Incheon vs Seonghwan: PM2.5 compared

Over the last year, Seonghwan's air was 24% more polluted than Incheon's: PM2.5 averaged 23.2 µg/m³ against 18.7, on the 354 days both cities were measured. Seonghwan had the dirtier air on 301 of those days, Incheon on 51. Seonghwan was over the WHO's daily guideline of 15 µg/m³ on 233 of them, Incheon on 191.

Right now

Incheon#132on the 24-hour board of 2,706, at 77 US AQI (23.1 µg/m³)

Seonghwan#40on the 24-hour board of 2,706, at 110 US AQI (39.1 µg/m³)

The last year, day by day

Incheon

Seonghwan

Each city's daily mean from 10 Oct 2025 to 9 Oct 2026, one stripe a day, coloured by band. A blank stripe is a day without a daily mean.

Month by month

Monthly means in µg/m³ over the days both cities were measured. Solid: Incheon. Faded: Seonghwan. A month shows once both share 10 such days. Dashed line: the WHO daily guideline, 15 µg/m³.

Year by year

Year	Incheon	Seonghwan	Days both measured	Days Incheon was worse
2026 so far	69	77	274	49
2025	70	76	351	86
2024	67	71	279	107

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

Incheon

14 Feb 202616169.3 µg/m³
17 Mar 202615662.7 µg/m³
13 Feb 202615560.7 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

Incheon

Side by side with Bucheon-si (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, Incheon and Seonghwan, 10 Oct 2025 – 9 Oct 2026, smogrank.com/compare/kr-incheon/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).