City report · England, United Kingdom
Colchester Air quality today
Air quality in Colchester currently reads AQI 64 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 64
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 14.8
- tree cover
- 29.3%
- trees in this area
- 92.0K
- more trees needed
- 2.2K
Measured across a 1.2 mi (2 km) radius around Colchester, UK (4.9 sq mi), from a satellite image of Aug 25, 2026. Lower AQI is better: 0–50 is Good, above 300 is Hazardous.
Colchester · AQI 64 (Moderate)
Colchester's tree count comes to 92,049 trees across 4.9 sq mi (12.57 km²), 1 points below the 30% tree-cover level considered healthy for this area, so roughly 2,199 more trees would close the gap.
Air quality detail
Air quality in Colchester today: AQI 64, Moderate
Main pollutant: PM2.5 · Observed Nov 10, 10:00 local time via Open-Meteo / CAMS, corrected with 10 ground-station cities within 85 km, US EPA index. Values in µg/m³.
Estimate · model corrected with 10 station cities within 52.8 mi (85 km), e.g. Chelmsford and Southend-on-Sea
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
14.8
PM10
20.1
NO₂
9.4
O₃
55.0
SO₂
1.3
CO
195.0
- 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 Colchester's daily AQI at 64 on average, from 27 on Nov 4 to an hourly peak of 81 on Nov 7.
This is the US EPA AQI. How it differs from the UK's Daily Air Quality Index
Where Colchester stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Colchester: Below target
29.3% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
92,049
Target trees
94,248
More trees needed
2,199
CO₂ if planted / yr
48.4 t
Deforestation · 2001–2025
How much forest has Colchester lost?
Since 2001, the area within 10 km of Colchester has lost about 16 hectares of forest (about 22 football pitches): under 1% of the forest it had in 2000. The biggest cause was logging (38%), after which forest can grow back. About 4 hectares (25%) was deforestation: forest cleared for good for farms, mines or towns.
2017: satellite photo from July 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 16 haabout 22 football pitches
- Share of its forest
- under 1%of what there was in 2000
- Cleared for good
- 4 hadeforestation: turned into farms, mines or towns
The worst year was 2006, when about 3 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 | under 1 ha | 1 ha | 1 ha |
| 2002 | under 1 ha | 1 ha | 1 ha |
| 2003 | under 1 ha | under 1 ha | under 1 ha |
| 2004 | under 1 ha | under 1 ha | 1 ha |
| 2005 | under 1 ha | 1 ha | 2 ha |
| 2006 | under 1 ha | 2 ha | 3 ha |
| 2007 | under 1 ha | under 1 ha | under 1 ha |
| 2008 | under 1 ha | 2 ha | 2 ha |
| 2009 | under 1 ha | under 1 ha | under 1 ha |
| 2010 | under 1 ha | under 1 ha | under 1 ha |
| 2011 | under 1 ha | under 1 ha | under 1 ha |
| 2012 | under 1 ha | 1 ha | 1 ha |
| 2013 | under 1 ha | under 1 ha | under 1 ha |
| 2014 | under 1 ha | under 1 ha | under 1 ha |
| 2015 | under 1 ha | under 1 ha | under 1 ha |
| 2016 | 1 ha | under 1 ha | 1 ha |
| 2017 | 1 ha | under 1 ha | 2 ha |
| 2018 | under 1 ha | under 1 ha | under 1 ha |
| 2019 | under 1 ha | under 1 ha | under 1 ha |
| 2020 | under 1 ha | under 1 ha | under 1 ha |
| 2021 | under 1 ha | under 1 ha | under 1 ha |
| 2022 | under 1 ha | under 1 ha | under 1 ha |
| 2023 | under 1 ha | under 1 ha | under 1 ha |
| 2024 | under 1 ha | under 1 ha | under 1 ha |
| 2025 | under 1 ha | under 1 ha | under 1 ha |
What is causing deforestation around Colchester?
- Loggingcan grow back38% · 6 ha
- Towns and roadscleared for good26% · 4 ha
- Unknown causescause unknown36% · 6 ha
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
- 4,140 ha
- Forest in 2020
- 4,690 ha
- Overall change
- +551 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Colchester grew from about 4,140 hectares to 4,690 hectares, a net gain of about 551 hectares (+13%). New forest grew on about 594 hectares, while 43 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 Colchester
Same 2 km radius, same index — so they compare directly.
- Ipswich25.6 km
United Kingdom
- Tree cover
- 31%
- Air quality
- 57
- Chelmsford34.4 km
United Kingdom
- Tree cover
- 24%
- Air quality
- 51
- Southend-on-Sea41.2 km
United Kingdom
- Tree cover
- 16%
- Air quality
- 56
- Basildon47.1 km
United Kingdom
- Tree cover
- 31%
- Air quality
- 51
- Gillingham60.8 km
United Kingdom
- Tree cover
- 23%
- Air quality
- 56
- Cambridge64.0 km
United Kingdom
- Tree cover
- 30%
- Air quality
- 46
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Frequently asked
Questions about Colchester
What is the air quality (AQI) in Colchester right now?
The latest reading for Colchester shows an AQI of 64 (Moderate), observed Nov 10, 10:00 local time via Open-Meteo / CAMS, corrected with 10 ground-station cities within 85 km, 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 Colchester today?
At AQI 64 (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 Colchester been like this week?
Over the last 7 days, the CAMS air-quality model put Colchester's daily AQI at 64 on average, from 27 on Nov 4 to an hourly peak of 81 on Nov 7. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Colchester's AQI the same as the UK's Daily Air Quality Index?
No. Airleaf shows the US EPA Air Quality Index (AQI), the scale used by IQAir and most air-quality apps. The UK's Daily Air Quality Index (DAQI), published by Defra, runs from 1 to 10: 1–3 low, 4–6 moderate, 7–9 high and 10 very high. It is a different scale altogether, so a US AQI figure can't be read on it directly; both, though, are built from the same main pollutants, with fine particles (PM2.5) usually the one that decides the reading.
How much forest has the area around Colchester lost since 2001?
Since 2001, the area within 10 km of Colchester has lost about 16 hectares of forest (about 22 football pitches): under 1% of the forest it had in 2000. The biggest cause was logging (38%), after which forest can grow back. About 4 hectares (25%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Colchester grew from about 4,140 hectares to 4,690 hectares, a net gain of about 551 hectares (+13%). New forest grew on about 594 hectares, while 43 hectares were lost.
What is the tree count in Colchester?
Colchester has an estimated 92,049 trees across the 4.9 sq mi (12.57 km²) measured — 29.3% tree cover, 1 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Colchester need?
Colchester needs roughly 2,199 more trees to close a 1-point shortfall against its 30% tree-cover target — about 48.4 t of extra CO₂ absorbed per year once grown.
How are Colchester'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 1.2 mi (2 km) radius around Colchester; the tree count is an estimate derived from that cover.
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