SmogRank / World / India / Bihar / September 2025

Most polluted cities in Bihar, India, September 2025

16 cities in Bihar, India ranked by their average PM2.5 over the 30 days. Worst: Aurangābād at 73.8 µg/m³, #2 of 3,052 cities in the world. Cleanest: Begusarai at 16.8. 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.

← Buxar 100% 75%0
Every city in Bihar, India 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. 1Buxar
    100%
  2. 2Bihār Sharīf
    92%
  3. 3Aurangābād
    81%
  4. 4Samāstipur
    71%
  5. 5Chāpra
    61%
  6. 6Bhāgalpur
    52%
  7. 7Mothīhāri
    42%
  8. 8Munger
    36%
  9. 9Gaya
    23%
  10. 10Patna
    13%
  11. 11Siwān
    8%
  12. 12Muzaffarpur
    0%
  13. 13Katihar
    0%
  14. 14Purnia
    0%
  15. 15Arrah
    0%
  16. 16Begusarai
    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 Bihar, India, PM2.5, September 2025, smogrank.com/in/region/bihar/history/2025-09 (accessed 6 Oct 2026).

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