SmogRank / World / North America

Most polluted cities in North America

33 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 34.5 µg/m³.

VenezuelaU.S. Virgin IslandsPuerto Rico: 1 measured cityUnited States: 477 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
Honduras126.6 San Pedro Sula 26.6
Mexico2710.7 San Luis Potosí 34.5
United States4777.1 Calexico 22.3
Puerto Rico16.3 Cataño 6.3
Canada606.1 Nepean 16.6
Saint Martin14.7 Marigot 4.7

Worst cities

  1. 1San Luis PotosíSan Luis Potosí, Mexico 502.3×
  2. 2Naucalpan de JuárezMéxico, Mexico 432.0×
  3. 3Mexico CityMexico City, Mexico 411.9×
  4. 4San Pedro Sulalow-cost sensorsCortés Department, Honduras 381.8×
  5. 5Ciudad NezahualcoyotlMéxico, Mexico 361.7×
  6. 6CalexicoCalifornia, United States 321.5×
  7. 7San Salvador TizatlalliMéxico, Mexico 311.4×
  8. 8TijuanaBaja California, Mexico 311.4×
  9. 9Jurupa ValleyCalifornia, United States 301.4×
  10. 10Los AngelesCalifornia, United States 291.3×
  11. 11San Francisco TlalcilalcalpanMéxico, Mexico 291.3×
  12. 12HanfordCalifornia, United States 281.3×
  13. 13Wheatonlow-cost sensorsIllinois, United States 281.3×
  14. 14Ann Arborlow-cost sensorsMichigan, United States 261.2×
  15. 15WhittierCalifornia, United States 261.2×
  16. 16Wake Forestlow-cost sensorsNorth Carolina, United States 251.2×
  17. 17FresnoCalifornia, United States 251.2×
  18. 18OregonOhio, United States 251.1×
  19. 19San DiegoCalifornia, United States 251.1×
  20. 20Nepeanlow-cost sensorsOntario, Canada 241.1×
  21. 21Mission ViejoCalifornia, United States 241.1×
  22. 22ChattanoogaTennessee, United States 241.1×
  23. 23CorcoranCalifornia, United States 241.1×
  24. 24PortsmouthOhio, United States 241.1×
  25. 25LimaOhio, United States 231.1×
All cities in the world
Excellent0–50
Good51–100
Lightly polluted101–150
Moderately polluted151–200
Heavily polluted201–300
Severely polluted301+

China's Air Quality Index (HJ 633-2012), PM2.5 individual index. Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Updated 2026-10-02 05:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the China AQI PM2.5 sub-index.