Handbook of Radon.
25. Preventable radon deaths in the UK.
Amongst the few numbers that the Press have used relating to radon are NRPB's estimates of UK lung cancer deaths in which radon might be implicated. A few years ago the 'best guess' was 1500 per year, but revisions of risk factors (rather than modified estimates of the average level of radon in houses) suggested 2500. Use of this figure enhanced both interest and concern in the affected counties.
More recently, research has suggested that radon in homes may be less dangerous compared to radon in mines as had been supposed. A figure of 1600 deaths is used in the Government's recent White Paper "The Health of the Nation", but this applies only to England. However, eminent scientists concede that radon risk factors for houses may still be uncertain by a factor of five, and EPA in the USA has markedly lowered its projections for non smoking radon deaths.
Most estimates are derived by assuming that the more radon you breathe the more likely it is to kill you. They are based on the so-called linear dose-response model, and on many uncertainties.
However, even assuming that all the calculations are broadly correct, it is deliberately misleading to present the risks from radon utilising a single calculated statistic.
There are two reasons for this. Firstly, the consensus of scientific opinion is that a given dose from radon is possibly 10 or 15 times as dangerous to a smoker as to a non-smoker. Thus, three quarters or more of so-called radon deaths may be linked with smoking. Only a quarter may be in non-smokers. In the 1990 second edition of the DOE Householders' Guide to Radon this point is presented clearly. Likewise, the subject is properly presented in the 1992 edition of EPA's Citizens Guide.
Secondly, most radon deaths are calculated to occur not in Devon and Cornwall, but from the small radon exposures to tens of millions of people living in tens of millions of ordinary houses elsewhere in the UK. Thus, addressing the radon problem in Devon and Cornwall cannot influence 1500 or 2500 premature deaths per year, but perhaps less than 100. Of these, less than 25 may be non-smokers.
Studies are being undertaken in several countries to determine to what extent domestic radon really poses a threat to homeowners. An apparent contradiction is that rates of lung cancer in the 'high radon' counties of Devon & Cornwall are lower than in other regions of the UK. It is thought this arises from a slightly lower incidence of smoking and the later commencement of smoking in rural districts.
In assessing the risk of lung cancer from radon exposure, smoking is called a confounding factor - because it obscures what might otherwise be a clear correlation between regions of higher than average radon and regions having a higher than average incidence of lung cancer. However, beware of simple correlations, see Section 30.
KEY FACTS.
Most radon exposure occurs in a large number of 'ordinary-level' houses. Only about 4% of total UK exposure occurs in 'high-level' houses.
Realistically, around 10 premature non-smoking deaths might be avoided in the UK annually as a consequence of undertaking successful radon remedial action in tens of thousands of houses. Remedy of the 2000 highest level houses (those above 1000 Bq/m3) might prolong the lives of 2 or 3 non-smokers per year.
In contrast, smoking has been quoted as causing around 100,000 premature deaths per year in the UK, to which may be added around 5000 owing to accidents in the home. In one year 25,000 or more people may die of influenza in the UK, and 2000 from asthma. Many of these may be preventable premature deaths.
In the USA it has been estimated that a multi-billion dollar radon remediation campaign would have the same effect on premature death as a 1% reduction in smoking.