Port Louis vs Saint-Pierre
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.
Saint-Pierre has more tree cover — 33.7% against 28.6%.
Port Louis has cleaner air right now — AQI 16 against 20.
- Tree cover gap
- 5.1 points
- Saint-Pierre is ahead.
- Air quality gap
- 4 AQI
- Port Louis is cleaner.
- Trees between them
- 3.9K
- Port Louis has more standing.
Mauritius
Reunion
Tree cover
Share of the 2 km radius under canopy.
28.6%
33.7%
Air quality index
US EPA index, live, with its band. Lower is better.
16 · Good
20 · Good
Trees standing
Estimated from the measured canopy area.
82.3K
78.5K
Trees still needed
To reach the same canopy target. Fewer is better.
4.0K
0
CO₂ absorbed each year
By the trees already standing.
1.8M kg
1.7M 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 modelled, with no ground station close enough to either.
PM2.5
Fine particles, the pollutant that usually sets the index.
3.8 µg/m³
4.7 µg/m³
PM10
Coarser particles — dust, pollen, road grit.
5.5 µg/m³
7.6 µg/m³
Nitrogen dioxide
Mostly traffic and combustion.
3.4 µg/m³
2.6 µg/m³
Ozone
Forms in sunlight; peaks on hot, still afternoons.
30 µg/m³
37 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 | Port Louis | Saint-Pierre |
|---|---|---|
| 22 Sept | 29 | 26 |
| 23 Sept | 39 | 38 |
| 24 Sept | 41 | 47 |
| 25 Sept | 34 | 38 |
| 26 Sept | 26 | 29 |
| 27 Sept | 23 | 26 |
| 28 Sept | 20 | 20 |
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. Saint-Pierre leads here at 33.7%.
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: Port Louis reads 16 (good) and Saint-Pierre reads 20 (good) right now.
Frequently asked
Port Louis and Saint-Pierre, answered
Which has more trees, Port Louis or Saint-Pierre?
Port Louis, with roughly 82,302 trees inside its 2 km radius against 78,451. Tree cover tells a slightly different story from raw count: Saint-Pierre has the denser canopy at 33.7%.
Which has better air quality, Port Louis or Saint-Pierre?
Port Louis right now, at AQI 16 against 20 — 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?
Port Louis needs about 4,029 more to reach its canopy target, and Saint-Pierre 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
- Port Louis vs Vacoas63% tree cover · AQI 17Compare
- Port Louis vs Bel Air Rivière Sèche83% tree cover · AQI 17Compare
- Port Louis vs Saint-Benoît54% tree cover · AQI 20Compare
- Port Louis vs Saint-Denis42% tree cover · AQI 24Compare
- Port Louis vs Saint-Leu45% tree cover · AQI 20Compare
- Port Louis vs Saint-Paul40% tree cover · AQI 20Compare
Build your own
Compare Port Louis with somewhere else
This place
Port Louis
Want a different pair? Browse comparisons or measure any address.