SmogRank / World / United States / California / July 2025

Most polluted cities in California, United States, July 2025

115 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Fontana at 13.7 µg/m³, #509 of 2,832 cities in the world. Cleanest: Atascadero at 1.2. 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.

← Compton 6% 6%0
Every city in California, United States ranked for July 2025, 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. 1Compton
    6%
  2. 2Redding
    3%
  3. 3Ukiah
    3%
  4. 4Fontana
    3%
  5. 5Glendora
    3%
  6. 6Los Angeles
    3%
  7. 7Burbank
    3%
  8. 8Santa Monicalow-cost sensors
    3%
  9. 9Anaheim
    3%
  10. 10Red Bluff
    3%
  11. 11Jurupa Valley
    0%
  12. 12Riverside
    0%
  13. 13Bakersfield
    0%
  14. 14Rio Vista
    0%
  15. 15Visalia
    0%
  16. 16Porterville
    0%
  17. 17Santa Clarita
    0%
  18. 18Agouralow-cost sensors
    0%
  19. 18Hawthornelow-cost sensors
    0%
  20. 20Corcoran
    0%
  21. 21Santa Barbara
    0%
  22. 22Imperial Beach
    0%
  23. 22Victorville
    0%
  24. 22La Crescenta-Montroselow-cost sensors
    0%
  25. 25Willows
    0%
  26. 26Carsonlow-cost sensors
    0%
  27. 26Chico
    0%
  28. 26Long Beach
    0%
  29. 29Madera
    0%
  30. 30Woodland
    0%
  31. 31Colusa
    0%
  32. 31Indio
    0%
  33. 31Inglewoodlow-cost sensors
    0%
  34. 31Torrancelow-cost sensors
    0%
  35. 35Simi Valley
    0%
  36. 36El Cajon
    0%
  37. 37Poway
    0%
  38. 38Banning
    0%
  39. 39San Diego
    0%
  40. 40Fresno
    0%
  41. 40Lomitalow-cost sensors
    0%
  42. 40North Auburn
    0%
  43. 40Paradise
    0%
  44. 44Yuba City
    0%
  45. 45Calexico
    0%
  46. 45Crestline
    0%
  47. 45Gridley
    0%
  48. 45Lake Elsinore
    0%
  49. 49Alpine
    0%
  50. 50Brawley
    0%
  51. 50Grass Valley
    0%
  52. 52Fillmore
    0%
  53. 52San Jose
    0%
  54. 52Thousand Oaks
    0%
  55. 55Turlock
    0%
  56. 56Oceanside
    0%
  57. 56Roseville
    0%
  58. 56Truckee
    0%
  59. 59Berkeley
    0%
  60. 59Lincoln
    0%
  61. 59Stockton
    0%
  62. 59Yreka
    0%
  63. 63Alta Sierra
    0%
  64. 63Huron
    0%
  65. 65Merced
    0%
  66. 66Davis
    0%
  67. 66Folsom
    0%
  68. 66Temecula
    0%
  69. 69El Rio
    0%
  70. 70Clovis
    0%
  71. 70Florinlow-cost sensors
    0%
  72. 72Galt
    0%
  73. 72Ridgecrest
    0%
  74. 72Tracy
    0%
  75. 72Arden-Arcade
    0%
  76. 76El Centro
    0%
  77. 76Lancaster
    0%
  78. 78Goletalow-cost sensors
    0%
  79. 78Ojai
    0%
  80. 80Modesto
    0%
  81. 80Richmond
    0%
  82. 82King City
    0%
  83. 82Vallejo
    0%
  84. 84Windsorlow-cost sensors
    0%
  85. 85Pleasanton
    0%
  86. 86Big Bear City
    0%
  87. 86Manteca
    0%
  88. 86Rancho Murieta
    0%
  89. 86San Leandro
    0%
  90. 90Carpinteria
    0%
  91. 91Oakland
    0%
  92. 91Palo Altolow-cost sensors
    0%
  93. 93San Luis Obispo
    0%
  94. 94Gilroy
    0%
  95. 95Martinez
    0%
  96. 96Sacramento
    0%
  97. 96South San Franciscolow-cost sensors
    0%
  98. 98Concord
    0%
  99. 98Hollister
    0%
  100. 98Salinas
    0%
  101. 101Solvang
    0%
  102. 102Guadalupe
    0%
  103. 102Lompoc
    0%
  104. 104Ben Lomond
    0%
  105. 104San Francisco
    0%
  106. 106Oceano
    0%
  107. 107Vacaville
    0%
  108. 108Livermore
    0%
  109. 109Redwood City
    0%
  110. 110San Rafael
    0%
  111. 111Sunnyvalelow-cost sensors
    0%
  112. 112Orcutt
    0%
  113. 112Santa Cruz
    0%
  114. 114Sebastopol
    0%
  115. 115Atascadero
    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 2025 · All cities in United States, July 2025 · California now

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SmogRank, most polluted cities in California, United States, PM2.5, July 2025, smogrank.com/us/region/california/history/2025-07 (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.