Fine Dust and Air Quality in Korea: A Visitor's Guide

What fine dust and yellow dust are

Koreans talk about the air almost as often as the weather. Three words cover most of it:

• 미세먼지 (misemeonji), “fine dust”: officially PM10, airborne particles 10 micrometres across or smaller. In everyday speech the word covers all air pollution haze.
• 초미세먼지 (chomisemeonji), “ultrafine dust”: PM2.5, particles 2.5 micrometres or smaller. It’s the number the government tracks most closely.
• 황사 (hwangsa), “yellow dust”: natural dust blown in from the deserts and dry lands of northern China and nearby regions. It’s coarser than PM2.5 and can turn the sky a hazy yellow-brown.

Fine dust comes from a mix of local sources (traffic, industry, heating) and pollution carried on the wind from abroad. On a bad day you’ll see a grey haze over the city and many people in masks.

Which months are worst

December to March is the fine dust season. Korea’s government runs a Fine Dust Seasonal Management Program (미세먼지 계절관리제, misemeonji gyejeol gwanlije) every year from 1 December to 31 March, because that’s when high concentrations happen most often. In the 2024–25 season the national PM2.5 average was 20.3 µg/m³, the lowest since the program started in 2019, with 54 “good” days and 12 “bad” days (Ministry of Environment, April 2025). For the 2025–26 season the target was 19 µg/m³.

Yellow dust is mainly a spring problem. In the Korea Meteorological Administration’s (KMA) figures for spring, April has the most yellow dust days on average, followed by March and then May. KMA notes it can also occur in autumn and winter, but summer is largely free of it.

Months	What to expect
Dec–Mar	Highest fine dust risk; seasonal controls in force
Mar–May	Yellow dust most likely, especially April
Summer	Yellow dust is rare (KMA)
Any month	Hazy days are possible; check the daily forecast

These are averages. Any single week can be clear or hazy depending on the wind. For weather and crowds month by month, see the best time to visit Korea.

Reading Korea’s air quality grades

Korea uses four grades, based on the 24-hour average concentration (µg/m³). These are the official AirKorea cut-offs:

Grade	Korean	PM10	PM2.5
Good	좋음 (joeum)	0–30	0–15
Moderate	보통 (botong)	31–80	16–35
Bad / Unhealthy	나쁨 (nappeum)	81–150	36–75
Very bad / Very unhealthy	매우나쁨 (maeu nappeum)	151+	76+

A few things to know:

• The forecast uses the worse of the two. If PM10 is “moderate” but PM2.5 is “bad”, the day is forecast as “bad”.
• Colours: AirKorea shows good in blue, moderate in green, bad in yellow and very bad in red. Korean apps often use similar colours, sometimes with smiley or frowny faces.
• AirKorea’s English site calls the bad grade “Unhealthy”, while Korean apps say 나쁨, which translates as “bad”. They’re the same thing.
• Advisories (주의보, juuibo) are issued when the hourly average stays high for two hours: PM2.5 at 75 or more, or PM10 at 150 or more. A warning (경보, gyeongbo) is issued at PM2.5 150+ or PM10 300+.

Where to check in English

• AirKorea website (airkorea.or.kr/eng): the official national monitoring network, run by the Korea Environment Corporation. The English site has current readings by station, the grade scale and trends. This is the source to trust.
• AirKorea app (에어코리아 - 우리동네대기정보): free on iOS and Android, with real-time PM2.5, PM10 and ozone and a three-day forecast. The Korea Environment Corporation announced an English mode in December 2025, but as of October 2026 the App Store listing still shows Korean only. Install it and check the language settings.
• Naver and Daum/Kakao weather: the big Korean portals show air quality next to the weather, but we couldn’t confirm an English version of their weather pages. If you already use Naver Map or KakaoMap, the Korean grade words in the table above are enough to read them.
• International apps (your phone’s weather app, IQAir and others) are fine for a rough idea, but they usually use a different index. Don’t mix their numbers with Korean grades.

What to do on a bad day

Wear a KF mask outdoors. “KF” stands for Korea Filter, a rating certified by the Ministry of Food and Drug Safety (MFDS):

Mark	What it means (MFDS)	Notes
KF80	Filters at least 80% of particles averaging 0.6 µm	Easiest to breathe through
KF94	Filters at least 94% of particles averaging 0.4 µm	The most common choice for dust days
KF99	Filters at least 99% of particles averaging 0.4 µm	Hardest to breathe through

• Buying: KF masks are sold at convenience stores, pharmacies (약국, yakguk) and drugstore chains. Check the pack for the KF mark and 의약외품 (uiyagoepum, “quasi-drug”), the label for MFDS-regulated products.
• Fit matters: cover your nose and mouth fully, pinch the nose wire, and don’t touch the front. MFDS ranks breathability in reverse order, so a higher number isn’t always more comfortable for a long day of walking.
• Pack a few from home if you need a specific size. Our What to Pack list has a spring reminder.

Swap outdoor plans for indoor ones. On a “very bad” day, consider moving hikes, palace walks and riverside cycling to another day, and fill the gap with:

• Museums, such as the National Museum of Korea
• Big shopping and entertainment complexes, which connect to subway stations
• Underground shopping arcades around major stations
• Cafés, galleries, spas and saunas (jjimjilbang)

Plan My Days makes it easy to swap two days around if the forecast looks bad.

Emergency reduction measures

When PM2.5 is forecast to stay high, city and provincial governments can issue emergency reduction measures (비상저감조치, bisang jeogam jochi). These mainly affect drivers and businesses:

• Older diesel cars (emission grade 5) are restricted. In Seoul this runs 06:00–21:00 on weekdays during the seasonal program, with a ₩100,000 fine.
• Some public car parks close, and construction sites and power plants cut back.
• Road cleaning is stepped up.

For most visitors nothing changes: public transport runs normally. If you rent a car, ask the rental company whether the restrictions could apply to it.

People who should be more careful

AirKorea’s grade descriptions single out people with conditions linked to air pollution and “sensitive groups”, such as children, older adults and people in poor health, as the ones most affected on “bad” and “very bad” days. If that’s you or someone you’re travelling with:

• Check the forecast the evening before, and plan shorter outdoor stretches on bad days.
• Bring any medicines you normally use, in your carry-on.
• If you have questions about your own health, ask your doctor before you travel. For help during your trip, see emergency help in Korea.