SmogRank / World / North America

Most polluted cities in North America

27 of 567 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 34.4 µg/m³.

VenezuelaU.S. Virgin IslandsPuerto Rico: 1 measured cityUnited States: 478 measured citiesAnguillaCayman IslandsBermudaBritish Virgin IslandsTurks and Caicos IslandsTrinidad and TobagoSurinameSaint Vincent and the GrenadinesSaint LuciaSaint Kitts and NevisRussiaPanamaNicaraguaArubaCuracaoMexico: 26 measured citiesJamaicaHonduras: 1 measured cityHaitiGuyanaGuatemalaGrenadaFrance: 87 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 34.4 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
Honduras125.5 San Pedro Sula 25.5
Mexico2610.4 San Luis Potosí 34.4
United States4786.8 Calexico 23.1
Canada606.2 Nepean 15.1
Puerto Rico16.2 Cataño 6.2
Saint Martin14.9 Marigot 4.9

Worst cities

  1. 1San Luis PotosíSan Luis Potosí, Mexico 982.3×
  2. 2Naucalpan de JuárezMéxico, Mexico 922.1×
  3. 3Mexico CityMexico City, Mexico 821.7×
  4. 4San Pedro Sulalow-cost sensorsCortés Department, Honduras 821.7×
  5. 5Ciudad NezahualcoyotlMéxico, Mexico 791.6×
  6. 6CalexicoCalifornia, United States 771.5×
  7. 7Wheatonlow-cost sensorsIllinois, United States 751.5×
  8. 8TijuanaBaja California, Mexico 731.4×
  9. 9Los AngelesCalifornia, United States 731.4×
  10. 10San Francisco TlalcilalcalpanMéxico, Mexico 721.4×
  11. 11San Salvador TizatlalliMéxico, Mexico 721.4×
  12. 12HanfordCalifornia, United States 701.3×
  13. 13WhittierCalifornia, United States 691.2×
  14. 14FresnoCalifornia, United States 661.2×
  15. 15Granite CityIllinois, United States 661.2×
  16. 16Wake Forestlow-cost sensorsNorth Carolina, United States 661.1×
  17. 17San DiegoCalifornia, United States 661.1×
  18. 18ChattanoogaTennessee, United States 651.1×
  19. 19OregonOhio, United States 651.1×
  20. 20ComptonCalifornia, United States 641.1×
  21. 21Mission ViejoCalifornia, United States 641.1×
  22. 22Ann Arborlow-cost sensorsMichigan, United States 631.1×
  23. 23PeoriaIllinois, United States 631.0×
  24. 24LimaOhio, United States 631.0×
  25. 25CorcoranCalifornia, United States 631.0×
All cities in the world
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

Updated 2026-10-02 02:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.