Research and analysis

HPR volume 13 issue 17: news (20 May)

Updated 20 December 2019

Reports on effectiveness of radon remediation measures published

The radioactive gas, radon, is the single largest source of radiation exposure to the UK population – in both homes and workplaces – the level of which is inherently linked to the indoor environment. Exposure to radon is the second most important cause of lung cancer, after tobacco smoking (with which it has a strong synergy), and a significant cause of lung cancer for non-smokers.

The effectiveness of PHE’s current general advice to homeowners on radon remediation, and the effectiveness of specific measures that have been requirements of Building Regulations since 1993, have been confirmed by two recent reports from the agency’s Centre for Radiation, Chemical and Environmental Hazards (CRCE) [1,2].

Since 1993 in the UK, new properties in many Radon Affected Areas [3] should be built with radon protection measures in place. For those with the highest probability of exceeding the radon Action Level [4], these measures are a combination of “basic protection” (a modified damp-proof membrane, extended to form a radon-proof barrier) with provision for additional “full protection” measures to be simply implemented (specifically, a ventilated sub-floor void or a radon sump with provision for an electrically-operated fan to be installed).

A recently published report on the effectiveness of radon protection measures concludes that compliance with the basic requirements alone has been effective in significantly reducing radon concentrations in new homes built since 1993 [1]. The report states that the percentage of homes with radon protection that are above the Action Level of 200 becquerels per cubic metre (Bq pcm) is 11.8% compared with 31.6% in all properties built without protection in comparable areas.

In homes with high radon concentrations, remedial measures that include fan-assisted diversion or dilution of radon gas before it enters a property are the most effective. However, where radon concentrations are lower, less-expensive, passive remedial measures may be sufficient to reduce in-house concentrations below the Action Level, and in some cases below the more stringent Target Level [5]. This is a conclusion of a separate CRCE report on passive remediation that suggests that passive systems (such as under-floor ventilation or sumps) should be considered when un-remediated radon concentrations are around 300 Bq pcm [2].

References/notes

1. Hodgson SA, Fonseca H, Rees DM and McColl NP (2019). Performance of basic radon protection in new homes. PHE-CRCE-046.
2. Hodgson SA and Pudner V (2019). Passive remediation for radon in UK homes. PHE-CRCE-045.
3. Radon Affected Areas are parts of the UK with a 1% or more probability of current or future homes being above the Action Level.
4. The Action Level is the reference activity concentration of radon in UK homes. Its value, expressed as the annual average radon concentration, is 200 Bq pcm.
5. The Target Level has a value of 100 Bq pcm. It is an alternative Action Level where the occupants are current or ex-tobacco smokers. In addition, remedial work should aim to reduce the radon levels to below the Target Level.

Infection reports in this issue

This issue of HPR includes:

• Suspected and laboratory-confirmed reported norovirus outbreaks in hospitals (England) and norovirus laboratory reports (England and Wales): weeks 14 to 17, 2019.