Sejong air quality now

South Korea · The summary is refreshed every 15 minutes.

November 12

The air is moderate now

Measured 06:00

Sejong

4°C

Cloudy

81AQI

1027

hPa

Atmospheric
pressure

100%

Humidity

Sejong, November 10, 2026: daily mean PM2.5 15 µg/m³ (4 sensors), level “Moderate” — as in the Atmy Data Hub. Now (07:00 local time): 25.3 µg/m³. Open methodology and data in JSON: Methodology and data sources · JSON

Right now in Sejong, PM2.5 averages 25.3 µg/m³ — “moderate” on the US EPA scale (approximate, from hourly readings). Mean of 4 sensors from Government stations, readings from 06:00–06:00 local time (21:00–21:00 UTC), summary prepared at 07:00 local time. Median: 25.0 µg/m³; range across sensors: 24.0–27.0 µg/m³.

In Sejong the air is moderate 🟡 AQI 81. About the same as three hours ago. ☁️ +4 °C · No precipitation · Wind 3 m/s

In Sejong the air is moderate right now (approximate, US EPA scale). From 18:00 to 07:00 local time the city mean PM2.5 stayed roughly level: from 27.8 to 25.3 µg/m³.

Cold weather (4°C) possibly means more heating, a common source of particles. High humidity (100%) possibly makes optical sensors read somewhat higher.

Weather now: cloudy, 4°C, wind 3 m/s, humidity 100%. No major change in the wind is expected in the coming hours. By 18:00 the temperature will be about 12°C.

Written automatically at 07:00 local time (22:00 UTC) from sensor measurements and the weather forecast. Values are approximate; hypotheses are marked.

3 m/s

Wind, SSE

0 mm

Precipitation today

Sejong: air quality for the completed day

Metric: PM2.5, µg/m³ · Color scale: EPA AQI · November 10, 2026 · 00:00–24:00 UTC = 09:00–09:00 UTC+9

15 µg/m³ Moderate

Daily mean PM2.5 on November 10, 2026 (00:00–24:00 UTC = 09:00–09:00 UTC+9): 15 µg/m³ from 4 sensors that passed the quality check — the same value as in the Atmy Data Hub.

No. 13 of 39 cities in South Korea and No. 412 of 676 worldwide, from the most polluted.

LowModerateElevatedHighVery highExtremely high

Pollution accumulation index now

38/100Moderate · An estimate of weather conditions · not a PM2.5 forecast

Now3841
07.0015.0022.0006.00

Pollution accumulation forecast

Today — November 12

16°/4°

Index by time of day

55/100Moderate

  1. 55/100Night
  2. 39/100Morning
  3. 10/100Day
  4. 22/100Evening

Friday — November 13

18°/7°

Index by time of day

55/100Moderate

  1. 55/100Night
  2. 41/100Morning
  3. 10/100Day
  4. 21/100Evening

Saturday — November 14

15°/12°

Index by time of day

52/100Moderate

  1. 52/100Night
  2. 36/100Morning
  3. 7/100Day
  4. 18/100Evening

Sunday — November 15

19°/8°

Index by time of day

44/100Moderate

  1. 44/100Night
  2. 37/100Morning
  3. 8/100Day
  4. 27/100Evening

Monday — November 16

17°/6°

Index by time of day

55/100Moderate

  1. 55/100Night
  2. 38/100Morning
  3. 6/100Day
  4. 16/100Evening

Tuesday — November 17

15°/8°

Index by time of day

49/100Moderate

  1. 49/100Night
  2. 34/100Morning
  3. 7/100Day
  4. 20/100Evening

Forecast of conditions that trap pollution near the surface

Weather

4°

Cloudy. Feels like 1°C

  1. MorningCloudy5°C99%
  2. DayClear16°C66%
  3. EveningPartly cloudy9°C93%

Wind

3m/sWind from the SSE

0m/sWind gusts

Wind force: 2

Gusts up to 4 m/s are expected.

10-day weather forecast for Sejong

South Korea

  1. TodayNov 12Cloudy16°C4°C
  2. FriNov 13Cloudy18°C7°C
  3. SatNov 14Rain15°C12°C
  4. SunNov 15Cloudy19°C8°C
  5. MonNov 16Cloudy17°C6°C
  6. TueNov 17Rain15°C8°C
  7. WedNov 18Rain11°C5°C
  8. ThuNov 19Cloudy5°C1°C
  9. FriNov 20Cloudy10°C0°C
  10. SatNov 21Cloudy14°C3°C

Where in Sejong is the air worse?

See all sensors

Highest current reading: 27.0 µg/m³ (아름동 (한국환경공단 에어코리아 (AirKorea))). Lowest: 24.0 µg/m³ (한솔동 (한국환경공단 에어코리아 (AirKorea))). The list shows every sensor, highest first.

  1. 아름동 (한국환경공단 에어코리아 (AirKorea)) →27 µg/m³
  2. 전의면 (한국환경공단 에어코리아 (AirKorea)) →26 µg/m³
  3. 보람동 (한국환경공단 에어코리아 (AirKorea)) →24 µg/m³
  4. 한솔동 (한국환경공단 에어코리아 (AirKorea)) →24 µg/m³

Source: atmy.ai monitoring network

Who provides the data

Sensors in the summary by network: Government stations — 4 sensors.

Atmy shows the networks’ readings after the Data Hub’s quality check: test devices and sensors that fail it are left out.

South Korea: sensors in total

529

  1. SeoulSouth Korea

    34

  2. BusanSouth Korea

    30

  3. IncheonSouth Korea

    27

Cities with the most sensors

All sensors on the map, by city as the map assigns them; the city’s values count only the sensors that pass the Data Hub’s quality check.

Air quality calendar: Sejong

Daily mean PM2.5 of the city sensors, µg/m³

Click a day to see its date and value.

LowModerateElevatedHighVery highExtremely high

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Air quality in Sejong now — Atmy

South Korea · City ranking · All pilot cities

Questions

What was the air quality in Sejong over the last completed day?

Daily mean PM2.5 on November 10, 2026 (00:00–24:00 UTC = 09:00–09:00 UTC+9): 15 µg/m³ from 4 sensors that passed the quality check — the same value as in the Atmy Data Hub. No. 13 of 39 cities in South Korea and No. 412 of 676 worldwide, from the most polluted.

What is the air quality in Sejong right now?

Right now in Sejong, PM2.5 averages 25.3 µg/m³ — “moderate” on the US EPA scale (approximate, from hourly readings). Mean of 4 sensors from Government stations, readings from 06:00–06:00 local time (21:00–21:00 UTC), summary prepared at 07:00 local time. Median: 25.0 µg/m³; range across sensors: 24.0–27.0 µg/m³.

Is it safe to be outdoors in Sejong now?

The current level is “moderate” (US EPA scale, approximate). Unusually sensitive people should consider reducing prolonged or heavy exertion outdoors. This is the standard guidance of the scale, not medical advice.

Where in Sejong is the air worse?

Highest current reading: 27.0 µg/m³ (아름동 (한국환경공단 에어코리아 (AirKorea))). Lowest: 24.0 µg/m³ (한솔동 (한국환경공단 에어코리아 (AirKorea))). The list shows every sensor, highest first.

Where do these data come from?

From Atmy sensors and connected public networks (citizen, experimental and government monitors), aggregated by Atmy. Values are approximate; see the methodology.

How often is this page updated?

The summary is rebuilt every 15 minutes from the latest reading of each sensor, each no older than one hour.

Data

Where do these data come from?

The daily value is the Data Hub’s: the mean of the city’s sensors that passed the nightly quality check, each with at least 12 valid hours, and only with sensors at four places 500 m apart; days are UTC.

“Now” uses the same sensors and rule: the mean of their latest readings, each at most 60 minutes old, shown only with sensors at four places 500 m apart reporting.

Source: public Atmy monitoring data. Methodology and data sources · Data terms