Jeju has 14 air quality monitoring stations, 14 of which also measure PM2.5. You can read the current levels starting from the station nearest to you.
Jeju is the cleanest region in Korea. Sea on every side means the wind never stops, and there are no large industrial complexes. That is why Jeju readings serve as the baseline for Korean air.
Jeju is an island. Whichever direction the wind comes from, the air has crossed the sea and been rinsed on the way. There is no inland pocket for pollutants to pile up in.
It emits little of its own, too. There are no large power, chemical or steel facilities; tourism and farming matter more here than industry. So Jeju numbers generally stay low.
At Gosan, on the western tip, there is a national background station. Because it measures where domestic emissions barely reach, a rise there reads as a signal that "the share coming from outside the country has gone up". In effect it is a reference point for judging air quality nationwide.
Jeju is clean because it emits little itself, not because it blocks what arrives from elsewhere. When there is Asian dust or a large inflow from outside, Jeju takes it just the same.
Depending on the path, there are even days when it arrives before the mainland. When a normally "good" Jeju suddenly turns "unhealthy", it is almost always something that came in.
Hallasan rises in the middle of the island, so the weather differs north and south. The wind splits as it crosses the mountain, and on some days Jeju City and Seogwipo read differently because of it.
Spring is the season to watch. It is when Asian dust and inflow from outside concentrate. The days Jeju shows "unhealthy" are usually in spring.
In summer and autumn the wind turns southerly and rain is frequent, and the air is very clean. This is the best stretch of the year.
In winter there is a share riding in on the northwesterly, but without the heating and stagnation that mainland cities pile on top, it is far better here.
Readings vary quite a bit between stations even within the same region — roadside or residential, close to an industrial area or not. Below are the stations in Jeju grouped by district.
Station and district names are shown in Korean, exactly as the monitoring agency publishes them.
| District | Count | Stations |
|---|---|---|
| 제주시 | 9 | 고산리, 노형로, 애월읍, 연동, 이도동, 제주항, 조천읍, 한림읍, 화북동 |
| 서귀포시 | 5 | 강정동, 남원읍, 대정읍, 동홍동, 성산읍 |
Stations are grouped into networks according to what they were built to watch.
What each level means and what to do about it is in the air quality scale. If you need to pick a mask, see choosing a mask; if indoor air is on your mind, see indoor air.
Some days a station goes quiet because of maintenance or a network fault. When that happens, just swipe to the next one — Jeju has 14, so there is almost always another nearby.
It does — mainly in spring, with Asian dust or inflow from outside the country. Jeju is clean because it emits little itself, not because it keeps out what arrives.
Hallasan is in the middle. The wind splits as it crosses the mountain, so on some days the weather and the air read differently north and south.
It is a national background station. Because it measures where domestic emissions barely reach, it is used as the reference point for judging how much is coming in from outside.