News: Radon Underground – Recent Changes


Bob Mehew has provided the following information with regard to the reduction in acceptable levels of exposure to radon gas, which might impact cave instructors and show cave owners.

The impact of working in an atmosphere containing radon above certain levels was explicitly brought within the law in 1985 and revised with the issue of the 1999 Ionising Radiation Regulations.

The 1999 Regulation 3(1)(b) stated that “any work (other than a practice) carried out in an atmosphere containing radon 222 gas at a concentration in air, averaged over any 24 hour period, exceeding 400 Bq m-3…” was covered by the regulations. Following recommendations made by the international authority on radiation, a new set of regulations was issued in 2017. The above wording was replaced by “any work (other than a practice) carried on in an atmosphere containing radon 222 gas at an annual average activity concentration in air exceeding 300 Bq m-3”.

The consultation document on the proposed changes stated that “IRR expresses the radon reference level over a 24 hour period, while the BSSD expressed the reference level on an annual basis. Calculations show the current IRR requirement is equivalent to the annual average in BSSD”. (‘IRR’ is the 1999 regulations and BSSD is the European Directive on which the 2017 regulations are based.)

What I did not identify last year was that the new 2017 regulations also created a requirement to inform the Health and Safety Executive by 5 February 2018, if you’ve previously notified HSE of (such) work, see here.

The international authority on radiation has also just made recommendations on changes to the dose impact by radon, see summary document here. That states “For buildings and underground mines, in most circumstances the recommended dose coefficient is … approximately 10 mSv per WLM” and “For the specific situations of indoor work involving substantial physical activity, and exposures in tourist caves, the recommended dose coefficient is … approximately 20 mSv per WLM”. Previous UK advice suggested a figure of around 5 mSv per WLM. The response of the European and UK authorities is awaited.

I am unable to offer advice on the topic and the above information is offered on the basis that I hereby disclaim any responsibility for any inaccuracies, errors or omissions which it might contain.

Correspondent: Bob Mehew