City report · England, United Kingdom
Chelmsford Air quality today
Air quality in Chelmsford currently reads AQI 51 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 51
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 9.1
- tree cover
- 24.4%
- trees in this area
- 76.7K
- more trees needed
- 17.6K
Measured across a 1.2 mi (2 km) radius around Chelmsford, 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.
Chelmsford · AQI 51 (Moderate)
Chelmsford's tree count comes to 76,655 trees across 4.9 sq mi (12.57 km²), 6 points below the 30% tree-cover level considered healthy for this area, so roughly 17,593 more trees would close the gap.
Air quality detail
Air quality in Chelmsford today: AQI 51, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 15:00 local time via World Air Quality Index Project ground stations, US EPA index. Values in µg/m³.
Ground station · Stanford-le-Hope Roadside, United Kingdom, 15.1 mi (24.3 km) away
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
9.1
PM10
10.8
NO₂
—
O₃
—
SO₂
—
CO
—
Data: World Air Quality Index Project, UK-AIR, air quality information resource - Defra, UK, London Air Quality Network - Environmental Research Group, King's College London, Air Quality in Kent and Medway
- 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 Chelmsford's daily AQI at 66 on average, from 31 on Nov 4 to an hourly peak of 89 on Nov 8.
This is the US EPA AQI. How it differs from the UK's Daily Air Quality Index
Where Chelmsford stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Chelmsford: Below target
24.4% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
76,655
Target trees
94,248
More trees needed
17,593
CO₂ if planted / yr
387.0 t
Deforestation · 2001–2025
How much forest has Chelmsford lost?
Since 2001, the area within 10 km of Chelmsford has lost about 15 hectares of forest (about 20 football pitches): under 1% of the forest it had in 2000. The biggest cause was logging (21%), after which forest can grow back. About 3 hectares (21%) was deforestation: forest cleared for good for farms, mines or towns.
2017: satellite photo from September 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 15 haabout 20 football pitches
- Share of its forest
- under 1%of what there was in 2000
- Cleared for good
- 3 hadeforestation: turned into farms, mines or towns
The worst year was 2002, 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 | under 1 ha | under 1 ha |
| 2002 | 2 ha | 1 ha | 3 ha |
| 2003 | under 1 ha | under 1 ha | under 1 ha |
| 2004 | under 1 ha | under 1 ha | under 1 ha |
| 2005 | under 1 ha | under 1 ha | under 1 ha |
| 2006 | under 1 ha | under 1 ha | under 1 ha |
| 2007 | under 1 ha | under 1 ha | under 1 ha |
| 2008 | under 1 ha | 2 ha | 3 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 | 2 ha | 3 ha |
| 2013 | under 1 ha | 1 ha | 1 ha |
| 2014 | under 1 ha | 1 ha | 1 ha |
| 2015 | under 1 ha | under 1 ha | under 1 ha |
| 2016 | under 1 ha | under 1 ha | under 1 ha |
| 2017 | under 1 ha | 1 ha | 1 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 Chelmsford?
- Loggingcan grow back21% · 3 ha
- Farms, pasture and plantationscleared for good17% · 2 ha
- Towns and roadscleared for good4.8% · under 1 ha
Also: unknown causes.
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
- 5,080 ha
- Forest in 2020
- 5,330 ha
- Overall change
- +247 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Chelmsford grew from about 5,080 hectares to 5,330 hectares, a net gain of about 247 hectares (+4.9%). New forest grew on about 308 hectares, while 61 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 Chelmsford
Same 2 km radius, same index — so they compare directly.
- Basildon18.6 km
United Kingdom
- Tree cover
- 31%
- Air quality
- 51
- Southend-on-Sea27.7 km
United Kingdom
- Tree cover
- 16%
- Air quality
- 56
- Colchester34.4 km
United Kingdom
- Tree cover
- 29%
- Air quality
- 64
- Barking34.9 km
United Kingdom
- Tree cover
- 16%
- Air quality
- 56
- Walthamstow37.5 km
United Kingdom
- Tree cover
- 22%
- Air quality
- 81
- Gillingham38.9 km
United Kingdom
- Tree cover
- 23%
- Air quality
- 56
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Frequently asked
Questions about Chelmsford
What is the air quality (AQI) in Chelmsford right now?
The latest reading for Chelmsford shows an AQI of 51 (Moderate), measured Nov 11, 15:00 local time by the Stanford-le-Hope Roadside, United Kingdom ground monitoring station, 15.1 mi (24.3 km) away, via OpenAQ. The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Chelmsford today?
At AQI 51 (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 Chelmsford been like this week?
Over the last 7 days, the CAMS air-quality model put Chelmsford's daily AQI at 66 on average, from 31 on Nov 4 to an hourly peak of 89 on Nov 8. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Chelmsford'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 Chelmsford lost since 2001?
Since 2001, the area within 10 km of Chelmsford has lost about 15 hectares of forest (about 20 football pitches): under 1% of the forest it had in 2000. The biggest cause was logging (21%), after which forest can grow back. About 3 hectares (21%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Chelmsford grew from about 5,080 hectares to 5,330 hectares, a net gain of about 247 hectares (+4.9%). New forest grew on about 308 hectares, while 61 hectares were lost.
What is the tree count in Chelmsford?
Chelmsford has an estimated 76,655 trees across the 4.9 sq mi (12.57 km²) measured — 24.4% tree cover, 6 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Chelmsford need?
Chelmsford needs roughly 17,593 more trees to close a 6-point shortfall against its 30% tree-cover target — about 387.0 t of extra CO₂ absorbed per year once grown.
How are Chelmsford's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Chelmsford, via OpenAQ; the 7-day trend is the Open-Meteo / CAMS model's estimate. 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 Chelmsford; the tree count is an estimate derived from that cover.
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