Porto vs Viseu
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.
Viseu has more tree cover — 48.2% against 20.8%.
Viseu has cleaner air right now — AQI 53 against 56.
- Tree cover gap
- 27.4 points
- Viseu is ahead.
- Air quality gap
- 3 AQI
- Viseu is cleaner.
- Trees between them
- 89.2K
- Viseu has more standing.
Tree cover
Share of the 2 km radius under canopy.
20.8%
48.2%
Air quality index
US EPA index, live, with its band. Lower is better.
56 · Moderate
53 · Moderate
Trees standing
Estimated from the measured canopy area.
62.2K
151K
Trees still needed
To reach the same canopy target. Fewer is better.
27.5K
0
CO₂ absorbed each year
By the trees already standing.
1.4M kg
3.3M 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. Porto is read from nearby ground stations and Viseu is modelled — worth knowing, since the two are not quite like for like.
PM2.5
Fine particles, the pollutant that usually sets the index.
14.7 µg/m³
12.9 µg/m³
PM10
Coarser particles — dust, pollen, road grit.
31.4 µg/m³
18.8 µg/m³
Nitrogen dioxide
Mostly traffic and combustion.
35 µg/m³
6.6 µg/m³
Ozone
Forms in sunlight; peaks on hot, still afternoons.
31 µg/m³
31 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 | Porto | Viseu |
|---|---|---|
| 22 Sept | 47 | 33 |
| 23 Sept | 57 | 38 |
| 24 Sept | 56 | 52 |
| 25 Sept | 57 | 46 |
| 26 Sept | 64 | 48 |
| 27 Sept | 43 | 52 |
| 28 Sept | 45 | 52 |
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. Viseu leads here at 48.2%.
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: Porto reads 56 (moderate) and Viseu reads 53 (moderate) right now.
Frequently asked
Porto and Viseu, answered
Which has more trees, Porto or Viseu?
Viseu, with roughly 151,425 trees inside its 2 km radius against 62,209. Tree cover tells a slightly different story from raw count: Viseu has the denser canopy at 48.2%.
Which has better air quality, Porto or Viseu?
Viseu right now, at AQI 53 against 56 — a gap of 3 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?
Porto needs about 27,515 more to reach its canopy target, and Viseu 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.
Keep going
Other comparisons nearby
Build your own
Compare Porto with somewhere else
This place
Porto
Want a different pair? Browse comparisons or measure any address.