What's the air quality in North Hertfordshire? NO₂ 9.7 µg/m³
In 2025 the average resident of North Hertfordshire lived with background NO₂ of 9.7 µg/m³, Very High for England and Wales and about the WHO guideline of 10. PM2.5 was 8.3 µg/m³, Very High for England and Wales and 1.7 times the WHO guideline of 5. The typical area in England and Wales has NO₂ of 7.2 and PM2.5 of 7.4 µg/m³.
- PM2.5
- 8.3 µg/m³
- NO₂ for England and Wales
- Very High
- Figures for
- 2025 annual average
Modelled background levels averaged over where residents live (Census 2021), not roadside levels. Contains public sector information licensed under the Open Government Licence v3.0. Source: Defra modelled background pollution, 2025. How we calculate this
All house prices in North HertfordshireIs the air quality good in North Hertfordshire?
Background NO₂ in North Hertfordshire is 9.7 µg/m³, about the WHO guideline of 10, and higher than the typical area (7.2). That puts it in the Very High band. Background PM2.5 in North Hertfordshire is 8.3 µg/m³, 1.7 times the WHO guideline of 5, and higher than the typical area (7.4). That puts it in the Very High band. Most of England and Wales is above the WHO guideline for PM2.5, so the bands compare places with each other rather than giving a pass or fail.
Nitrogen dioxide (NO₂): 9.7 µg/m³
NO₂ level is Very High, on a scale from Very Low to Very High.
Very High means the highest fifth of areas in England and Wales for NO₂.
| Very Low | up to 4.7 |
|---|---|
| Low | 4.7 to 6.5 |
| Typical | 6.5 to 7.7 |
| High | 7.7 to 9.2 |
| Very High | over 9.2 |
WHO guideline: 10 µg/m³ (in the Very High band). UK legal limit: 40 µg/m³.
Fine particles (PM2.5): 8.3 µg/m³
PM2.5 level is Very High, on a scale from Very Low to Very High.
Very High means the highest fifth of areas in England and Wales for PM2.5.
| Very Low | up to 6.0 |
|---|---|
| Low | 6.0 to 7.2 |
| Typical | 7.2 to 7.7 |
| High | 7.7 to 8.2 |
| Very High | over 8.2 |
WHO guideline: 5 µg/m³ (in the Very Low band). UK legal limit: 20 µg/m³, with a target of 10 µg/m³ in England by 2040.
The bands split every area we cover into fifths by its level, from Very Low to Very High. The map uses the same colours.
Which part of North Hertfordshire has the cleanest air?
Nuthampstead has the lowest background NO₂ of the 34 areas of North Hertfordshire, at 7.5 µg/m³. Knebworth has the highest, at 11.1 µg/m³. Average house prices are shown alongside, so you can weigh air quality against cost.
| Area | NO₂ | PM2.5 | NO₂ band | Average price |
|---|---|---|---|---|
| NuthampsteadTypical | 7.5 | 8.0 | Typical | — |
| BarkwayTypical | 7.6 | 8.0 | Typical | £507,516 |
| BarleyTypical | 7.6 | 8.1 | Typical | £442,500 |
| TherfieldTypical | 7.7 | 8.1 | Typical | £562,500 |
| ReedHigh | 7.7 | 8.1 | High | £752,500 |
| KelshallHigh | 7.8 | 8.1 | High | — |
| SandonHigh | 7.8 | 8.1 | High | £870,000 |
| RushdenHigh | 8.0 | 8.2 | High | £720,000 |
| WallingtonHigh | 8.1 | 8.1 | High | £410,000 |
| HextonHigh | 8.2 | 8.0 | High | £950,000 |
| AshwellHigh | 8.2 | 8.2 | High | £525,607 |
| PirtonHigh | 8.4 | 8.1 | High | £676,300 |
| HinxworthHigh | 8.6 | 8.2 | High | £807,500 |
| NewnhamHigh | 8.6 | 8.3 | High | — |
| ClothallHigh | 8.6 | 8.2 | High | — |
| WestonHigh | 8.9 | 8.2 | High | £681,718 |
| Great AshbyHigh | 9.0 | 8.2 | High | £397,878 |
| LilleyHigh | 9.1 | 8.0 | High | £630,083 |
| HolwellHigh | 9.1 | 8.2 | High | £561,500 |
| BygraveHigh | 9.1 | 8.3 | High | £743,750 |
| RoystonHigh | 9.1 | 8.3 | High | £388,568 |
| IcklefordVery High | 9.2 | 8.2 | Very High | £456,040 |
| PrestonVery High | 9.5 | 8.2 | Very High | £1,048,750 |
| OffleyVery High | 9.6 | 8.2 | Very High | £622,192 |
| St Paul's WaldenVery High | 9.7 | 8.2 | Very High | £648,403 |
| CodicoteVery High | 9.9 | 8.3 | Very High | £608,408 |
| KimptonVery High | 10.0 | 8.3 | Very High | £867,363 |
| RadwellVery High | 10.0 | 8.3 | Very High | — |
| LangleyVery High | 10.1 | 8.2 | Very High | £870,000 |
| St IppolytsVery High | 10.1 | 8.3 | Very High | £845,009 |
| WymondleyVery High | 10.5 | 8.3 | Very High | £558,863 |
| King's WaldenVery High | 10.8 | 8.2 | Very High | £684,800 |
| GraveleyVery High | 10.9 | 8.3 | Very High | £551,125 |
| KnebworthVery High | 11.1 | 8.4 | Very High | £463,372 |
Levels in µg/m³, 2025 annual average.
How does air quality in North Hertfordshire compare with nearby areas?
Background NO₂ in North Hertfordshire compared with the 6 nearest other areas in Hertfordshire.
North Hertfordshire vs Stevenage
- North Hertfordshire
- NO₂ 9.7 µg/m³
- Stevenage
- NO₂ 11.0 µg/m³
Open comparison
North Hertfordshire vs East Hertfordshire
- North Hertfordshire
- NO₂ 9.7 µg/m³
- East Hertfordshire
- NO₂ 10.9 µg/m³
Open comparison
North Hertfordshire vs Welwyn Hatfield
- North Hertfordshire
- NO₂ 9.7 µg/m³
- Welwyn Hatfield
- NO₂ 12.2 µg/m³
Open comparison
North Hertfordshire vs St Albans
- North Hertfordshire
- NO₂ 9.7 µg/m³
- St Albans
- NO₂ 12.4 µg/m³
Open comparison
North Hertfordshire vs Broxbourne
- North Hertfordshire
- NO₂ 9.7 µg/m³
- Broxbourne
- NO₂ 13.0 µg/m³
Open comparison
North Hertfordshire vs Hertsmere
- North Hertfordshire
- NO₂ 9.7 µg/m³
- Hertsmere
- NO₂ 12.6 µg/m³
Open comparison
Does this include busy roads?
No. These are background levels: yearly averages over 1 km squares, away from the immediate influence of roads. Right beside a busy road in North Hertfordshire, NO₂ can be much higher. Councils publish roadside monitoring in their annual air quality reports.
What else do people ask about North Hertfordshire?
More quick answers on house prices, sales, areas, green space, crime, air quality and listed buildings in North Hertfordshire.
- What is the average house price in North Hertfordshire?
- When did average house prices in North Hertfordshire reach their peak?
- How many properties are being sold in North Hertfordshire?
- What type of properties are sold in North Hertfordshire?
- What price range do most homes sell for in North Hertfordshire?
- What is the most expensive (and cheapest) area of North Hertfordshire?
- How many parks and green spaces are in North Hertfordshire?
- What is the crime rate in North Hertfordshire?
- How many listed buildings are in North Hertfordshire?
- How do North Hertfordshire house prices compare with another area?
Where does this data come from?
Price information is from HM Land Registry, location boundaries are from OpenStreetMap, and households and population are from Nomis Census 2021 postcode estimates (21 March 2021). Parks and green space are from OS Open Greenspace. Contains OS data © Crown copyright and database right 2026. Crime is from police.uk street-level data. Contains public sector information licensed under the Open Government Licence v3.0. Source: police.uk. Listed buildings and scheduled monuments are from Historic England and Cadw, and conservation areas from planning.data.gov.uk. © Historic England 2026. Contains Ordnance Survey data © Crown copyright and database right 2026. Source: planning.data.gov.uk, Open Government Licence v3.0. Air quality is from Defra modelled background pollution maps. Contains public sector information licensed under the Open Government Licence v3.0. Source: Defra modelled background pollution, 2025.
Last updated 11 November 2026 at 01:27 with the latest Land Registry data (September 2026). The North Hertfordshire dataset covers 5,682 postcodes.
Contains HM Land Registry data © Crown copyright and database right 2026. This data is licensed under the Open Government Licence v3.0.
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