Nat Lop Buri Chanthaburi Aranyaprathet Kamphaeng Phet Chiang Rai Phrae Phayao Loei Chaiyaphum Si Sa Ket Udon Thani Uttaradit Phichit Buri Ram Sakon Nakhon Sukhothai Ubon Ratchathani 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 Ubon Ratchathani, 18 May: 51.2 µg/m³ Ubon Ratchathani, 19 May: no reading Ubon Ratchathani, 20 May: 55.8 µg/m³, 3.4× its usual 16.2 Ubon Ratchathani, 21 May: 49.0 µg/m³, 3.2× its usual 15.2 Ubon Ratchathani, 22 May: 37.6 µg/m³, 2.6× its usual 14.5 Ubon Ratchathani, 23 May: no reading Ubon Ratchathani, 24 May: no reading Ubon Ratchathani, 25 May: no reading Pakxan Pakxan, 17 May: 24.2 µg/m³ Pakxan, 18 May: 36.7 µg/m³ Pakxan, 19 May: no reading Pakxan, 20 May: 53.5 µg/m³, 4.3× its usual 12.3 Pakxan, 21 May: 48.9 µg/m³, 4.1× its usual 11.9 Pakxan, 22 May: 41.0 µg/m³, 3.5× its usual 11.7 Pakxan, 23 May: no reading Pakxan, 24 May: no reading Pakxan, 25 May: no reading Mukdahan Mukdahan, 17 May: 45.3 µg/m³ Mukdahan, 18 May: 44.0 µg/m³ Mukdahan, 19 May: no reading Mukdahan, 20 May: 48.4 µg/m³, 2.1× its usual 22.9 Mukdahan, 21 May: 48.0 µg/m³, 2.1× its usual 22.5 Mukdahan, 22 May: 40.1 µg/m³ Mukdahan, 23 May: no reading Mukdahan, 24 May: no reading Mukdahan, 25 May: no reading Phetchabun Phetchabun, 17 May: 29.9 µg/m³ Phetchabun, 18 May: 33.4 µg/m³ Phetchabun, 19 May: no reading Phetchabun, 20 May: 44.6 µg/m³, 3.6× its usual 12.5 Phetchabun, 21 May: 41.9 µg/m³, 3.6× its usual 11.7 Phetchabun, 22 May: 36.5 µg/m³, 3.3× its usual 11.2 Phetchabun, 23 May: no reading Phetchabun, 24 May: no reading Phetchabun, 25 May: no reading Roi Et Roi Et, 17 May: 38.5 µg/m³ Roi Et, 18 May: 34.3 µg/m³ Roi Et, 19 May: no reading Roi Et, 20 May: 44.5 µg/m³, 2.4× its usual 18.8 Roi Et, 21 May: 40.2 µg/m³, 2.2× its usual 18.5 Roi Et, 22 May: 32.8 µg/m³ 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 Khon Kaen, 19 May: no reading Khon Kaen, 20 May: 42.3 µg/m³, 2.0× its usual 20.8 Khon Kaen, 21 May: 38.9 µg/m³ Khon Kaen, 22 May: 33.0 µg/m³ Khon Kaen, 23 May: no reading Khon Kaen, 24 May: no reading Khon Kaen, 25 May: no reading Nakhon Ratchasima Nakhon Ratchasima, 17 May: 39.9 µg/m³ Nakhon Ratchasima, 18 May: 35.5 µg/m³ Nakhon Ratchasima, 19 May: no reading Nakhon Ratchasima, 20 May: 40.0 µg/m³, 2.4× its usual 17.0 Nakhon Ratchasima, 21 May: 37.7 µg/m³, 2.2× its usual 16.9 Nakhon Ratchasima, 22 May: no reading Nakhon Ratchasima, 23 May: no reading Nakhon Ratchasima, 24 May: no reading Nakhon Ratchasima, 25 May: no reading Udon Thani Udon Thani, 17 May: 28.5 µg/m³ Udon Thani, 18 May: 32.5 µg/m³ Udon Thani, 19 May: no reading Udon Thani, 20 May: 39.2 µg/m³, 2.8× its usual 14.0 Udon Thani, 21 May: 41.0 µg/m³, 3.1× its usual 13.3 Udon Thani, 22 May: 37.1 µg/m³, 2.8× its usual 13.3 Udon Thani, 23 May: no reading Udon Thani, 24 May: no reading Udon Thani, 25 May: no reading Si Maha Phot Si Maha Phot, 17 May: 40.6 µg/m³ Si Maha Phot, 18 May: 36.9 µg/m³ Si Maha Phot, 19 May: no reading Si Maha Phot, 20 May: 39.2 µg/m³, 2.2× its usual 17.5 Si Maha Phot, 21 May: 36.7 µg/m³, 2.1× its usual 17.4 Si Maha Phot, 22 May: 33.5 µg/m³ Si Maha Phot, 23 May: no reading Si Maha Phot, 24 May: no reading Si Maha Phot, 25 May: no reading Si Sa Ket Si Sa Ket, 17 May: 34.6 µg/m³ Si Sa Ket, 18 May: 35.7 µg/m³ Si Sa Ket, 19 May: no reading Si Sa Ket, 20 May: 38.5 µg/m³, 3.1× its usual 12.4 Si Sa Ket, 21 May: 36.5 µg/m³, 3.2× its usual 11.4 Si Sa Ket, 22 May: 31.9 µg/m³, 2.9× its usual 11.1 Si Sa Ket, 23 May: no reading Si Sa Ket, 24 May: no reading Si Sa Ket, 25 May: no reading Uttaradit Uttaradit, 17 May: 27.0 µg/m³ Uttaradit, 18 May: 33.0 µg/m³ Uttaradit, 19 May: no reading Uttaradit, 20 May: 37.7 µg/m³, 2.5× its usual 15.0 Uttaradit, 21 May: 41.9 µg/m³, 2.9× its usual 14.7 Uttaradit, 22 May: 44.2 µg/m³, 3.1× its usual 14.4 Uttaradit, 23 May: no reading Uttaradit, 24 May: no reading Uttaradit, 25 May: no reading Sakon Nakhon Sakon Nakhon, 17 May: 29.3 µg/m³ Sakon Nakhon, 18 May: 28.4 µg/m³ Sakon Nakhon, 19 May: no reading Sakon Nakhon, 20 May: 37.3 µg/m³, 3.0× its usual 12.6 Sakon Nakhon, 21 May: 38.6 µg/m³, 3.2× its usual 12.0 Sakon Nakhon, 22 May: 35.2 µg/m³, 3.0× its usual 11.7 Sakon Nakhon, 23 May: no reading Sakon Nakhon, 24 May: no reading Sakon Nakhon, 25 May: no reading Phrae Phrae, 17 May: 26.4 µg/m³ Phrae, 18 May: 32.2 µg/m³ Phrae, 19 May: no reading Phrae, 20 May: 36.9 µg/m³, 2.6× its usual 14.2 Phrae, 21 May: 38.0 µg/m³, 2.7× its usual 14.2 Phrae, 22 May: 38.2 µg/m³, 2.8× its usual 13.8 Phrae, 23 May: no reading Phrae, 24 May: no reading Phrae, 25 May: no reading Lop Buri Lop Buri, 17 May: 34.3 µg/m³ Lop Buri, 18 May: 33.6 µg/m³ Lop Buri, 19 May: no reading Lop Buri, 20 May: 36.0 µg/m³, 2.4× its usual 14.8 Lop Buri, 21 May: 36.7 µg/m³, 2.5× its usual 14.4 Lop Buri, 22 May: 29.3 µg/m³, 2.0× its usual 14.3 Lop Buri, 23 May: no reading Lop Buri, 24 May: no reading Lop Buri, 25 May: no reading Chaiyaphum Chaiyaphum, 17 May: 30.1 µg/m³ Chaiyaphum, 18 May: 29.0 µg/m³ Chaiyaphum, 19 May: no reading Chaiyaphum, 20 May: 35.3 µg/m³, 2.9× its usual 12.1 Chaiyaphum, 21 May: 36.3 µg/m³, 3.1× its usual 11.7 Chaiyaphum, 22 May: 32.1 µg/m³, 2.8× its usual 11.5 Chaiyaphum, 23 May: no reading Chaiyaphum, 24 May: no reading Chaiyaphum, 25 May: no reading Buri Ram Buri Ram, 17 May: 34.2 µg/m³ Buri Ram, 18 May: 32.5 µg/m³ Buri Ram, 19 May: no reading Buri Ram, 20 May: 35.2 µg/m³, 3.2× its usual 11.0 Buri Ram, 21 May: 33.0 µg/m³, 3.2× its usual 10.4 Buri Ram, 22 May: 24.5 µg/m³ Buri Ram, 23 May: no reading Buri Ram, 24 May: no reading Buri Ram, 25 May: no reading Mae Sot Mae Sot, 17 May: 23.1 µg/m³ Mae Sot, 18 May: 30.8 µg/m³ Mae Sot, 19 May: no reading Mae Sot, 20 May: 35.1 µg/m³, 2.3× its usual 15.6 Mae Sot, 21 May: 30.3 µg/m³, 2.2× its usual 13.8 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 Nakhon Sawan, 18 May: 27.7 µg/m³ Nakhon Sawan, 19 May: no reading Nakhon Sawan, 20 May: 35.0 µg/m³, 2.2× its usual 15.6 Nakhon Sawan, 21 May: 34.3 µg/m³, 2.3× its usual 14.9 Nakhon Sawan, 22 May: 27.8 µg/m³ 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 Phayao, 18 May: 31.3 µg/m³ Phayao, 19 May: no reading Phayao, 20 May: 34.9 µg/m³, 2.2× its usual 16.1 Phayao, 21 May: 37.2 µg/m³, 2.3× its usual 15.9 Phayao, 22 May: 42.4 µg/m³, 2.8× its usual 15.4 Phayao, 23 May: no reading Phayao, 24 May: no reading Phayao, 25 May: no reading Saraburi Saraburi, 17 May: 33.0 µg/m³ Saraburi, 18 May: 33.0 µg/m³ Saraburi, 19 May: no reading Saraburi, 20 May: 34.9 µg/m³, 2.4× its usual 14.3 Saraburi, 21 May: 33.9 µg/m³, 2.4× its usual 14.1 Saraburi, 22 May: 29.0 µg/m³, 2.1× its usual 14.0 Saraburi, 23 May: no reading Saraburi, 24 May: no reading Saraburi, 25 May: no reading Chai Nat Chai Nat, 17 May: 25.9 µg/m³ Chai Nat, 18 May: 31.5 µg/m³ Chai Nat, 19 May: no reading Chai Nat, 20 May: 33.8 µg/m³, 2.5× its usual 13.7 Chai Nat, 21 May: 29.0 µg/m³, 2.1× its usual 13.6 Chai Nat, 22 May: 23.6 µg/m³ Chai Nat, 23 May: no reading Chai Nat, 24 May: no reading Chai Nat, 25 May: no reading Lak Si Lak Si, 17 May: 31.3 µg/m³ Lak Si, 18 May: 32.0 µg/m³ Lak Si, 19 May: no reading Lak Si, 20 May: 32.2 µg/m³, 2.1× its usual 15.5 Lak Si, 21 May: 33.0 µg/m³, 2.2× its usual 15.2 Lak Si, 22 May: 27.3 µg/m³ Lak Si, 23 May: no reading Lak Si, 24 May: no reading Lak Si, 25 May: 26.1 µg/m³ Chiang Rai Chiang Rai, 17 May: 22.4 µg/m³ Chiang Rai, 18 May: 29.2 µg/m³ Chiang Rai, 19 May: no reading Chiang Rai, 20 May: 32.0 µg/m³, 2.3× its usual 13.9 Chiang Rai, 21 May: 35.2 µg/m³, 2.6× its usual 13.6 Chiang Rai, 22 May: 35.6 µg/m³, 2.8× its usual 12.5 Chiang Rai, 23 May: no reading Chiang Rai, 24 May: no reading Chiang Rai, 25 May: no reading Loei Loei, 17 May: 24.4 µg/m³ Loei, 18 May: 33.3 µg/m³ Loei, 19 May: no reading Loei, 20 May: 31.2 µg/m³, 2.6× its usual 12.2 Loei, 21 May: 34.2 µg/m³, 2.9× its usual 11.9 Loei, 22 May: 35.5 µg/m³, 3.1× its usual 11.4 Loei, 23 May: no reading Loei, 24 May: no reading Loei, 25 May: no reading Phra Nakhon Si Ayut… Phra Nakhon Si Ayutthaya, 17 May: 32.5 µg/m³ Phra Nakhon Si Ayutthaya, 18 May: 29.8 µg/m³ Phra Nakhon Si Ayutthaya, 19 May: no reading Phra Nakhon Si Ayutthaya, 20 May: 31.1 µg/m³, 2.3× its usual 13.3 Phra Nakhon Si Ayutthaya, 21 May: 31.8 µg/m³, 2.4× its usual 13.0 Phra Nakhon Si Ayutthaya, 22 May: 29.4 µg/m³, 2.3× its usual 12.6 Phra Nakhon Si Ayutthaya, 23 May: no reading Phra Nakhon Si Ayutthaya, 24 May: no reading Phra Nakhon Si Ayutthaya, 25 May: no reading Sing Buri Sing Buri, 17 May: 31.4 µg/m³ Sing Buri, 18 May: 28.1 µg/m³ Sing Buri, 19 May: no reading Sing Buri, 20 May: 30.9 µg/m³, 2.1× its usual 14.7 Sing Buri, 21 May: 32.1 µg/m³, 2.2× its usual 14.4 Sing Buri, 22 May: 23.8 µg/m³ Sing Buri, 23 May: no reading Sing Buri, 24 May: no reading Sing Buri, 25 May: no reading Phichit Phichit, 17 May: 20.9 µg/m³ Phichit, 18 May: 26.3 µg/m³ Phichit, 19 May: no reading Phichit, 20 May: 30.7 µg/m³, 2.7× its usual 11.3 Phichit, 21 May: 32.6 µg/m³, 3.0× its usual 11.0 Phichit, 22 May: 34.8 µg/m³, 3.2× its usual 10.8 Phichit, 23 May: no reading Phichit, 24 May: no reading Phichit, 25 May: no reading Chiang Mai Chiang Mai, 17 May: 20.2 µg/m³ Chiang Mai, 18 May: 26.9 µg/m³ Chiang Mai, 19 May: no reading Chiang Mai, 20 May: 29.6 µg/m³, 2.1× its usual 14.3 Chiang Mai, 21 May: 31.4 µg/m³, 2.2× its usual 14.2 Chiang Mai, 22 May: 32.2 µg/m³, 2.3× its usual 13.8 Chiang Mai, 23 May: no reading Chiang Mai, 24 May: no reading Chiang Mai, 25 May: no reading Rayong Rayong, 17 May: 30.7 µg/m³ Rayong, 18 May: 26.3 µg/m³ Rayong, 19 May: no reading Rayong, 20 May: 29.5 µg/m³, 2.2× its usual 13.5 Rayong, 21 May: 27.4 µg/m³, 2.0× its usual 13.5 Rayong, 22 May: 29.7 µg/m³, 2.2× its usual 13.3 Rayong, 23 May: no reading Rayong, 24 May: no reading Rayong, 25 May: no reading Sukhothai Sukhothai, 17 May: 20.2 µg/m³ Sukhothai, 18 May: 24.6 µg/m³ Sukhothai, 19 May: no reading Sukhothai, 20 May: 28.6 µg/m³, 2.8× its usual 10.1 Sukhothai, 21 May: 29.3 µg/m³, 3.0× its usual 9.9 Sukhothai, 22 May: 31.8 µg/m³, 3.4× its usual 9.4 Sukhothai, 23 May: no reading Sukhothai, 24 May: no reading Sukhothai, 25 May: no reading Kamphaeng Phet Kamphaeng Phet, 17 May: 23.0 µg/m³ Kamphaeng Phet, 18 May: 26.2 µg/m³ Kamphaeng Phet, 19 May: no reading Kamphaeng Phet, 20 May: 27.5 µg/m³, 2.7× its usual 10.1 Kamphaeng Phet, 21 May: 26.7 µg/m³, 2.7× its usual 10.0 Kamphaeng Phet, 22 May: 28.4 µg/m³, 2.8× its usual 10.0 Kamphaeng Phet, 23 May: no reading Kamphaeng Phet, 24 May: no reading Kamphaeng Phet, 25 May: no reading Trat Trat, 17 May: no reading Trat, 18 May: 20.9 µg/m³ Trat, 19 May: no reading Trat, 20 May: 27.1 µg/m³, 2.1× its usual 12.8 Trat, 21 May: 24.1 µg/m³ Trat, 22 May: 20.1 µg/m³ Trat, 23 May: no reading Trat, 24 May: no reading Trat, 25 May: no reading Aranyaprathet Aranyaprathet, 17 May: 27.9 µg/m³ Aranyaprathet, 18 May: 24.1 µg/m³ Aranyaprathet, 19 May: no reading Aranyaprathet, 20 May: 26.8 µg/m³, 2.8× its usual 9.7 Aranyaprathet, 21 May: 25.8 µg/m³, 2.7× its usual 9.7 Aranyaprathet, 22 May: 21.4 µg/m³ 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 Mueang Nonthaburi, 18 May: 25.0 µg/m³ Mueang Nonthaburi, 19 May: 25.4 µg/m³ Mueang Nonthaburi, 20 May: 25.5 µg/m³, 2.0× its usual 12.6 Mueang Nonthaburi, 21 May: 27.0 µg/m³, 2.2× its usual 12.3 Mueang Nonthaburi, 22 May: 22.9 µg/m³ Mueang Nonthaburi, 23 May: 20.6 µg/m³ Mueang Nonthaburi, 24 May: 20.2 µg/m³ Mueang Nonthaburi, 25 May: no reading Suphan Buri Suphan Buri, 17 May: 34.9 µg/m³ Suphan Buri, 18 May: 29.5 µg/m³ Suphan Buri, 19 May: no reading Suphan Buri, 20 May: 26.6 µg/m³ Suphan Buri, 21 May: 29.1 µg/m³, 2.2× its usual 13.3 Suphan Buri, 22 May: 26.9 µg/m³, 2.1× its usual 13.1 Suphan Buri, 23 May: no reading Suphan Buri, 24 May: no reading Suphan Buri, 25 May: no reading Nong Chok Nong Chok, 17 May: 28.5 µg/m³ Nong Chok, 18 May: 27.0 µg/m³ Nong Chok, 19 May: no reading Nong Chok, 20 May: 27.4 µg/m³ Nong Chok, 21 May: 27.9 µg/m³, 2.0× its usual 13.8 Nong Chok, 22 May: 28.3 µg/m³, 2.1× its usual 13.4 Nong Chok, 23 May: no reading Nong Chok, 24 May: no reading Nong Chok, 25 May: 20.4 µg/m³ Chanthaburi Chanthaburi, 17 May: no reading Chanthaburi, 18 May: 21.6 µg/m³ Chanthaburi, 19 May: no reading Chanthaburi, 20 May: 24.9 µg/m³ Chanthaburi, 21 May: 27.3 µg/m³, 2.7× its usual 10.1 Chanthaburi, 22 May: 23.5 µg/m³ 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 Ban Houakhoua, 18 May: 30.2 µg/m³ Ban Houakhoua, 19 May: no reading Ban Houakhoua, 20 May: 34.8 µg/m³ Ban Houakhoua, 21 May: 39.0 µg/m³ Ban Houakhoua, 22 May: 42.9 µg/m³, 2.3× its usual 18.5 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 Mae Sai, 18 May: 34.3 µg/m³ Mae Sai, 19 May: no reading Mae Sai, 20 May: 37.5 µg/m³ Mae Sai, 21 May: 36.2 µg/m³ Mae Sai, 22 May: 41.7 µg/m³, 2.2× its usual 19.1 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 Saphan Sung, 18 May: 29.8 µg/m³ Saphan Sung, 19 May: no reading Saphan Sung, 20 May: no reading Saphan Sung, 21 May: 31.9 µg/m³ Saphan Sung, 22 May: 37.0 µg/m³, 2.2× its usual 16.6 Saphan Sung, 23 May: no reading Saphan Sung, 24 May: no reading Saphan Sung, 25 May: 29.1 µg/m³ Lamphun Lamphun, 17 May: 21.6 µg/m³ Lamphun, 18 May: 28.0 µg/m³ Lamphun, 19 May: no reading Lamphun, 20 May: 30.2 µg/m³ Lamphun, 21 May: 31.7 µg/m³ Lamphun, 22 May: 31.6 µg/m³, 2.0× its usual 15.5 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× Sakon Nakhon Sakon Nakhon, Thailand 3 21 May 12.0 3.2× Buri Ram Buriram, Thailand 2 20 May 11.0 3.2× Phichit Phichit, Thailand 3 22 May 10.8 3.2× Uttaradit Uttaradit, Thailand 3 22 May 14.4 3.1× Udon Thani Udon Thani, Thailand 3 21 May 13.3 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× Loei Loei, Thailand 3 22 May 11.4 3.1× Phayao Phayao, Thailand 3 22 May 15.4 2.8× Phrae Phrae, Thailand 3 22 May 13.8 2.8× Chiang Rai Chiang Rai, Thailand 3 22 May 12.5 2.8× Kamphaeng Phet Kamphaeng Phet, Thailand 3 22 May 10.0 2.8× Aranyaprathet Sa Kaeo, Thailand 2 20 May 9.7 2.8× Chanthaburi Chanthaburi, Thailand 1 21 May 10.1 2.7× Lop Buri Lopburi, Thailand 3 21 May 14.4 2.5× Chai Nat Chai Nat, Thailand 2 20 May 13.7 2.5× Roi Et Roi Et, Thailand 2 20 May 18.8 2.4× Nakhon Ratchasima Nakhon Ratchasima, Thailand 2 20 May 17.0 2.4× Saraburi Saraburi, Thailand 3 20 May 14.3 2.4× Phra Nakhon Si Ayutthaya Phra Nakhon Si Ayutthaya, Thailand 3 21 May 13.0 2.4× Ban Houakhoua Bokeo, Laos 1 22 May 18.5 2.3× Mae Sot Tak, Thailand 2 20 May 15.6 2.3× Chiang Mai Chiang Mai, Thailand 3 22 May 13.8 2.3× Mae Sai Chiang Rai, Thailand 1 22 May 19.1 2.2× Si Maha Phot Prachin Buri, Thailand 2 20 May 17.5 2.2× Saphan Sung Bangkok, Thailand 1 22 May 16.6 2.2× Nakhon Sawan Nakhon Sawan, Thailand 2 20 May 15.6 2.2× Lak Si Bangkok, Thailand 2 21 May 15.2 2.2× Sing Buri Sing Buri, Thailand 2 21 May 14.4 2.2× Rayong Rayong, Thailand 3 22 May 13.3 2.2× Suphan Buri Suphan Buri, Thailand 2 21 May 13.3 2.2× Mueang Nonthaburi Nonthaburi, Thailand 2 21 May 12.3 2.2× Mukdahan Mukdahan, Thailand 2 20 May 22.9 2.1× Nong Chok Bangkok, Thailand 2 22 May 13.4 2.1× Trat Trat, Thailand 1 20 May 12.8 2.1× Khon Kaen Khon Kaen, Thailand 1 20 May 20.8 2.0× Lamphun Lamphun, Thailand 1 22 May 15.5 2.0×
Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.
Against other episodes in Thailand and Laos
Number 5 of 23 episodes in Thailand and Laos since our records began, by cities reached.
Thailand and Laos, March 2025 53 Thailand, February 2024 51 Thailand, January 2025 50 Thailand and Laos, April and May 2024 45 Northern Thailand and Laos, 20 to 22 May 2023 41 Thailand, April 2023 35 Thailand and Laos, January and February 2023 34 Northern Thailand and Laos, 16 to 18 May 2023 30 Northern Thailand and Laos, October 2024 24 Thailand and Laos, November and December 2025 22 Thailand, February 2025 17 Northern Thailand, May 2023 17 Bars: cities reached; colour: the level of the episode's highest daily reading. All 23 .
Use this page SmogRank, Northern Thailand and Laos, 20 to 22 May 2023: 41 cities with PM2.5 at twice their usual or more, 20 to 22 May 2023, smogrank.com/episodes/2023-05-20-northern-thailand-and-laos (accessed 4 October 2026).
Copy citation Download top 10 (PNG)
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.
