Handbook of Radon.
21. Simplified explanation of the risks from radon.
The risk from living with higher levels of radon over many years is an increased chance of lung cancer in later life. This is well established from studies of miners, although the statistics derive primarily from miners who smoked. This is simply because in the years of interest, before radon levels in mines had been addressed by using better ventilation, smoking was a prevalent habit amongst working class men.
There is less compelling evidence for the risks to non-smokers. Amongst the variables are that conditions in mines are dissimilar to those in homes. Miners are sometimes also exposed to thoron (see Section 7) and because of the long half-lives of thoron daughters, the inhibition of lung clearance that occurs in smokers may be significant. These and other factors complicate the calculation of risk factors for housing.
Links with leukaemia and other cancers may be regarded as 'not-proven'. If these and other effects do occur occasionally, the risk factors are almost certainly much less than for lung cancer - see Section 30 also.
Whilst radon and lung cancer are undoubtedly linked, some perspective can be obtained by comparing the risks with those of smoking.
It is broadly accepted (except of course by some tobacco companies) that smoking one cigarette per day gives a lifetime risk of about 1%. In other words, a person who smoked one cigarette a day all his life would have a 1% chance that he would eventually die from the habit - and a 99% chance that he would die from some other cause. Indeed, his (or her) risk of dying from some form of cancer would be around 20%, so smoking one cigarette a day for life can be thought of as increasing this average prevailing 20% risk by about 1%, to perhaps 21%. Whilst this 1% calculated risk can be avoided, so can larger risks according to some studies (see Section 31).
In contrast to these small risks, a lifetime smoker with a 50-a-day habit has a better than even chance that the addiction will eventually kill him. Of course, not all 100-a-day smokers will die from a smoking related illness - that is not how statistics work - but the risks are very high nevertheless.
The NRPB risk factor for radon at the so-called 'action level' is 1% for a lifetimes' exposure for non-smokers. Recent EPA estimates indicate lower risks, see Section 28.
Whatever the true position, there need be no great concern about a level of 200 Bq/m3 in homes. People do not panic if they discover that a member of the family is smoking one cigarette per day. Neither should they panic over low levels of radon, or be pressurised into over-hasty action to modify buildings.
The risks are probably much greater for smokers, but in both the UK and USA it is these people who most of all have proved unreceptive to publicity encouraging action for health.
KEY FACTS:
Moderate amounts of radon do not pose much of a risk to non-smokers - perhaps less than the risk of dying in a home accident or on the roads, and a lifetime exposed to radon at the action level (or approximately 10 years at 1400 Bq/m3 or 5 years at 2800 Bq/m3) is no greater cause for anxiety than is driving a car or smoking one cigarette a day for decades.
The so-called 'action level' is not a danger level and it is not a safety level. It is (merely) a useful reference point for contemplation of remedial action. In the short term at least, only houses above 2000 (two thousand) Bq/m3 warrant anxiety.
There are many differences between mine environments and room air in homes, between the risks from radon and thoron in mines and homes and between risks from radon and thoron to smokers and non-smokers. Some care in extrapolating risk factors is necessary, and studies are proceeding in several countries.