SmogRank / World / United States / California / July 2023

Most polluted cities in California, United States, July 2023

104 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Fontana at 19.4 µg/m³, #73 of 1,375 cities in the world. Cleanest: Atascadero at 3.4. 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.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Indio 14% 10%0
Every city in California, United States ranked for July 2023, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Indio
    14%
  2. 2Glendora
    7%
  3. 3Banning
    6%
  4. 4Oceano
    3%
  5. 5Fontana
    3%
  6. 6Riverside
    3%
  7. 7Jurupa Valley
    3%
  8. 8El Centro
    3%
  9. 9Anaheim
    3%
  10. 10Los Angeles
    0%
  11. 11Compton
    0%
  12. 12Burbank
    0%
  13. 13Santa Clarita
    0%
  14. 14Bakersfield
    0%
  15. 15Brawley
    0%
  16. 15Visalia
    0%
  17. 15Rio Vista
    0%
  18. 18Hanford
    0%
  19. 19Long Beach
    0%
  20. 19Paradise
    0%
  21. 21Victorville
    0%
  22. 21La Crescenta-Montroselow-cost sensors
    0%
  23. 23Carsonlow-cost sensors
    0%
  24. 23Hawthornelow-cost sensors
    0%
  25. 25Ukiah
    0%
  26. 26Porterville
    0%
  27. 27Chula Vista
    0%
  28. 27El Cajon
    0%
  29. 27Fresno
    0%
  30. 27Torrancelow-cost sensors
    0%
  31. 27Yuba City
    0%
  32. 32Calexico
    0%
  33. 32Turlock
    0%
  34. 34Inglewoodlow-cost sensors
    0%
  35. 34Santa Monicalow-cost sensors
    0%
  36. 36Lake Elsinore
    0%
  37. 36Madera
    0%
  38. 38Lomitalow-cost sensors
    0%
  39. 39Colusa
    0%
  40. 39San Diego
    0%
  41. 41Agouralow-cost sensors
    0%
  42. 41Simi Valley
    0%
  43. 43Fillmore
    0%
  44. 43Santa Barbara
    0%
  45. 43Thousand Oaks
    0%
  46. 46Modesto
    0%
  47. 46Poway
    0%
  48. 46Redwood City
    0%
  49. 49Clovis
    0%
  50. 50Willows
    0%
  51. 50Red Bluff
    0%
  52. 52Alpine
    0%
  53. 52Crestline
    0%
  54. 52Gridley
    0%
  55. 52San Jose
    0%
  56. 56Chico
    0%
  57. 56Oceanside
    0%
  58. 56Stockton
    0%
  59. 59Sacramento
    0%
  60. 60Merced
    0%
  61. 60Roseville
    0%
  62. 62Lincoln
    0%
  63. 62Richmond
    0%
  64. 64Corcoran
    0%
  65. 65Davis
    0%
  66. 66Salinas
    0%
  67. 67Mammoth Lakes
    0%
  68. 67Oakland
    0%
  69. 69Concord
    0%
  70. 70Huron
    0%
  71. 70Livermore
    0%
  72. 72Manteca
    0%
  73. 72Redding
    0%
  74. 72Arden-Arcade
    0%
  75. 75Galt
    0%
  76. 76Yreka
    0%
  77. 77North Auburn
    0%
  78. 77Truckee
    0%
  79. 79San Leandro
    0%
  80. 79Anderson
    0%
  81. 81Alta Sierra
    0%
  82. 82King City
    0%
  83. 82Rancho Murieta
    0%
  84. 84Folsom
    0%
  85. 85Grass Valley
    0%
  86. 86Ojai
    0%
  87. 86San Francisco
    0%
  88. 86Tracy
    0%
  89. 89Big Bear City
    0%
  90. 89Solvang
    0%
  91. 91Ben Lomond
    0%
  92. 92Vacaville
    0%
  93. 92Crescent City
    0%
  94. 94San Rafael
    0%
  95. 95Hollister
    0%
  96. 95Lancaster
    0%
  97. 97Lompoc
    0%
  98. 98Gilroy
    0%
  99. 99San Luis Obispo
    0%
  100. 100Sebastopol
    0%
  101. 101Santa Cruz
    0%
  102. 102Guadalupe
    0%
  103. 103Orcutt
    0%
  104. 104Atascadero
    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, July 2023 · All cities in United States, July 2023 · California now

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SmogRank, most polluted cities in California, United States, PM2.5, July 2023, smogrank.com/us/region/california/history/2023-07 (accessed 7 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.