Estimating the dose from radon to recreational cave users in the Mendips, UK

The concerns over the risks to human health from radon in dwellings are well documented and extensive arrangements are in place for measuring and dealing with elevated levels. Similar arrangements are in place for work-place exposure, but uncertainties exist in dealing with locations not falling into either of these categories. In caves, radon has been identified as occurring at elevated levels by a number of groups; but, with the exception of major show caves, its impact and risk to those who work in the caves has not received adequate attention thus far. This paper details a survey performed in a relatively “low-risk” geographical area of the UK and proceeds to quantify the risk of exposure in the cave environment. Radon levels of 12,500 Bq m−3 have been recorded but this is likely to underestimate the levels in many parts of the cave system for reasons associated with cave architecture and aeration. Annual doses to certain groups of cavers have been calculated to be as high as 120 mSv.