Official guidance checked: .
A river walk is on your itinerary, but one app says “Moderate” while another shows an orange warning. Before cancelling the day—or ignoring both—check whether they describe the same pollutant, place, time and scale.
Start with AirKorea's official monitoring and forecast pages. Check PM2.5, PM10, the measurement time and the forecast for your destination, then read any active advisory. Use the forecast to arrange the day and recent local readings to check the plan again before leaving.
This guide is for travelers and residents deciding about ordinary outdoor activities in Korea. It is not today's air-quality report or a medical clearance for exercise. Follow local instructions and any personal advice from your clinician.
Before deciding from a colored number, ask:
Where was it measured? Which pollutant does it describe? How recent is it? Is it a concentration, an index or a forecast?
“Seoul: 40” is not enough information to answer those questions.
Jump to: Official sources · Korean dust levels · Forecasts · Conflicting apps · Outdoor plans · Troubleshooting
Where to check air quality in Korea in English
Open AirKorea's English Current Air Quality page. It provides region and station views, pollutant information and links to regional services. You can start with the website rather than making app registration your first task.
- Select the area you will actually visit. Check the station or district name, not only the city heading.
- Read PM2.5 and PM10 separately. Keep the pollutant label and unit visible when comparing another source.
- Check the measurement date and hour. A page that opens successfully may still show an earlier selection.
- Look at recent readings as well as the latest one. Then check the forecast and any issued warning before making a longer outdoor commitment.
AirKorea's English homepage explains that current readings are supplied at the end of each hour and are provisional before final approval. “Real time” should not be read as a second-by-second measurement at your hotel door.
For Seoul, the city's Air Quality Information portal adds local readings, 24-hour trends and notices. Check the selected layer: its supplementary sensor network is not the same dataset as the statutory monitoring network. A colored map is only useful when you know what it represents.
PM2.5 and PM10: Korean fine-dust levels explained
On Korean services, 미세먼지 commonly labels PM10, while 초미세먼지 labels PM2.5. The numbers refer to particle-size categories: generally 10 micrometers and smaller, or 2.5 micrometers and smaller. The U.S. EPA's particle-pollution explanation describes that distinction.
The readings below are concentrations in µg/m³—micrograms per cubic meter—not AQI scores. These are the published Korean concentration bands:
- 좋음 — Good
- PM2.5: 0–15 µg/m³ · PM10: 0–30 µg/m³
- 보통 — Moderate
- PM2.5: 16–35 µg/m³ · PM10: 31–80 µg/m³
- 나쁨 — Unhealthy
- PM2.5: 36–75 µg/m³ · PM10: 81–150 µg/m³
- 매우나쁨 — Very unhealthy
- PM2.5: 76 µg/m³ and above · PM10: 151 µg/m³ and above
Source: AirKorea's concentration and index explanation. Check the displayed averaging period; these bands are not a personal safe-exposure timetable.
Do not use the skyline as a substitute for a reading. Some particles are too small to see, as the EPA explanation notes. A view that photographs well is not an air-quality measurement.
Use the fine-dust forecast for planning, not as a reading for every hour
AirKorea's today, tomorrow and day-after-tomorrow forecast is issued four times daily: 05:00, 11:00, 17:00 and 23:00 Korea Standard Time. Check both the issue time and the day being forecast.
오늘 means today, 내일 tomorrow, and 모레 the day after tomorrow. Match the forecast region to your destination rather than the place where you opened the page.
The fine-dust forecast grade is based on the daily average and uses the worse grade of PM10 and PM2.5. Read the written explanation too: it may identify temporary deterioration or a particular part of the day. A moderate daily forecast does not promise moderate conditions throughout every outdoor stop.
For 황사—yellow dust—AirKorea also points to KMA's yellow-dust model information. A model prediction and a local measured concentration are different products.
Why two air-quality apps can disagree
Before downloading a third app, compare the labels on the first two. One might show PM2.5 concentration at a station; another might show an overall index for a wider area. A city average, an hourly reading and a moving average do not answer exactly the same question.
Korean CAI is not the same as U.S. AQI
Korea's 통합대기환경지수, or CAI, combines information about several pollutants into an index with four broad categories. Its particulate calculation uses a 24-hour predicted moving average based on recent measurements; that is not tomorrow's calendar-day forecast. See AirKorea's CAI methodology.
The U.S. EPA's AQI explanation describes a different system with six categories. An app using U.S. AQI can assign a different color or label from a Korean service. Read its scale setting instead of treating one color scheme as universal.
Illustrative comparison: “PM2.5: 40 µg/m³” and “AQI: 40” are not equivalent. The first is a pollutant concentration; the second is an index value. The number alone does not make them comparable.
Match the pollutant, station or area, timestamp, unit and averaging method. If those still do not explain a large difference, check the app's stated data provider and contact support with both readings. Do not average unrelated scores or choose whichever app makes your original plan look easier.
Should you change a walk, hike or outdoor workout?
Use the grade together with the activity and the people taking part. A brief necessary walk and a strenuous afternoon hike are different exposure decisions.
AirKorea's behavioral guidance distinguishes the general public from sensitive groups and recommends increasingly limiting prolonged or strenuous outdoor activity as pollution worsens.
- Good or moderate
- Check any pollutant-specific advice and your own sensitivity. Do not read “moderate” as a promise that everybody can ignore symptoms.
- Unhealthy
- Reduce prolonged or strenuous outdoor activity. Sensitive people should be more cautious and follow the relevant health guidance rather than the group's preferred schedule.
- Very unhealthy
- Move optional outdoor exercise indoors or postpone it. Sensitive people should avoid outdoor activity in line with the official guidance; everyone should avoid prolonged or heavy exertion outside.
People with heart or lung disease, children and older adults are among those at greater risk from particle pollution, according to the EPA's health-effects summary. If you have asthma or another relevant condition, use a plan agreed with your clinician. Do not change medication doses because of a blog's color chart.
Change the part of the day that creates the most exposure
A practical adjustment is to postpone the hill walk, outdoor run or long cycling route first. Keep an indoor booking if it remains appropriate, and reduce unnecessary walking between stops. Seoul's fine-dust advice also recommends avoiding heavy exertion and limiting time near busy roads and construction.
For example, suppose your plan contains a hike today and a museum tomorrow. If current guidance calls for limiting outdoor activity, swap the indoor visit forward after checking its opening hours. Leave the hike conditional on a fresh check; moving it to tomorrow does not guarantee cleaner air.
Our 10-day Korea itinerary groups activities geographically. Use that structure to rearrange a city's indoor and outdoor stops before making unnecessary changes to intercity travel.
For your own route, the Korea Trip Planner can help organize changes. It is a planning tool, not a replacement for a live air-quality check. Verify the alternative venue, journey and admission arrangements separately.
Low fine dust does not settle the ozone question
Also check 오존, or O3. Ground-level ozone is a gas, not another name for fine dust. It forms through reactions involving other pollutants and sunlight; unhealthy levels can occur on sunny days. The EPA's ozone explanation describes the difference.
Seoul's high-ozone guidance recommends adjusting outdoor activity and moving indoors when concentrations are high. Do not treat a low PM2.5 reading, a blue sky or wearing a particulate mask as permission to ignore an ozone warning.
There is no single “always safe” hour for every pollutant and location. Recheck the relevant forecast and readings when rescheduling exercise, and consider heat and weather conditions as separate checks.
Will a mask or an indoor plan solve the problem?
For high particle pollution, Seoul recommends an MFDS-approved health mask and checking the fit around the face. Its mask guidance also flags breathing difficulty and the need for appropriate medical advice for vulnerable users. A mask is not a reason to keep the same strenuous itinerary regardless of conditions.
Ask a pharmacist for an appropriate fine-dust mask and size if you are unsure. Do not push through breathing discomfort to finish an activity.
Indoors, look for a space with appropriate air management, not merely a roof. The EPA's home-filtration guide explains that filtration supplements source control and ventilation with clean outdoor air; an air cleaner does not remove every pollutant.
At home, avoid adding smoke and other avoidable indoor pollution. Seoul's advice balances outdoor conditions with necessary ventilation and cooking exhaust. “Keep every window closed indefinitely” is not a complete indoor-air plan. Follow your building and equipment instructions, and reassess ventilation as outdoor conditions change.
Forecasts, advisories and phone alerts are separate things
예보 means forecast; 주의보 is an advisory; 경보 is a warning; and 해제 means a notice has been lifted. Check which pollutant and area each notice covers.
AirKorea's fine-dust advisory and warning page lists issuance and lifting information. Formal advisories use their own criteria, including how long concentrations remain elevated. They are not simply another name for a daily forecast grade.
Seoul offers an air-quality notification service. Its published rules include no messages during 21:00–06:00, and it warns that messages may fail to arrive. Check current signup conditions and do not assume English messages or support for your phone setup.
No notification is not an all-clear. Check the official pages directly before a significant outdoor activity, even if your phone has been quiet.
When the air-quality check does not work
The map is blank, or your location is wrong
Select the region manually and check the station name. If you recently traveled, remove an old favorite from the decision rather than assuming the app has followed you.
If the map still fails, try AirKorea's regional PM2.5 data view or a linked regional service. Check the selected date and time. A dash, missing station or unavailable reading is not zero pollution.
Use another reporting station as context while noting the different location. Do not quietly substitute a distant city's reading for the place where you intend to exercise.
The page shows yesterday's reading
Check your connection, refresh the page and inspect its selected date. Compare with a second official page. Keep the timestamp in any screenshot you send to a companion; a saved image remains useful as a record, not as a live forecast.
If data is missing while an advisory is active, follow the advisory and current local instructions rather than assuming the missing update means conditions improved.
The forecast is in Korean and translation looks confusing
Translate the explanatory sentence with the region, issue time and forecast date still visible. Check numbers and words such as 일시적으로 (temporarily), 오전 (morning) and 오후 (afternoon) against the original.
Our Korea travel apps guide covers mapping and translation preparation. Ask hotel staff, your host or the activity operator to clarify a notice you cannot interpret. Keep health or closure instructions distinct from a translated app's summary.
You have already paid for an outdoor tour
Contact the operator through the original booking channel. Give the date, destination and relevant official notice. Ask whether the route can change, an indoor alternative is available, or rescheduling is possible—and what charges or cancellation deadline apply.
Keep the answer in writing. A pollution forecast does not tell you what your particular booking contract allows, and an operator continuing a tour does not establish that it suits your health needs.
대기질이 좋지 않아 야외 활동을 줄이려고 합니다. 실내 일정으로 변경하거나 날짜를 바꿀 수 있나요? 추가 비용과 취소 조건도 알려 주세요.
The air quality is poor, so I would like to reduce outdoor activity. Can we change to an indoor itinerary or another date? Please also explain any additional charge and cancellation conditions.
You develop symptoms even though the app looks reassuring
Stop the activity and move away from the exposure to a suitable place. Particle pollution can affect the heart and lungs and aggravate coughing or breathing problems, as the EPA's health guidance explains. A favorable area reading should not override symptoms or your medical plan.
Seek medical advice for persistent or worsening symptoms rather than diagnosing the cause from an app. For an urgent medical emergency, call 119 and ask for an ambulance; this is the number listed in the UK government's official South Korea health guidance. Do not spend an emergency comparing monitors.
A quick check before you head outside
Confirm the destination, recent PM2.5 and PM10 readings, the latest forecast and any active warning. Check ozone separately. Then decide whether the planned duration and effort still make sense for everyone going.
Keep one practical alternative nearby and a time to check again. The aim is not to find an app that approves your original itinerary. It is to understand the information well enough to change the part of the day that needs changing.
Sources and scope: AirKorea supports the monitoring, Korean concentration bands, CAI, forecasts and advisory information. Seoul's official portal supports its local notification service and public guidance. EPA sources explain particles, ozone, the U.S. AQI system, health risks and household filtration; they do not define Korean alert criteria. The UK government source confirms Korea's emergency ambulance number.
Official pages and linked AllThingsK8282 resources were checked on September 28, 2026. The app-comparison workflow, itinerary example and Korean booking message are editorial guidance, not a personally tested pollution episode, a refund promise or an individual exposure limit. Live readings, service interfaces and notices can change; check them for your actual location and activity.
0 Comments