SmogRank / World / South Korea / Chungcheongnam-do / October 2025

Most polluted cities in Chungcheongnam-do, South Korea, October 2025

14 cities in Chungcheongnam-do, South Korea ranked by their average PM2.5 over the 31 days. Worst: Seonghwan at 14.6 µg/m³, #356 of 2,564 cities in the world. Cleanest: Gongju at 7.4. A city needs measurements on 70% of the days to be ranked.

About 13.3K people in these 12 cities breathed unhealthy air on an average day of October 2025.

Ranked by people: each city's population times its share of unhealthy days, those with a daily mean over 35.4 µg/m³ (US AQI 101+). That is how many people living there breathed unhealthy air on an average day. Only cities measured at 2 or more places at least 3 km apart are ranked: one monitor shouldn't speak for a whole city. Population is the city itself, not its wider metro area.

← Asan 3.15K 3K0
Every city in Chungcheongnam-do, South Korea ranked for October 2025 with monitors in two or more places, one column each, ranked by people breathing unhealthy air: height is people on an average day, colour its average. Point at it to read a city; tap to open it.
  1. 1Asan
    3.15K
  2. 2Boryeong
    3.04K
  3. 3Hongseong
    2.88K
  4. 4Seonghwan
    1.89K
  5. 5Yesan
    1.27K
  6. 6Tangjin
    1.06K
  7. 7Cheonan
    0
  8. 8Yŏnmu
    0
  9. 9Taesal-li
    0
  10. 9Nonsan
    0
  11. 11Seosan
    0
  12. 12Gongju
    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

All cities in the world, October 2025 · All cities in South Korea, October 2025 · Chungcheongnam-do now

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SmogRank, most polluted cities in Chungcheongnam-do, South Korea, PM2.5, October 2025, smogrank.com/kr/region/chungcheongnam-do/history/2025-10 (accessed 7 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.