Handbook of Radon.
41. Avoiding undue risk: time-scales for radon remediation.
This Section presents a perspective of radon risks for non-smokers. Not everyone who smokes tobacco dies of lung cancer or heart disease and not everyone who is exposed to high activities of radon will contract lung cancer. There is inevitably an element of chance, of luck. It is known that some people are genetically more predisposed to some types of cancer than others. Advice has to be given in terms of average risks. A suggested scheme is given below in terms of annual dose. However, readers MUST refer to the Bq/m3 figures to relate the advice to their radon levels, as reported by measurement companies.
Dose from radon. (mSv/year) and the corresponding average indoor radon levels in housing and schools, during occupied hours.
0 to 10 mSv
(0-200 Bq/m3 in housing or up to 1400 Bq/m3 in schools).
This is a very low radiation dose. There is no pressing need to do anything. Annual risk is about the same as the average persons risk of being killed on the roads or by an accident in the home.
10 to 20 mSv
(200-400 Bq/m3 in housing or up to 2800 Bq/m3 in schools).
This is a moderate radiation dose, about equal to what radiation workers are allowed to receive. Action could be considered in the next five to ten years. The annual risk is up to twice that of being killed on the roads, or in the home
20 to 40 mSv
(400-800 Bq/m3 in housing or up to 5600 Bq/m3 in schools).
This is more than twice the 'action level' for existing houses and the annual dose is in excess of what nuclear workers are normally allowed to receive. Remedial measures should be considered over the next few years. There is no need to be too alarmed - the risk is only equivalent to smoking a few cigarettes per day unless you are already a smoker, when the risks from radon exposure will be higher.
40 to 75 mSv
(800-1500 Bq/m3 in housing or up to 10,000 Bq/m3 in schools).
It would be unwise to live for years exposed to these doses from radon. The annual risk is up to 10 times that of being killed on the roads. Annual doses above 50 mSv are illegal if received by way of occupational exposure - during work in the nuclear or any other industry. Remedial action is advised within a year or two.
75 to 125 mSv
(1500-2500 Bq/m3 in housing or over 10,000 Bq/m3 in schools).
The radiation dose exceeds the maximum permitted level for UK nuclear workers. Remedial action should be taken within a year. There is no need to panic. The risk of lung cancer is still less than that of the average smoker.
125 to 250 mSv
(2500-5000 Bq/m3 in housing or over 15,000 Bq/m3 in schools).
These radiation doses are very significant - the risk is up to 25 times the average risk of death on the roads
250 to 375 mSv
(5000-7500 Bq/m3 in housing or over 50,000 Bq/m3 in schools).
Action is advised well within a year. Only a handful of buildings in the UK have such high levels, although several cellars are known to be affected to this extent.