SmogRank / World / Japan / Ibaraki / September 2025

Most polluted cities in Ibaraki, Japan, September 2025

19 cities in Ibaraki, Japan ranked by their average PM2.5 over the 30 days. Worst: Tsuchiura at 11.4 µg/m³, #487 of 3,052 cities in the world. Cleanest: Koga at 6.7. 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.

← Tsuchiura 0% 0.75%0
Every city in Ibaraki, Japan ranked for September 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. 1Tsuchiura
    0%
  2. 2Kamisu
    0%
  3. 3Shimo-tsuma
    0%
  4. 4Naka
    0%
  5. 5Chikusei
    0%
  6. 6Jōsō
    0%
  7. 7Kashima-shi
    0%
  8. 7Bandō
    0%
  9. 9Hokota
    0%
  10. 10Kasama
    0%
  11. 11Toride
    0%
  12. 12Hitachi-Naka
    0%
  13. 12Inashiki
    0%
  14. 14Ishioka
    0%
  15. 15Mito
    0%
  16. 16Hitachi
    0%
  17. 16Hitachiomiya
    0%
  18. 18Kitaibaraki
    0%
  19. 19Koga
    0%
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 Ibaraki, Japan, PM2.5, September 2025, smogrank.com/jp/region/ibaraki/history/2025-09 (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.