Diourbel vs Saint-Louis
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.
Diourbel has more tree cover — 33.3% against 4.3%.
Saint-Louis has cleaner air right now — AQI 19 against 21.
- Tree cover gap
- 29.0 points
- Diourbel is ahead.
- Air quality gap
- 2 AQI
- Saint-Louis is cleaner.
- Trees between them
- 95.7K
- Diourbel has more standing.
Senegal
Senegal
Tree cover
Share of the 2 km radius under canopy.
33.3%
4.3%
Air quality index
US EPA index, live, with its band. Lower is better.
21 · Good
19 · Good
Trees standing
Estimated from the measured canopy area.
105K
9.0K
Trees still needed
To reach the same canopy target. Fewer is better.
0
53.5K
CO₂ absorbed each year
By the trees already standing.
2.3M kg
197K 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. Diourbel is read from nearby ground stations and Saint-Louis is modelled — worth knowing, since the two are not quite like for like.
PM2.5
Fine particles, the pollutant that usually sets the index.
5 µg/m³
4.6 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 | Diourbel | Saint-Louis |
|---|---|---|
| 22 Sept | 112 | 107 |
| 23 Sept | 88 | 114 |
| 24 Sept | 17 | 29 |
| 25 Sept | 20 | 41 |
| 26 Sept | 34 | 70 |
| 27 Sept | 34 | 40 |
| 28 Sept | 25 | 23 |
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. Diourbel leads here at 33.3%.
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: Diourbel reads 21 (good) and Saint-Louis reads 19 (good) right now.
Frequently asked
Diourbel and Saint-Louis, answered
Which has more trees, Diourbel or Saint-Louis?
Diourbel, with roughly 104,615 trees inside its 2 km radius against 8,956. Tree cover tells a slightly different story from raw count: Diourbel has the denser canopy at 33.3%.
Which has better air quality, Diourbel or Saint-Louis?
Saint-Louis right now, at AQI 19 against 21 — a gap of 2 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?
Diourbel needs about 0 more to reach its canopy target, and Saint-Louis about 53,530. 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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