Bilbao vs Madrid
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.
Bilbao has more tree cover — 43.9% against 20.1%.
Madrid has cleaner air right now — AQI 57 against 76.
- Tree cover gap
- 23.8 points
- Bilbao is ahead.
- Air quality gap
- 19 AQI
- Madrid is cleaner.
- Trees between them
- 74.6K
- Bilbao has more standing.
Tree cover
Share of the 2 km radius under canopy.
43.9%
20.1%
Air quality index
US EPA index, live, with its band. Lower is better.
76 · Moderate
57 · Moderate
Trees standing
Estimated from the measured canopy area.
138K
63.0K
Trees still needed
To reach the same canopy target. Fewer is better.
0
31.0K
CO₂ absorbed each year
By the trees already standing.
3.0M kg
1.4M 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.
24 µg/m³
15 µg/m³
Nitrogen dioxide
Mostly traffic and combustion.
26 µg/m³
58 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 | Bilbao | Madrid |
|---|---|---|
| 22 Sept | 35 | 30 |
| 23 Sept | 36 | 32 |
| 24 Sept | 42 | 38 |
| 25 Sept | 50 | 35 |
| 26 Sept | 38 | 33 |
| 27 Sept | 44 | 31 |
| 28 Sept | 47 | 33 |
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. Bilbao leads here at 43.9%.
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: Bilbao reads 76 (moderate) and Madrid reads 57 (moderate) right now.
Frequently asked
Bilbao and Madrid, answered
Which has more trees, Bilbao or Madrid?
Bilbao, with roughly 137,640 trees inside its 2 km radius against 63,020. Tree cover tells a slightly different story from raw count: Bilbao has the denser canopy at 43.9%.
Which has better air quality, Bilbao or Madrid?
Madrid right now, at AQI 57 against 76 — a gap of 19 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?
Bilbao needs about 0 more to reach its canopy target, and Madrid about 31,040. 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
Other comparisons nearby
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- Bilbao vs Donostia / San Sebastián47% tree cover · AQI 60Compare
- Bilbao vs Logroño25% tree cover · AQI 28Compare
- Bilbao vs Alcobendas13% tree cover · AQI 19Compare
- Bilbao vs Móstoles13% tree cover · AQI 33Compare
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