SmogRank / World / North America

Most polluted cities in North America

32 of 562 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: 473 measured citiesAnguillaCayman IslandsBermudaBritish Virgin IslandsTurks and Caicos IslandsTrinidad and TobagoSurinameSaint Vincent and the GrenadinesSaint LuciaSaint Kitts and NevisRussiaPanamaNicaraguaArubaCuracaoMexico: 26 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 µg/m³ 30 µg/m³15 WHO 24-hour guideline0
Every measured city in North America, 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.

Countries

CountryCitiesMedianCities by bandWorst city
Honduras127.3 San Pedro Sula 27.3
Mexico2611.1 San Luis Potosí 34.5
United States4737.0 Calexico 22.3
Puerto Rico16.4 Cataño 6.4
Canada606.1 Nepean 16.9
Saint Martin14.6 Marigot 4.6

Worst cities

  1. 1San Luis PotosíSan Luis Potosí, Mexico 982.3×
  2. 2Naucalpan de JuárezMéxico, Mexico 902.0×
  3. 3Mexico CityMexico City, Mexico 871.9×
  4. 4San Pedro Sulalow-cost sensorsCortés Department, Honduras 851.8×
  5. 5Ciudad NezahualcoyotlMéxico, Mexico 811.7×
  6. 6CalexicoCalifornia, United States 761.5×
  7. 7San Salvador TizatlalliMéxico, Mexico 741.4×
  8. 8TijuanaBaja California, Mexico 731.4×
  9. 9Jurupa ValleyCalifornia, United States 731.4×
  10. 10San Francisco TlalcilalcalpanMéxico, Mexico 721.4×
  11. 11Los AngelesCalifornia, United States 711.3×
  12. 12HanfordCalifornia, United States 701.3×
  13. 13Wheatonlow-cost sensorsIllinois, United States 671.2×
  14. 14Ann Arborlow-cost sensorsMichigan, United States 671.2×
  15. 15Wake Forestlow-cost sensorsNorth Carolina, United States 671.2×
  16. 16WhittierCalifornia, United States 671.2×
  17. 17FresnoCalifornia, United States 661.2×
  18. 18OregonOhio, United States 661.2×
  19. 19San DiegoCalifornia, United States 661.1×
  20. 20Nepeanlow-cost sensorsOntario, Canada 661.1×
  21. 21CorcoranCalifornia, United States 651.1×
  22. 22MexicaliBaja California, Mexico 651.1×
  23. 23Mission ViejoCalifornia, United States 651.1×
  24. 24PortsmouthOhio, United States 651.1×
  25. 25ChattanoogaTennessee, United States 641.1×
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 06:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.