SmogRank / World / United States / California / May 2026

Most polluted cities in California, United States, May 2026

110 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Mecca at 16.9 µg/m³, #358 of 2,852 cities in the world. Cleanest: Sunnyvale at 1.8. 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.

← Mecca 9% 9%0
Every city in California, United States ranked for May 2026, 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. 1Mecca
    9%
  2. 2Torrancelow-cost sensors
    3%
  3. 3Jurupa Valley
    0%
  4. 4Riverside
    0%
  5. 5Whittier
    0%
  6. 6Santa Monicalow-cost sensors
    0%
  7. 7Imperial Beach
    0%
  8. 7Los Angeles
    0%
  9. 9Compton
    0%
  10. 10Fontana
    0%
  11. 11San Diego
    0%
  12. 12Anaheim
    0%
  13. 13El Cajon
    0%
  14. 14Burbank
    0%
  15. 14Long Beach
    0%
  16. 16Mission Viejo
    0%
  17. 17Visalia
    0%
  18. 18Poway
    0%
  19. 19Chula Vista
    0%
  20. 19San Luis Obispo
    0%
  21. 21Alta Sierra
    0%
  22. 21Lake Elsinore
    0%
  23. 23Simi Valley
    0%
  24. 24Santa Clarita
    0%
  25. 25Calexico
    0%
  26. 25Glendora
    0%
  27. 25Guadalupe
    0%
  28. 25King City
    0%
  29. 29Oakland
    0%
  30. 29Oceanside
    0%
  31. 31Corcoran
    0%
  32. 31Manteca
    0%
  33. 33Bakersfield
    0%
  34. 34Indio
    0%
  35. 35Santa Barbara
    0%
  36. 36El Centro
    0%
  37. 37Banning
    0%
  38. 38Clovis
    0%
  39. 38Salinas
    0%
  40. 40Oceano
    0%
  41. 41Carpinteria
    0%
  42. 42Alpine
    0%
  43. 43Temecula
    0%
  44. 44Fillmore
    0%
  45. 44Madera
    0%
  46. 44Porterville
    0%
  47. 47Fresno
    0%
  48. 47Merced
    0%
  49. 49San Francisco
    0%
  50. 50Delanolow-cost sensors
    0%
  51. 51Victorville
    0%
  52. 52Hanford
    0%
  53. 52San Jose
    0%
  54. 54Lancaster
    0%
  55. 54Santa Cruz
    0%
  56. 56Atascadero
    0%
  57. 56El Rio
    0%
  58. 56South Lake Tahoe
    0%
  59. 59Solvang
    0%
  60. 60San Leandro
    0%
  61. 60Woodland
    0%
  62. 62Thousand Oaks
    0%
  63. 63Crestline
    0%
  64. 64Ojai
    0%
  65. 65Ben Lomond
    0%
  66. 65Mammoth Lakes
    0%
  67. 67Turlock
    0%
  68. 68Gilroy
    0%
  69. 68Goletalow-cost sensors
    0%
  70. 68North Auburn
    0%
  71. 71Davis
    0%
  72. 72San Rafael
    0%
  73. 73Ridgecrest
    0%
  74. 73Sebastopol
    0%
  75. 75Yuba City
    0%
  76. 76Huron
    0%
  77. 76Crescent City
    0%
  78. 78Hollister
    0%
  79. 79Colusa
    0%
  80. 79Pleasanton
    0%
  81. 81Orcutt
    0%
  82. 81Rancho Murieta
    0%
  83. 83Galt
    0%
  84. 83Redwood City
    0%
  85. 83Roseville
    0%
  86. 83Arden-Arcade
    0%
  87. 87Stockton
    0%
  88. 87Tularelow-cost sensors
    0%
  89. 87Vallejo
    0%
  90. 90Paradise
    0%
  91. 90Sacramento
    0%
  92. 92Lincoln
    0%
  93. 92Redding
    0%
  94. 94Willows
    0%
  95. 95Concord
    0%
  96. 95Lompoc
    0%
  97. 97Big Bear City
    0%
  98. 97Ukiah
    0%
  99. 99Red Bluff
    0%
  100. 100Los Banoslow-cost sensors
    0%
  101. 101Modesto
    0%
  102. 102Chico
    0%
  103. 103Tracy
    0%
  104. 104Folsom
    0%
  105. 104Fremontlow-cost sensors
    0%
  106. 106Truckee
    0%
  107. 107Vacaville
    0%
  108. 108Yreka
    0%
  109. 109Palo Altolow-cost sensors
    0%
  110. 110Sunnyvalelow-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

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SmogRank, most polluted cities in California, United States, PM2.5, May 2026, smogrank.com/us/region/california/history/2026-05 (accessed 6 Oct 2026).

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