When discussing life safety, most conversations focus on visible threats such as fire, smoke, electrical faults and carbon monoxide. However, alongside all of these threats, one of the UK's most serious environmental hazards cannot be seen, smelt or tasted.

Radon is a naturally occurring radioactive gas that can accumulate within homes, workplaces, schools and public buildings. Long-term exposure to elevated levels can increase the risk of lung cancer, making radon one of the most significant hidden health risks affecting buildings across the UK.

Each year, it’s estimated to be the cause of 1,100 deaths* across the UK. For reference, for 2025, total road accident related deaths were 1,556 in Great Britain.

What is radon?

Radon is a radioactive gas that forms naturally when uranium found in rocks and soils breaks down underground. Every property contains some level of radon, but concentrations vary considerably depending on local geology.

Outdoors, radon disperses quickly and generally poses little risk. Problems arise when the gas enters buildings and becomes trapped, allowing levels to build up over time. It then becomes an invisible killer.

Radon can enter through:

• Cracks in concrete floors
• Construction joints
• Gaps around service pipes and cables
• Drainage systems
• Wall and floor junctions
• Sub-floor voids and crawl spaces

Why is Radon dangerous?

Unlike fires or carbon monoxide leaks, radon exposure produces no immediate warning signs. The health effects develop gradually, often over many years. This then makes it vital to monitor radon levels early to target it early.

When inhaled, radioactive particles released by radon can damage lung tissue. Long-term exposure increases the risk of lung cancer, particularly amongst smokers and former smokers.

Is Radon a UK wide issue?

Yes. While some areas are more susceptible due to underlying geology, radon exists throughout the UK. Elevated readings can occur in both urban and rural locations and cannot be predicted simply by looking at a property.

The UK Health Security Agency's Radon Map allows homeowners and businesses to check whether their property falls within a radon-affected area. See links below.

How can Radon risks be reduced?

The most effective strategy is to prevent radon from entering a building in the first place. Where elevated levels already exist, the objective is to reduce indoor concentrations as far as reasonably practicable and ideally well below the UK Action Level of 200 Bq/m³.

High radon levels are typically caused by air containing the gas being drawn from the soil beneath a property through cracks, gaps and service penetrations in floors and foundations. This movement is driven by pressure differences between the building and the surrounding ground.

Fortunately, there are a range of proven mitigation measures capable of significantly reducing exposure levels.

• Reducing pressure differences between the building and the ground beneath it.
• Sealing cracks and service penetrations that allow radon-bearing air to enter.
• Installing radon sumps to safely extract radon from beneath the building.
• Improving sub-floor ventilation to disperse radon before it enters occupied spaces.
• Enhancing internal ventilation where appropriate to dilute indoor concentrations.

Steps to managing radon risks

A hidden risk worth understanding

Fire safety, carbon monoxide protection and emergency preparedness remain essential aspects of modern building management. However, radon highlights the importance of considering less obvious environmental hazards that can affect occupant wellbeing over the long term.

By increasing awareness, promoting testing and supporting informed risk assessment, organisations can contribute towards creating healthier and safer environments for everyone who lives, works and learns within them.

Radon falls within the Radiation hazard under the HHSRS (Housing Health and Safety Rating System). As a result, it will be covered by Phase 3 of Awaab’s Law in England. This is currently expected to come into force in 2027.