SmogRank / World / United States / California / May 2025

Most polluted cities in California, United States, May 2025

106 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Santa Monica at 16.4 µg/m³, #355 of 2,771 cities in the world. Cleanest: Sunnyvale at 2.0. 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.

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

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SmogRank, most polluted cities in California, United States, PM2.5, May 2025, smogrank.com/us/region/california/history/2025-05 (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.