Changwon vs Ulsan
Tree cover and air quality for both, measured the same way: Sentinel-2 imagery at 10 m detail over a 2 km radius from each city centre, and the live US EPA air quality index. Same radius and same index, so the two numbers compare directly.
Changwon has more tree cover — 37.1% against 26.2%.
Ulsan has cleaner air right now — AQI 33 against 49.
- Tree cover gap
- 10.9 points
- Changwon is ahead.
- Air quality gap
- 16 AQI
- Ulsan is cleaner.
- Trees between them
- 37.8K
- Changwon has more standing.
Tree cover
Share of the 2 km radius under canopy.
37.1%
26.2%
Air quality index
US EPA index, live, with its band. Lower is better.
49 · Good
33 · Good
Trees standing
Estimated from the measured canopy area.
116K
78.4K
Trees still needed
To reach the same canopy target. Fewer is better.
0
11.4K
CO₂ absorbed each year
By the trees already standing.
2.6M kg
1.7M kg
Air quality in detail
What each city is breathing
Concentrations in µg/m³, measured at the same moment as the index above. Lower is better in every row. Ulsan is read from nearby ground stations and Changwon is modelled — worth knowing, since the two are not quite like for like.
PM2.5
Fine particles, the pollutant that usually sets the index.
11.7 µg/m³
8 µg/m³
The last week, day by day
A single reading can catch a city on a bad afternoon. The week says whether it was the weather or the place.
| Day | Changwon | Ulsan |
|---|---|---|
| 22 Sept | 40 | 38 |
| 23 Sept | 47 | 42 |
| 24 Sept | 60 | 68 |
| 25 Sept | 73 | 74 |
| 26 Sept | 53 | 41 |
| 27 Sept | 56 | 56 |
| 28 Sept | 61 | 60 |
Reading these numbers
What is actually being measured
Tree cover
The share of ground under canopy inside a 2 km radius of each city centre, read from Sentinel-2 satellite imagery at 10 m detail. It is a measurement of that circle, not of the whole municipality — which is exactly what makes the two comparable, since city boundaries are drawn to wildly different rules around the world. Changwon leads here at 37.1%.
Air quality index
The live US EPA index, computed from current pollutant concentrations — ground stations where a city has them nearby, and a model everywhere else. It moves hour to hour, so this is a snapshot rather than a verdict on either place: Changwon reads 49 (good) and Ulsan reads 33 (good) right now.
Frequently asked
Changwon and Ulsan, answered
Which has more trees, Changwon or Ulsan?
Changwon, with roughly 116,203 trees inside its 2 km radius against 78,359. Tree cover tells a slightly different story from raw count: Changwon has the denser canopy at 37.1%.
Which has better air quality, Changwon or Ulsan?
Ulsan right now, at AQI 33 against 49 — a gap of 16 points. This is a live reading rather than an annual average, so it can reverse within a day.
How many more trees does each city need?
Changwon needs about 0 more to reach its canopy target, and Ulsan about 11,365. The target is the same share of ground for both, so the figures are directly comparable.
Are these two measured the same way?
Yes — that is the point of the page. Identical radius, identical satellite source at 10 m detail, and the same US EPA index for air. Nothing here is adjusted for population, city limits or climate, so the numbers describe the same-sized circle of ground in each place.
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