SmogRank / World / United States / California / April 2025

Most polluted cities in California, United States, April 2025

115 cities in California, United States ranked by their average PM2.5 over the 30 days. Worst: Santa Monica at 13.8 µg/m³, #598 of 2,896 cities in the world. Cleanest: Atascadero at 2.7. 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.

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

Use this board

SmogRank, most polluted cities in California, United States, PM2.5, April 2025, smogrank.com/us/region/california/history/2025-04 (accessed 6 Oct 2026).

Download top 10 (PNG)

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.