Hong Kong vs San Tung Chung Hang
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.
San Tung Chung Hang has more tree cover — 81.8% against 50.6%.
Both are reading the same air quality index.
- Tree cover gap
- 31.2 points
- San Tung Chung Hang is ahead.
- Air quality gap
- 0 AQI
- Both reading the same.
- Trees between them
- 120K
- San Tung Chung Hang has more standing.
Hong Kong
Hong Kong
Tree cover
Share of the 2 km radius under canopy.
50.6%
81.8%
Air quality index
US EPA index, live, with its band. Lower is better.
28 · Good
28 · Good
Trees standing
Estimated from the measured canopy area.
108K
229K
Trees still needed
To reach the same canopy target. Fewer is better.
0
0
CO₂ absorbed each year
By the trees already standing.
2.4M kg
5.0M 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. Both are read from nearby ground stations.
PM2.5
Fine particles, the pollutant that usually sets the index.
6.6 µg/m³
6.6 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 | Hong Kong | San Tung Chung Hang |
|---|---|---|
| 22 Sept | 127 | 127 |
| 23 Sept | 105 | 105 |
| 24 Sept | 94 | 94 |
| 25 Sept | 99 | 99 |
| 26 Sept | 102 | 102 |
| 27 Sept | 69 | 69 |
| 28 Sept | 50 | 50 |
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. San Tung Chung Hang leads here at 81.8%.
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: Hong Kong reads 28 (good) and San Tung Chung Hang reads 28 (good) right now.
Frequently asked
Hong Kong and San Tung Chung Hang, answered
Which has more trees, Hong Kong or San Tung Chung Hang?
San Tung Chung Hang, with roughly 228,714 trees inside its 2 km radius against 108,255. Tree cover tells a slightly different story from raw count: San Tung Chung Hang has the denser canopy at 81.8%.
Which has better air quality, Hong Kong or San Tung Chung Hang?
Both are reading 28 on the US EPA index at the moment. Air quality changes through the day, so this can separate within hours.
How many more trees does each city need?
Hong Kong needs about 0 more to reach its canopy target, and San Tung Chung Hang 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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