those over 1,000 Bq/m³,

those between 400 and 1,000 Bq/m³ and

those between 200 and 400 Bq/m³.

If the EC action level of 400 Bq/m³ is taken as a threshold, about 20,000 houses are 'affected' in the UK, which is about 0.1% of the stock of 22 million homes.

Using the linear dose-response model (see Section 25) it is easy to calculate how many premature deaths may occur each year as a result of exposure to radon in each of these three groups.

However, it is important also to calculate how many premature deaths might be avoided and for what expenditure. It is necessary here to be realistic, just as it is sensible to assume that not all smokers will give up smoking for the good of their health.

In the Table below, it is assumed that in the first group (houses containing more than 1000 Bq/m³ of radon) action will be taken in over 80%, and to 80% effectiveness. However, it is unlikely that over 80% of these houses will be found in the near term.

In the other groups, it must be assumed that because of the lower risks, there will be less concern and (consequently) less remedial action. Houses below 400 Bq/m³ do not pose much risk except over decades of occupancy.

In summary, the first group of houses are most urgent in terms of specific risk. The next group are less urgent, more dispersed, and therefore more difficult to find, and so on. Houses above 200 Bq/m³ are widespread in several counties.

Only by attempting to remove all radon from all buildings could most of the 2500 radon-related deaths be addressed - and this would require truly massive expenditure.

However, this has not prevented some officials from stating that all (presumed) radon deaths could be avoided were a large public programme to be sanctioned to address high level houses. Such statements have been allowed to pass unchallenged and have caused considerable confusion.

KEY FACTS:

Only about 4% of radon dose in the UK is associated with high-level buildings, and mostly with houses. Only a few premature deaths of non-smokers could be prevented by a programme to find and treat many of these houses. For smokers, their higher risks could be reduced simply by stopping smoking, although their risk of lung cancer may remain elevated for a decade or more.

In terms of cost-effectiveness of public finance, only treating the very highest level houses appears to be good value, compared with what could be achieved elsewhere within health budgets, see Section 39.

Note: some numbers are rounded. There is little point in presenting radon statistics to high precision because of uncertainties in both radon measurements and risk factors. A perspective of the world radon problem could be obtained from a summation of similar Tables, one for each country.

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