City report · Sierra Leone
Koidu Air quality today
Air quality in Koidu currently reads AQI 74 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
Air quality right now
AQI 74
Moderate
- PM2.5, fine particles (µg/m³)
- 20.7
- tree cover
- 37.7%
- trees in this area
- 118K
- more trees needed
- 0
Measured across a 2 km radius around Koidu, Sierra Leone (12.57 km²), from a satellite image of May 2, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Koidu · AQI 74 (Moderate)
Koidu's tree count comes to 118,438 trees across 12.57 km², already at or above the 30% tree-cover level considered healthy for this area.
Air quality detail
Air quality in Koidu today: AQI 74, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 08:00 local time via Open-Meteo / CAMS, US EPA index. Values in µg/m³.
Model estimate · no ground station nearby
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
20.7
PM10
32.9
NO₂
4.1
O₃
44.0
SO₂
0.4
CO
198.0
- Outdoor exercise
- Fine for most people; unusually sensitive people should take long or hard exercise easier
- Windows
- Fine to open; close them if you are sensitive to pollution
- Mask
- Not needed for most people
- Air purifier
- Worth running if you are sensitive
Over the last 7 days, the CAMS air-quality model put Koidu's daily AQI at 60 on average, from 49 on Nov 8 to an hourly peak of 85 on Nov 10.
Where Koidu stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Koidu: Healthy tree cover
37.7% tree cover against a 30% healthy-neighborhood target, across 12.57 km².
Trees in this area
118,438
Target trees
118,438
More trees needed
0
CO₂ if planted / yr
0 kg
Deforestation · 2001–2025
How much forest has Koidu lost?
Since 2001, the area within 10 km of Koidu has lost about 6,180 hectares of forest (about 8,600 football pitches): 32% of the forest it had in 2000. Most of it was lost to shifting farming, so much of it can grow back. About 1,400 hectares (23%) was deforestation: forest cleared for good for farms, mines or towns.
2017: satellite photo from March 2017 of a 5 × 5 km area about 7 km north of the city center.
- Forest lost since 2001
- 6,180 haabout 8,600 football pitches
- Share of its forest
- 32%of what there was in 2000
- Cleared for good
- 1,400 hadeforestation: turned into farms, mines or towns
Forest loss has stayed about the same: about 311 hectares a year in 2021–2025, against 356 hectares a year in 2016–2020. The worst year was 2006, when about 533 hectares of forest were lost.
Hectares of forest lost each year
Show the figures as a table
| Year | Cleared for good | Can grow back | Total |
|---|---|---|---|
| 2001 | 31 ha | 27 ha | 58 ha |
| 2002 | 62 ha | 37 ha | 98 ha |
| 2003 | 11 ha | 9 ha | 19 ha |
| 2004 | 7 ha | 9 ha | 16 ha |
| 2005 | 31 ha | 28 ha | 58 ha |
| 2006 | 280 ha | 253 ha | 533 ha |
| 2007 | 147 ha | 342 ha | 489 ha |
| 2008 | 82 ha | 245 ha | 327 ha |
| 2009 | 28 ha | 175 ha | 203 ha |
| 2010 | 15 ha | 37 ha | 53 ha |
| 2011 | 28 ha | 32 ha | 60 ha |
| 2012 | 2 ha | 22 ha | 24 ha |
| 2013 | 50 ha | 331 ha | 381 ha |
| 2014 | 35 ha | 217 ha | 252 ha |
| 2015 | 31 ha | 240 ha | 271 ha |
| 2016 | 46 ha | 275 ha | 321 ha |
| 2017 | 68 ha | 387 ha | 455 ha |
| 2018 | 42 ha | 319 ha | 361 ha |
| 2019 | 59 ha | 273 ha | 331 ha |
| 2020 | 57 ha | 255 ha | 312 ha |
| 2021 | 44 ha | 190 ha | 234 ha |
| 2022 | 96 ha | 356 ha | 452 ha |
| 2023 | 56 ha | 228 ha | 284 ha |
| 2024 | 57 ha | 270 ha | 327 ha |
| 2025 | 34 ha | 223 ha | 256 ha |
What is causing deforestation around Koidu?
- Shifting farmingcan grow back77% · 4,780 ha
- Farms, pasture and plantationscleared for good11% · 700 ha
- Towns and roadscleared for good7.2% · 444 ha
Also: mining and energy.
Causes for 2025 are estimates, based on what caused forest loss in the same places up to 2024.
Forest gained and lost, 2000–2020
- Forest in 2000
- 25,200 ha
- Forest in 2020
- 22,900 ha
- Overall change
- −2,350 haless forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Koidu shrank from about 25,200 hectares to 22,900 hectares, a net loss of about 2,350 hectares (−9.3%). New forest grew on about 131 hectares, but 2,480 hectares were lost.
These 2000 and 2020 maps, from the University of Maryland, count any land with trees taller than 5 m as forest, including plantations and orchards. Forest that was cut or burned and had grown back by 2020 counts in both years, so the loss here is smaller than the yearly figures.
These figures cover everything within 10 km of the city center, a wider area than the report above, because forest is usually lost at a city's edges.
Source: Hansen/UMD/Google/USGS/NASA, Global Forest Change (GFC-2025-v1.13); causes: WRI/Google DeepMind drivers of forest loss; both CC BY 4.0, summed by Airleaf for each area. Forest gained and lost 2000–2020: Potapov et al. 2022, UMD GLAD Global Land Cover and Land Use Change, CC BY 4.0. Images: contains modified Copernicus Sentinel data. How it's measured
In the same region
Measured cities near Koidu
Same 2 km radius, same index — so they compare directly.
- Kissidougou113.1 km
Guinea
- Tree cover
- 29%
- Air quality
- 72
- Bo113.2 km
Sierra Leone
- Tree cover
- 22%
- Air quality
- 93
- Makeni120.9 km
Sierra Leone
- Tree cover
- 13%
- Air quality
- 91
- Kakata244.6 km
Liberia
- Tree cover
- 34%
- Air quality
- 40
- Gbarnga246.8 km
Liberia
- Tree cover
- 48%
- Air quality
- 31
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Frequently asked
Questions about Koidu
What is the air quality (AQI) in Koidu right now?
The latest reading for Koidu shows an AQI of 74 (Moderate), observed Nov 11, 08:00 local time via Open-Meteo / CAMS, US EPA index. The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Koidu today?
At AQI 74 (Moderate): fine for most people; unusually sensitive people should take long or hard exercise easier. Windows: fine to open; close them if you are sensitive to pollution. Masks: not needed for most people. The reading changes through the day, so check again before a long run or ride.
What has the air quality in Koidu been like this week?
Over the last 7 days, the CAMS air-quality model put Koidu's daily AQI at 60 on average, from 49 on Nov 8 to an hourly peak of 85 on Nov 10. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
How much forest has the area around Koidu lost since 2001?
Since 2001, the area within 10 km of Koidu has lost about 6,180 hectares of forest (about 8,600 football pitches): 32% of the forest it had in 2000. Most of it was lost to shifting farming, so much of it can grow back. About 1,400 hectares (23%) was deforestation: forest cleared for good for farms, mines or towns. Forest loss has stayed about the same: about 311 hectares a year in 2021–2025, against 356 hectares a year in 2016–2020. Comparing satellite maps from 2000 and 2020, the forest around Koidu shrank from about 25,200 hectares to 22,900 hectares, a net loss of about 2,350 hectares (−9.3%). New forest grew on about 131 hectares, but 2,480 hectares were lost.
What is the tree count in Koidu?
Koidu has an estimated 118,438 trees across the 12.57 km² measured — 37.7% tree cover, already past the 30% tree-cover target set for this area.
How many more trees does Koidu need?
Koidu has already reached its tree-cover target, so no additional trees are needed to close the gap.
How are Koidu's air quality and tree cover measured?
Air quality comes from ground monitoring stations via OpenAQ where one reports nearby, and otherwise, as here, from the Open-Meteo / CAMS model, which may differ from street-level monitors. Tree cover is measured from Sentinel-2 L2A (ESA Copernicus) via Earth Search satellite imagery at 10 m detail across a 2 km radius around Koidu; the tree count is an estimate derived from that cover.
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