City report · England, United Kingdom
Harrow Air quality today
Air quality in Harrow currently reads AQI 52 (Moderate): Unusually sensitive people should consider limiting long outdoor exertion.
AQI 52
Air quality right now
Moderate
- PM2.5, fine particles (µg/m³)
- 9.5
- tree cover
- 28.9%
- trees in this area
- 90.8K
- more trees needed
- 3.5K
Measured across a 1.2 mi (2 km) radius around Harrow, 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.
Harrow · AQI 52 (Moderate)
Harrow's tree count comes to 90,792 trees across 4.9 sq mi (12.57 km²), 1 points below the 30% tree-cover level considered healthy for this area, so roughly 3,456 more trees would close the gap.
Air quality detail
Air quality in Harrow today: AQI 52, Moderate
Main pollutant: PM2.5 · Observed Nov 11, 16:00 local time via OpenAQ ground stations, US EPA index. Values in µg/m³.
Ground station · Brent - Ikea, 3.7 mi (5.9 km) away · median of 3 stations
Health signal
Unusually sensitive people should consider limiting long outdoor exertion.
PM2.5
9.5
PM10
23.0
NO₂
30.4
O₃
—
SO₂
—
CO
—
Data: OpenAQ · DEFRA, London Air Quality Network
- 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 Harrow's daily AQI at 74 on average, from 38 on Nov 4 to an hourly peak of 122 on Nov 6.
This is the US EPA AQI. How it differs from the UK's Daily Air Quality Index
Where Harrow stands: the most polluted cities in the world right now · the cleanest
Tree cover detail
Tree cover in Harrow: Below target
28.9% tree cover against a 30% healthy-neighborhood target, across 4.9 sq mi (12.57 km²).
Trees in this area
90,792
Target trees
94,248
More trees needed
3,456
CO₂ if planted / yr
76.0 t
Deforestation · 2001–2025
How much forest has Harrow lost?
Since 2001, the area within 10 km of Harrow has lost about 8 hectares of forest (about 12 football pitches): under 1% of the forest it had in 2000. The biggest cause was towns and roads (12%). Almost none of it was deforestation, meaning forest cleared for good.
2017: satellite photo from August 2017 of a 5 × 5 km area in the city center.
- Forest lost since 2001
- 8 haabout 12 football pitches
- Share of its forest
- under 1%of what there was in 2000
- Cleared for good
- under 1 hadeforestation: turned into farms, mines or towns
The worst year was 2006, when about 2 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 | 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 | 2 ha | 2 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 | under 1 ha | under 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 | 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 | 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 Harrow?
- Towns and roadscleared for good12% · 1 ha
- Loggingcan grow back7.2% · under 1 ha
- Unknown causescause unknown83% · 7 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
- 13,000 ha
- Forest in 2020
- 13,600 ha
- Overall change
- +620 hamore forest than in 2000
Comparing satellite maps from 2000 and 2020, the forest around Harrow grew from about 13,000 hectares to 13,600 hectares, a net gain of about 620 hectares (+4.8%). New forest grew on about 670 hectares, while 50 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 Harrow
Same 2 km radius, same index — so they compare directly.
- London16.2 km
United Kingdom
- Tree cover
- 18%
- Air quality
- 56
- Enfield Town18.9 km
United Kingdom
- Tree cover
- 31%
- Air quality
- 76
- Slough19.8 km
United Kingdom
- Tree cover
- 21%
- Air quality
- 57
- Walthamstow21.6 km
United Kingdom
- Tree cover
- 22%
- Air quality
- 81
- Sutton27.0 km
United Kingdom
- Tree cover
- 45%
- Air quality
- 71
- Barking29.2 km
United Kingdom
- Tree cover
- 16%
- Air quality
- 56
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Frequently asked
Questions about Harrow
What is the air quality (AQI) in Harrow right now?
The latest reading for Harrow shows an AQI of 52 (Moderate), measured Nov 11, 16:00 local time by 3 ground monitoring stations via OpenAQ (the median of their readings; the nearest is Brent - Ikea, 3.7 mi (5.9 km) away). The main pollutant is PM2.5. Unusually sensitive people should consider limiting long outdoor exertion.
Is it safe to exercise outside in Harrow today?
At AQI 52 (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 Harrow been like this week?
Over the last 7 days, the CAMS air-quality model put Harrow's daily AQI at 74 on average, from 38 on Nov 4 to an hourly peak of 122 on Nov 6. No day averaged above 100, the level where the air turns unhealthy for sensitive groups.
Is Harrow'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 Harrow lost since 2001?
Since 2001, the area within 10 km of Harrow has lost about 8 hectares of forest (about 12 football pitches): under 1% of the forest it had in 2000. The biggest cause was towns and roads (12%). Almost none of it was deforestation, meaning forest cleared for good. Comparing satellite maps from 2000 and 2020, the forest around Harrow grew from about 13,000 hectares to 13,600 hectares, a net gain of about 620 hectares (+4.8%). New forest grew on about 670 hectares, while 50 hectares were lost.
What is the tree count in Harrow?
Harrow has an estimated 90,792 trees across the 4.9 sq mi (12.57 km²) measured — 28.9% tree cover, 1 percentage points short of the 30% tree-cover target set for this area.
How many more trees does Harrow need?
Harrow needs roughly 3,456 more trees to close a 1-point shortfall against its 30% tree-cover target — about 76.0 t of extra CO₂ absorbed per year once grown.
How are Harrow's air quality and tree cover measured?
Air quality is measured by ground monitoring stations near Harrow, 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 Harrow; the tree count is an estimate derived from that cover.
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