SmogRank / World / North America

Most polluted cities in North America

29 of 565 measured cities in 6 countries were above the WHO 24-hour guideline over the last 24 hours. The worst was San Luis Potosí, Mexico, at 34.5 µg/m³.

VenezuelaU.S. Virgin IslandsPuerto Rico: 1 measured cityUnited States: 475 measured citiesAnguillaCayman IslandsBermudaBritish Virgin IslandsTurks and Caicos IslandsTrinidad and TobagoSurinameSaint Vincent and the GrenadinesSaint LuciaSaint Kitts and NevisRussiaPanamaNicaraguaArubaCuracaoMexico: 27 measured citiesJamaicaHonduras: 1 measured cityHaitiGuyanaGuatemalaGrenadaFrance: 81 measured citiesSaint Pierre and MiquelonSaint Martin: 1 measured cityEl SalvadorDominican RepublicDominicaGreenlandCubaCosta RicaColombiaCanada: 60 measured citiesBrazil: 6 measured citiesBelizeBarbadosBahamasAntigua and BarbudaSint Maarten
Each dot is a measured city, coloured by its PM2.5 over the last 24 hours; tap a country to open it.
← San Luis Potosí 34.5 WHO 24-hour guideline
Every measured city in North America, one column each, worst on the left and cleanest on the right. Point at it to read a city; tap to open it.

Countries

CountryCitiesMedianCities by bandWorst city
Honduras126.2 San Pedro Sula 26.2
Mexico2710.6 San Luis Potosí 34.5
United States4757.0 Calexico 22.1
Puerto Rico16.3 Cataño 6.3
Canada606.2 Nepean 16.1
Saint Martin14.7 Marigot 4.7

Worst cities

  1. 1San Luis PotosíSan Luis Potosí, Mexico 34.52.3×
  2. 2Naucalpan de JuárezMéxico, Mexico 30.22.0×
  3. 3Mexico CityMexico City, Mexico 27.91.9×
  4. 4San Pedro Sulalow-cost sensorsCortés Department, Honduras 26.21.7×
  5. 5Ciudad NezahualcoyotlMéxico, Mexico 25.01.7×
  6. 6CalexicoCalifornia, United States 22.11.5×
  7. 7TijuanaBaja California, Mexico 21.01.4×
  8. 8San Salvador TizatlalliMéxico, Mexico 21.01.4×
  9. 9Jurupa ValleyCalifornia, United States 20.81.4×
  10. 10Los AngelesCalifornia, United States 20.21.3×
  11. 11Wheatonlow-cost sensorsIllinois, United States 20.11.3×
  12. 12San Francisco TlalcilalcalpanMéxico, Mexico 19.91.3×
  13. 13HanfordCalifornia, United States 19.41.3×
  14. 14WhittierCalifornia, United States 18.01.2×
  15. 15Ann Arborlow-cost sensorsMichigan, United States 17.81.2×
  16. 16Wake Forestlow-cost sensorsNorth Carolina, United States 17.41.2×
  17. 17FresnoCalifornia, United States 17.31.2×
  18. 18OregonOhio, United States 16.91.1×
  19. 19San DiegoCalifornia, United States 16.91.1×
  20. 20ChattanoogaTennessee, United States 16.41.1×
  21. 21Mission ViejoCalifornia, United States 16.31.1×
  22. 22CorcoranCalifornia, United States 16.11.1×
  23. 23Nepeanlow-cost sensorsOntario, Canada 16.11.1×
  24. 24Granite CityIllinois, United States 15.91.1×
  25. 25LimaOhio, United States 15.81.1×
All cities in the world
Good0–9.0
Moderate9.1–35.4
Sensitive groups35.5–55.4
Unhealthy55.5–125.4
Very unhealthy125.5–225.4
Hazardous225.5+

PM2.5 in µg/m³, coloured by the US EPA's PM2.5 categories. Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Updated 2026-10-02 04:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors in µg/m³.