SmogRank / World / United States / California / 2024

Most polluted cities in California, United States, 2024

100 cities in California, United States ranked by their average PM2.5 over the 366 days; 92 above the WHO annual guideline (5.0 µg/m³). Worst: Jurupa Valley at 14.3 µg/m³, #266 of 2,052 cities in the world. Cleanest: Solvang at 3.7. A city needs measurements on 70% of the days to be ranked.

OpenAQ's archive, where our readings come from, has almost none for one of these days. Cities in the United States and Europe have it from the EPA's and the European Environment Agency's own records of the same monitors; elsewhere a city's average is over its other days. Why.

OpenAQ's archive, where our readings come from, has almost none from the United States for March 20, 2024: cities in the United States have it from the EPA's own records of the same monitors. Why.

About 81.5K people in these 13 cities breathed unhealthy air on an average day of 2024.

Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.

← Los Angeles 53.2K 50K0
Every city in California, United States ranked for 2024 with monitors in two or more places, one column each, ranked by people breathing unhealthy air: height is people on an average day, colour its average. Point at it to read a city; tap to open it.
  1. 1Los Angeles
    53.2K
  2. 2Fresno
    13.4K
  3. 3Bakersfield
    12.3K
  4. 4Compton
    1.47K
  5. 5Merced
    906
  6. 6Carsonlow-cost sensors
    267
  7. 7Inglewoodlow-cost sensors
    0
  8. 8Torrancelow-cost sensors
    0
  9. 9La Crescenta-Montroselow-cost sensors
    0
  10. 10Santa Monicalow-cost sensors
    0
  11. 11Agouralow-cost sensors
    0
  12. 12San Jose
    0
  13. 13Banning
    0

Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.

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

All cities in the world, 2024 · All cities in United States, 2024 · California now

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SmogRank, most polluted cities in California, United States, PM2.5, 2024, smogrank.com/us/region/california/history/2024 (accessed 6 Oct 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.