Ansan-si vs Seongnam-si
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.
Ansan-si has more tree cover — 41.8% against 37.8%.
Ansan-si has cleaner air right now — AQI 36 against 56.
- Tree cover gap
- 4.0 points
- Ansan-si is ahead.
- Air quality gap
- 20 AQI
- Ansan-si is cleaner.
- Trees between them
- 12.2K
- Ansan-si has more standing.
South Korea
South Korea
Tree cover
Share of the 2 km radius under canopy.
41.8%
37.8%
Air quality index
US EPA index, live, with its band. Lower is better.
36 · Good
56 · Moderate
Trees standing
Estimated from the measured canopy area.
131K
119K
Trees still needed
To reach the same canopy target. Fewer is better.
0
0
CO₂ absorbed each year
By the trees already standing.
2.9M kg
2.6M 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. Seongnam-si is read from nearby ground stations and Ansan-si is modelled — worth knowing, since the two are not quite like for like.
PM2.5
Fine particles, the pollutant that usually sets the index.
8.6 µg/m³
14.6 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 | Ansan-si | Seongnam-si |
|---|---|---|
| 22 Sept | 60 | 72 |
| 23 Sept | 67 | 79 |
| 24 Sept | 69 | 92 |
| 25 Sept | 93 | 89 |
| 26 Sept | 54 | 66 |
| 27 Sept | 87 | 113 |
| 28 Sept | 59 | 67 |
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. Ansan-si leads here at 41.8%.
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: Ansan-si reads 36 (good) and Seongnam-si reads 56 (moderate) right now.
Frequently asked
Ansan-si and Seongnam-si, answered
Which has more trees, Ansan-si or Seongnam-si?
Ansan-si, with roughly 130,925 trees inside its 2 km radius against 118,752. Tree cover tells a slightly different story from raw count: Ansan-si has the denser canopy at 41.8%.
Which has better air quality, Ansan-si or Seongnam-si?
Ansan-si right now, at AQI 36 against 56 — a gap of 20 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?
Ansan-si needs about 0 more to reach its canopy target, and Seongnam-si about 0. 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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