SmogRank / World / United States / California / October 2023

Most polluted cities in California, United States, October 2023

104 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Imperial Beach at 14.0 µg/m³, #121 of 1,965 cities in the world. Cleanest: Gilroy at 3.3. A city needs measurements on 70% of the days to be ranked.

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.

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

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SmogRank, most polluted cities in California, United States, PM2.5, October 2023, smogrank.com/us/region/california/history/2023-10 (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.