Radon is a naturally occurring gaseous element formed mainly by the radioactive decay of uranium present in rocks. It is common among homes, workplaces caves and mines. Radon levels tend to be higher within caves and mines during the Summer as the warmer air draws radon out of the rocks. Radon is measured in Becqurels (Bq) per cubic meter.
Exposure to radon must be managed should staff working underground work in an environment which exceeds a threshold of 300Bq m3 annually (previously 400Bq m3, the threshold was changed in the latest regulations, IRR17, which came into effect in February 2018).
Further details on Radon Underground is available in a document produced by and for the BCA. This document is now out of date (due to the revised changes) and is currently being reviewed. In addition the BCA is currently reviewing the guidance issued regarding radon with the view to present national guidance to all working underground.
At present the guidance from the BCA is that any provider who thinks staff may be exposed to 300Bq m3 of radon must notify HSE. This is a free and simple on-line process which can be done by the employer by following this link: https://services.hse.gov.uk/bssd/?c=1