Radon Risk in Hertfordshire

Last reviewed: March 2026 · Data: BGS Indicative Atlas v3.

50 postcode districts · 10 classified High or above · Average risk class: 1.9 / 5

Radon is a naturally occurring radioactive gas and the second largest cause of lung cancer in the UK. Risk varies significantly by location — the areas below show how Hertfordshire compares. 10 districts in Hertfordshire are classified High risk or above — testing is strongly recommended in these areas.

All Districts in Hertfordshire

District Risk Level % Homes
WD4 Very High 5–10%
WD5 Very High 5–10%
AL3 High 3–5%
AL5 High 3–5%
HP2 High 3–5%
HP3 High 3–5%
HP4 High 3–5%
WD17 High 3–5%
WD25 High 3–5%
WD7 High 3–5%
AL10 Moderate 1–3%
AL4 Moderate 1–3%
AL6 Moderate 1–3%
AL8 Moderate 1–3%
CM23 Moderate 1–3%
EN11 Moderate 1–3%
HP1 Moderate 1–3%
SG1 Moderate 1–3%
SG10 Moderate 1–3%
SG11 Moderate 1–3%
SG2 Moderate 1–3%
SG3 Moderate 1–3%
SG4 Moderate 1–3%
SG5 Moderate 1–3%
SG9 Moderate 1–3%
WD1 Moderate 1–3%
WD18 Moderate 1–3%
WD19 Moderate 1–3%
WD2 Moderate 1–3%
WD24 Moderate 1–3%
WD3 Moderate 1–3%
WD99 Moderate 1–3%
AL1 Low <1%
AL2 Low <1%
AL7 Low <1%
AL9 Low <1%
CM21 Low <1%
EN10 Low <1%
EN6 Low <1%
EN7 Low <1%
EN8 Low <1%
HP23 Low <1%
SG12 Low <1%
SG13 Low <1%
SG14 Low <1%
SG6 Low <1%
SG7 Low <1%
SG8 Low <1%
WD23 Low <1%
WD6 Low <1%

Get a Radon Test for Hertfordshire

The only way to know your home's radon level is to test. Radon levels in Hertfordshire are classified as Moderate — a test takes 3 months and costs around £29.

UKRadon Postal Test Kit
From ~£29 · 3-month detector Airthings Corentium Home (Amazon UK)
~£99 · Digital · Ongoing monitoring

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