SmogRank / History / May 21, 2023

Most polluted cities on May 21, 2023

1,537 cities ranked by their average PM2.5 over the day; the worst was Fort McMurray, Canada, at 343.5 µg/m³. Each city's own local calendar day.

Bad-air episodes during May 21, 2023. All episodes.

← Fort McMurray 343.5 µg/m³ 300 µg/m³15 WHO 24-hour guideline
Every city ranked for May 21, 2023, one column each, worst on the left and cleanest on the right; height is PM2.5 in µg/m³. Point at it to read a city; tap to open it.
  1. 1Fort McMurrayAlberta, Canada
    500+22.9×
  2. 2EdmontonAlberta, Canada
    39618.2×
  3. 3St. AlbertAlberta, Canada
    27013.0×
  4. 4Red DeerAlberta, Canada
    25111.7×
  5. 5Grande PrairieAlberta, Canada
    2098.9×
  6. 6BloemfonteinFree State, South Africa
    2038.5×
  7. 7Lahorelow-cost sensorsPunjab, Pakistan
    1967.9×
  8. 7Sherwood ParkAlberta, Canada
    1967.9×
  9. 9Fort St. JohnBritish Columbia, Canada
    1867.0×
  10. 10CoyhaiqueAysén, Chile
    1867.0×
  11. 11AirdrieAlberta, Canada
    1755.9×
  12. 12Swift CurrentSaskatchewan, Canada
    1705.5×
  13. 13Medicine HatAlberta, Canada
    1645.0×
  14. 14DelhiDelhi, India
    1604.5×
  15. 15JakartaJakarta, Indonesia
    1594.5×
  16. 16ShenyangLiaoning, China
    1564.2×
  17. 17RancaguaO'Higgins Region, Chile
    1533.9×
  18. 18Puente AltoSantiago Metropolitan, Chile
    1523.8×
  19. 19Dhakalow-cost sensorsDhaka Division, Bangladesh
    1513.7×
  20. 20ThembisaGauteng, South Africa
    1473.6×
  21. 21CuricóMaule Region, Chile
    1413.4×
  22. 22LinaresMaule Region, Chile
    1393.4×
  23. 23Ubon RatchathaniUbon Ratchathani, Thailand
    1343.3×
  24. 23GilletteWyoming, United States
    1343.3×
  25. 25PakxanBolikhamsai, Laos
    1343.3×
  26. 26Peshawarlow-cost sensorsKhyber Pakhtunkhwa, Pakistan
    1323.2×
  27. 27HyderabadTelangana, India
    1323.2×
  28. 27MukdahanMukdahan, Thailand
    1323.2×
  29. 29CalgaryAlberta, Canada
    1323.2×
  30. 30AntananarivoAnalamanga, Madagascar
    1293.1×
  31. 31RengoO'Higgins Region, Chile
    1283.1×
  32. 32NanNan, Thailand
    1273.1×
  33. 33SantiagoSantiago Metropolitan, Chile
    1273.1×
  34. 34BaghdadBaghdad, Iraq
    1243.0×
  35. 35Ga-RankuwaNorth West, South Africa
    1233.0×
  36. 36Puerto AysénAysén, Chile
    1222.9×
  37. 37NacimientoBiobio, Chile
    1202.9×
  38. 38TalaganteSantiago Metropolitan, Chile
    1182.8×
  39. 39UttaraditUttaradit, Thailand
    1172.8×
  40. 39PhetchabunPhetchabun, Thailand
    1172.8×
  41. 41KigaliKigali, Rwanda
    1162.8×
  42. 42Udon ThaniUdon Thani, Thailand
    1152.7×
  43. 43SheridanWyoming, United States
    1132.7×
  44. 44Roi EtRoi Et, Thailand
    1132.7×
  45. 45QuillotaValparaiso, Chile
    1102.6×
  46. 45IrapuatoGuanajuato, Mexico
    1102.6×
  47. 47CuranilahueBiobio, Chile
    1102.6×
  48. 48Ban HouakhouaBokeo, Laos
    1102.6×
  49. 49Khon KaenKhon Kaen, Thailand
    1092.6×
  50. 50Kathmandulow-cost sensorsBagmati Province, Nepal
    1092.6×
  51. 51Sakon NakhonSakon Nakhon, Thailand
    1092.6×
  52. 51ChillánÑuble, Chile
    1092.6×
  53. 53PhraePhrae, Thailand
    1072.5×
  54. 54Nakhon RatchasimaNakhon Ratchasima, Thailand
    1062.5×
  55. 55PhayaoPhayao, Thailand
    1052.5×
  56. 56San CarlosÑuble, Chile
    1042.5×
  57. 57Si Maha PhotPrachin Buri, Thailand
    1042.4×
  58. 57Lop BuriLopburi, Thailand
    1042.4×
  59. 59Si Sa KetSi Sa Ket, Thailand
    1032.4×
  60. 60Islamabadlow-cost sensorsIslamabad, Pakistan
    1032.4×
  61. 61ChaiyaphumChaiyaphum, Thailand
    1032.4×
  62. 62Mae SaiChiang Rai, Thailand
    1032.4×
  63. 63BrakpanGauteng, South Africa
    1012.4×
  64. 64Chiang RaiChiang Rai, Thailand
    1002.3×
  65. 65Puerto VarasLos Lagos Region, Chile
    992.3×
  66. 66OsornoLos Lagos Region, Chile
    992.3×
  67. 67SasolburgFree State, South Africa
    992.3×
  68. 68Nakhon SawanNakhon Sawan, Thailand
    982.3×
  69. 69LampangLampang, Thailand
    982.3×
  70. 69LoeiLoei, Thailand
    982.3×
  71. 71SaraburiSaraburi, Thailand
    972.3×
  72. 72Khlong Sam WaBangkok, Thailand
    972.3×
  73. 73TalcaMaule Region, Chile
    962.2×
  74. 74Buri RamBuriram, Thailand
    962.2×
  75. 74Lak SiBangkok, Thailand
    962.2×
  76. 76PhichitPhichit, Thailand
    952.2×
  77. 77Bang NaBangkok, Thailand
    952.2×
  78. 78Nong KhaemBangkok, Thailand
    942.1×
  79. 78Great FallsMontana, United States
    942.1×
  80. 80Sing BuriSing Buri, Thailand
    942.1×
  81. 81CelayaGuanajuato, Mexico
    932.1×
  82. 81Saphan SungBangkok, Thailand
    932.1×
  83. 83Phra Nakhon Si AyutthayaPhra Nakhon Si Ayutthaya, Thailand
    932.1×
  84. 84LamphunLamphun, Thailand
    932.1×
  85. 85Chiang MaiChiang Mai, Thailand
    932.1×
  86. 86Khan Na YaoBangkok, Thailand
    922.1×
  87. 87Los ÁngelesBiobio, Chile
    912.1×
  88. 88DushanbeDushanbe, Tajikistan
    912.0×
  89. 88Viña del MarValparaiso, Chile
    912.0×
  90. 90Mae SotTak, Thailand
    902.0×
  91. 91QuinteroValparaiso, Chile
    902.0×
  92. 92CoquimboCoquimbo Region, Chile
    902.0×
  93. 93SukhothaiSukhothai, Thailand
    892.0×
  94. 94Suphan BuriSuphan Buri, Thailand
    881.9×
  95. 95Chai NatChai Nat, Thailand
    881.9×
  96. 96JacksonMississippi, United States
    881.9×
  97. 96Bueng KumBangkok, Thailand
    881.9×
  98. 98Bang KapiBangkok, Thailand
    881.9×
  99. 98Ban Talat BuengChon Buri, Thailand
    881.9×
  100. 100HualquiBiobio, Chile
    871.9×
  101. 100Lat KrabangBangkok, Thailand
    871.9×
  102. 102Khlong LuangPathum Thani, Thailand
    871.9×
  103. 102ConcónValparaiso, Chile
    871.9×
  104. 104KnoxvilleTennessee, United States
    871.9×
  105. 105TemucoAraucania, Chile
    871.9×
  106. 106Nong ChokBangkok, Thailand
    861.9×
  107. 107RabinalBaja Verapaz, Guatemala
    861.8×
  108. 107Guatemala CityGuatemala, Guatemala
    861.8×
  109. 109East RidgeTennessee, United States
    851.8×
  110. 110BangkokBangkok, Thailand
    851.8×
  111. 111RayongRayong, Thailand
    851.8×
  112. 111BillingsMontana, United States
    851.8×
  113. 113ChanthaburiChanthaburi, Thailand
    851.8×
  114. 114RatchaburiRatchaburi, Thailand
    851.8×
  115. 115HernandoMississippi, United States
    851.8×
  116. 116Mueang NonthaburiNonthaburi, Thailand
    841.8×
  117. 116La SerenaCoquimbo Region, Chile
    841.8×
  118. 118Kamphaeng PhetKamphaeng Phet, Thailand
    841.8×
  119. 118ChattanoogaTennessee, United States
    841.8×
  120. 120Phra PradaengSamut Prakan, Thailand
    831.8×
  121. 120Nakhon PathomNakhon Pathom, Thailand
    831.8×
  122. 122BurnsvilleMinnesota, United States
    831.7×
  123. 123Sai MaiBangkok, Thailand
    821.7×
  124. 124AranyaprathetSa Kaeo, Thailand
    821.7×
  125. 125GuangzhouGuangdong, China
    821.7×
  126. 126TakTak, Thailand
    821.7×
  127. 126Bang Bo DistrictSamut Prakan, Thailand
    821.7×
  128. 128Laem ChabangChon Buri, Thailand
    811.7×
  129. 128HuntsvilleAlabama, United States
    811.7×
  130. 130ChennaiTamil Nadu, India
    811.7×
  131. 131LethbridgeAlberta, Canada
    811.7×
  132. 132MinneapolisMinnesota, United States
    801.7×
  133. 133Rapid CitySouth Dakota, United States
    801.7×
  134. 134BirminghamAlabama, United States
    801.6×
  135. 135TratTrat, Thailand
    791.6×
  136. 135Ban ChangRayong, Thailand
    791.6×
  137. 137AntofagastaAntofagasta, Chile
    791.6×
  138. 138Addis AbabaAddis Ababa, Ethiopia
    791.6×
  139. 139ColomboWestern Province, Sri Lanka
    781.6×
  140. 140SenicaTrnava Region, Slovakia
    781.6×
  141. 140Ciudad JuárezChihuahua, Mexico
    781.6×
  142. 142AustinTexas, United States
    781.6×
  143. 143Ban Khlong PrawetBangkok, Thailand
    781.6×
  144. 143Český TěšínMoravian-Silesian Region, Czechia
    781.6×
  145. 145TexarkanaTexas, United States
    781.6×
  146. 146Samut SakhonSamut Sakhon, Thailand
    771.6×
  147. 146KłodzkoLower Silesia, Poland
    771.6×
  148. 146CauquenesMaule Region, Chile
    771.6×
  149. 146SaskatoonSaskatchewan, Canada
    771.6×
  150. 150MaryvilleTennessee, United States
    771.5×
  151. 151ShakopeeMinnesota, United States
    771.5×
  152. 152YangonYangon, Myanmar
    771.5×
  153. 152HobbsNew Mexico, United States
    771.5×
  154. 154Puerto MonttLos Lagos Region, Chile
    771.5×
  155. 155WatertownSouth Dakota, United States
    751.5×
  156. 156GreeleyColorado, United States
    751.5×
  157. 157Frýdek-MístekMoravian-Silesian Region, Czechia
    751.5×
  158. 158Live OakTexas, United States
    751.5×
  159. 159Jelenia GóraLower Silesia, Poland
    751.5×
  160. 160TalcahuanoBiobio, Chile
    741.4×
  161. 161TocopillaAntofagasta, Chile
    741.4×
  162. 162La UniónLos Ríos Region, Chile
    741.4×
  163. 162RoanokeVirginia, United States
    741.4×
  164. 164StilfonteinNorth West, South Africa
    741.4×
  165. 164Saint PaulMinnesota, United States
    741.4×
  166. 166TrnavaTrnava Region, Slovakia
    741.4×
  167. 167KadaňÚstí nad Labem Region, Czechia
    741.4×
  168. 167HueytownAlabama, United States
    741.4×
  169. 167WaterlooIowa, United States
    741.4×
  170. 170OpavaMoravian-Silesian Region, Czechia
    731.4×
  171. 171OstravaMoravian-Silesian Region, Czechia
    731.4×
  172. 171Alto HospicioTarapacá, Chile
    731.4×
  173. 171CheyenneWyoming, United States
    731.4×
  174. 174MostÚstí nad Labem Region, Czechia
    731.4×
  175. 174CoronelBiobio, Chile
    731.4×
  176. 174Winston-SalemNorth Carolina, United States
    731.4×
  177. 177Tha YangPhetchaburi, Thailand
    721.4×
  178. 178NauenBrandenburg, Germany
    721.4×
  179. 178HavířovMoravian-Silesian Region, Czechia
    721.4×
  180. 178BartlettTennessee, United States
    721.4×
  181. 181KladnoCentral Bohemia, Czechia
    721.4×
  182. 181ValdiviaLos Ríos Region, Chile
    721.4×
  183. 181WittenbergSaxony-Anhalt, Germany
    721.4×
  184. 184DěčínÚstí nad Labem Region, Czechia
    711.3×
  185. 184PeoriaIllinois, United States
    711.3×
  186. 186HelenaMontana, United States
    711.3×
  187. 187PrešovPrešov Region, Slovakia
    711.3×
  188. 187KrefeldNorth Rhine-Westphalia, Germany
    711.3×
  189. 187LotaBiobio, Chile
    711.3×
  190. 187Idaho FallsIdaho, United States
    711.3×
  191. 191NordhausenThuringia, Germany
    711.3×
  192. 191La Crescenta-Montroselow-cost sensorsCalifornia, United States
    711.3×
  193. 193Hua HinPrachuap Khiri Khan, Thailand
    701.3×
  194. 193HalberstadtSaxony-Anhalt, Germany
    701.3×
  195. 193AnkenyIowa, United States
    701.3×
  196. 196KöthenSaxony-Anhalt, Germany
    701.3×
  197. 196KoblenzRheinland-Pfalz, Germany
    701.3×
  198. 196ZnojmoSouth Moravian, Czechia
    701.3×
  199. 196BohumínMoravian-Silesian Region, Czechia
    701.3×
  200. 200Dún LaoghaireLeinster, Ireland
    701.3×

Top 200 of 1,537 shown.

Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

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SmogRank, most polluted cities, PM2.5, May 21, 2023, smogrank.com/history/2023-05-21 (accessed 2 Oct 2026).

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