Hong Kong vs Nantou
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.
Hong Kong has more tree cover — 50.6% against 12.3%.
Nantou has cleaner air right now — AQI 90 against 94.
- Tree cover gap
- 38.3 points
- Hong Kong is ahead.
- Air quality gap
- 4 AQI
- Nantou is cleaner.
- Trees between them
- 70.3K
- Hong Kong has more standing.
Tree cover
Share of the 2 km radius under canopy.
50.6%
12.3%
Air quality index
US EPA index, live, with its band. Lower is better.
94 · Moderate
90 · Moderate
Trees standing
Estimated from the measured canopy area.
108K
37.9K
Trees still needed
To reach the same canopy target. Fewer is better.
0
54.5K
CO₂ absorbed each year
By the trees already standing.
2.4M kg
834K 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. Hong Kong is read from nearby ground stations and Nantou is modelled — worth knowing, since the two are not quite like for like.
PM2.5
Fine particles, the pollutant that usually sets the index.
32.7 µg/m³
13.8 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 | Hong Kong | Nantou |
|---|---|---|
| 22 Sept | 127 | 182 |
| 23 Sept | 105 | 161 |
| 24 Sept | 94 | 147 |
| 25 Sept | 99 | 124 |
| 26 Sept | 102 | 117 |
| 27 Sept | 69 | 80 |
| 28 Sept | 54 | 58 |
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. Hong Kong leads here at 50.6%.
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 94 (moderate) and Nantou reads 90 (moderate) right now.
Frequently asked
Hong Kong and Nantou, answered
Which has more trees, Hong Kong or Nantou?
Hong Kong, with roughly 108,255 trees inside its 2 km radius against 37,907. Tree cover tells a slightly different story from raw count: Hong Kong has the denser canopy at 50.6%.
Which has better air quality, Hong Kong or Nantou?
Nantou right now, at AQI 90 against 94 — a gap of 4 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?
Hong Kong needs about 0 more to reach its canopy target, and Nantou about 54,550. 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.
Keep going
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- Hong Kong vs Shenzhen38% tree cover · AQI 65Compare
- Hong Kong vs Daliang22% tree cover · AQI 97Compare
- Hong Kong vs Zhongshan26% tree cover · AQI 51Compare
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