Seonghwan vs Seosan: PM2.5 compared
Over the last year, Seonghwan's air was about 1.6× as polluted as Seosan's: PM2.5 averaged 23.9 µg/m³ against 14.8, on the 332 days both cities were measured. Seonghwan had the dirtier air on 320 of those days, Seosan on 9. Seonghwan was over the WHO's daily guideline of 15 µg/m³ on 226 of them, Seosan on 120.
Right now
The last year, day by day
Month by month
Year by year
| Year | Seonghwan | Seosan | Days Seonghwan was worse |
|---|---|---|---|
| 2026 so far | 78 | 62 | 244 |
| 2025 | 76 | 63 | 330 |
| 2024 | 71 | 58 | 262 |
Means in US AQI over the days both cities were measured that year; a year shows once they share 30 such days.
Each city's worst days
Seonghwan
- 14 Feb 202616676.7 µg/m³
- 13 Feb 202616473.4 µg/m³
- 16 Jan 202616169.8 µg/m³
Seosan
- 16 Mar 202615155.9 µg/m³
- 17 Mar 202614553.3 µg/m³
- 15 Jan 202613348.3 µg/m³
Daily means in US AQI, with µg/m³ beside them, since the index stops at its top value, over the days both cities were measured in the last year. Each date opens that day's world board.
Compare either city with another
Seonghwan
Side by side with Pyeongtaek (the nearest), Kimje (South Korea's 2nd worst on 30 days), Gujranwala (the world's worst on 30 days).
Seosan
Side by side with Tangjin (the nearest), Gujranwala (the world's worst on 30 days).
Use this page
SmogRank, PM2.5 daily means compared, Seonghwan and Seosan, 10 Oct 2025 – 9 Oct 2026, smogrank.com/compare/kr-seonghwan/kr-seosan (accessed 9 Oct 2026).
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.
The same rules as every SmogRank figure: reference monitors first, and a day counts with 18 measured hours. How we measure.
Updated 2026-10-09 15:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); Love My Air (City and County of Denver), no reuse terms published (why we use them).