SmogRank / Jeju City / Seonghwan
Jeju City vs Seonghwan: PM2.5 compared
Over the last year, Seonghwan's air was about 1.8× as polluted as Jeju City's: PM2.5 averaged 23.6 µg/m³ against 12.9, on the 340 days both cities were measured. Seonghwan had the dirtier air on 296 of those days, Jeju City on 40. Seonghwan was over the WHO's daily guideline of 15 µg/m³ on 227 of them, Jeju City on 86.
Right now
The last year, day by day
Month by month
Year by year
| Year | Jeju City | Seonghwan | Days Jeju City was worse |
|---|---|---|---|
| 2026 so far | 58 | 77 | 26 |
| 2025 | 60 | 76 | 79 |
| 2024 | 58 | 71 | 60 |
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
Jeju City
- 27 Mar 202611440.7 µg/m³
- 15 Jan 202610838.3 µg/m³
- 17 Jan 202610436.8 µg/m³
Seonghwan
- 14 Feb 202616676.7 µg/m³
- 13 Feb 202616473.4 µg/m³
- 16 Jan 202616169.8 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
Jeju City
Side by side with Ponggae-dong (the nearest), Gujranwala (the world's worst on 30 days).
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).
Use this page
SmogRank, PM2.5 daily means compared, Jeju City and Seonghwan, 10 Oct 2025 – 9 Oct 2026, smogrank.com/compare/kr-jeju-city/kr-seonghwan (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).