City report · England, United Kingdom
Watford Air quality today
Air quality in Watford currently reads AQI 55 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 55
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 11.5
- tree cover
- 30.2%
- trees in this area
- 94.9K
- more trees needed
- 0
Measured across a 1.2 mi (2 km) radius around Watford, 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.
Watford · AQI 55 (Moderate)
Watford's tree count comes to 94,876 trees across 4.9 sq mi (12.57 km²), already at or above the 30% tree-cover level considered healthy for this area.
Air quality detail
Air quality in Watford today: AQI 55, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 16:00 local time via OpenAQ and World Air Quality Index Project ground stations, US EPA index. Values in µg/m³.
Ground station · Brent - Ikea, 9.3 mi (14.9 km) away · median of 10 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
11.5
PM10
22.0
NO₂
27.6
O₃
—
SO₂
—
CO
—
Data: OpenAQ · DEFRA, London Air Quality Network, World Air Quality Index Project, UK-AIR, air quality information resource - Defra, UK, London Air Quality Network - Environmental Research Group, King's College London
- 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 Watford's daily AQI at 71 on average, from 36 on Nov 4 to an hourly peak of 97 on Nov 6.
This is the US EPA AQI. How it differs from the UK's Daily Air Quality Index
Where Watford stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Watford: Healthy tree cover
30.2% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
94,876
Target trees
94,876
More trees needed
0
CO₂ if planted / yr
0 kg
Deforestation · 2001–2025
How much forest has Watford lost?
Since 2001, the area within 10 km of Watford has lost about 48 hectares of forest (about 67 football pitches): under 1% of the forest it had in 2000. Most of it was lost to logging, so much of it can grow back. About 3 hectares (5.4%) was deforestation: forest cleared for good for farms, mines or towns.
2017: satellite photo from August 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 48 haabout 67 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 2021, when about 16 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 | under 1 ha | under 1 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 | 4 ha | 4 ha |
| 2007 | under 1 ha | under 1 ha | under 1 ha |
| 2008 | under 1 ha | 4 ha | 4 ha |
| 2009 | under 1 ha | under 1 ha | under 1 ha |
| 2010 | under 1 ha | 3 ha | 3 ha |
| 2011 | under 1 ha | under 1 ha | under 1 ha |
| 2012 | under 1 ha | 2 ha | 2 ha |
| 2013 | under 1 ha | 2 ha | 2 ha |
| 2014 | 1 ha | 5 ha | 6 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 | under 1 ha | under 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 | 16 ha | 16 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 | 7 ha | 7 ha |
| 2025 | under 1 ha | under 1 ha | under 1 ha |
What is causing deforestation around Watford?
- Loggingcan grow back67% · 32 ha
- Towns and roadscleared for good5.6% · 3 ha
- Unknown causescause unknown27% · 13 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
- 13,200 ha
- Forest in 2020
- 13,900 ha
- Overall change
- +637 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Watford grew from about 13,200 hectares to 13,900 hectares, a net gain of about 637 hectares (+4.8%). New forest grew on about 692 hectares, while 55 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 Watford
Same 2 km radius, same index — so they compare directly.
- Slough21.3 km
United Kingdom
- Tree cover
- 21%
- Air quality
- 57
- Enfield Town21.5 km
United Kingdom
- Tree cover
- 31%
- Air quality
- 76
- High Wycombe24.6 km
United Kingdom
- Tree cover
- 41%
- Air quality
- 83
- London24.8 km
United Kingdom
- Tree cover
- 18%
- Air quality
- 56
- Luton25.0 km
United Kingdom
- Tree cover
- 24%
- Air quality
- 65
- Walthamstow26.9 km
United Kingdom
- Tree cover
- 22%
- Air quality
- 81
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Frequently asked
Questions about Watford
What is the air quality (AQI) in Watford right now?
The latest reading for Watford shows an AQI of 55 (Moderate), measured Nov 11, 16:00 local time by 10 ground monitoring stations via OpenAQ (the median of their readings; the nearest is Brent - Ikea, 9.3 mi (14.9 km) away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Watford today?
At AQI 55 (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 Watford been like this week?
Over the last 7 days, the CAMS air-quality model put Watford's daily AQI at 71 on average, from 36 on Nov 4 to an hourly peak of 97 on Nov 6. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Watford'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 Watford lost since 2001?
Since 2001, the area within 10 km of Watford has lost about 48 hectares of forest (about 67 football pitches): under 1% of the forest it had in 2000. Most of it was lost to logging, so much of it can grow back. About 3 hectares (5.4%) was deforestation: forest cleared for good for farms, mines or towns. Comparing satellite maps from 2000 and 2020, the forest around Watford grew from about 13,200 hectares to 13,900 hectares, a net gain of about 637 hectares (+4.8%). New forest grew on about 692 hectares, while 55 hectares were lost.
What is the tree count in Watford?
Watford has an estimated 94,876 trees across the 4.9 sq mi (12.57 km²) measured — 30.2% tree cover, already past the 30% tree-cover target set for this area.
How many more trees does Watford need?
Watford has already reached its tree-cover target, so no additional trees are needed to close the gap.
How are Watford's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Watford, 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 Watford; the tree count is an estimate derived from that cover.
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