SmogRank / World / Japan / Niigata / September 2025

Most unhealthy days in Niigata, Japan, September 2025

11 cities in Niigata, Japan ranked by their share of unhealthy days over the 30 days. The most unhealthy days: Shibata, Japan, 0 of 30 measured days. 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.

← Shibata 0% 0.75%0
Every city in Niigata, 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. 1Shibata
    0 of 30
  2. 2Minamiuonuma
    0 of 29
  3. 3Nagaoka
    0 of 26
  4. 4Seirō
    0 of 30
  5. 5Jōetsu
    0 of 30
  6. 6Shirone
    0 of 30
  7. 7Niigata
    0 of 30
  8. 7Kameda-honchō
    0 of 30
  9. 9Sado
    0 of 30
  10. 10Niitsu-honchō
    0 of 30
  11. 10Maki
    0 of 30
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, September 2025 · All cities in Japan, September 2025 · Niigata now

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SmogRank, most polluted cities in Niigata, Japan, by unhealthy days, PM2.5, September 2025, smogrank.com/jp/region/niigata/history/2025-09?by=days (accessed 7 Oct 2026).

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