Handbook of Radon.
27. Radon in schools: a major health risk to children?
In both the USA and the UK, much work has been undertaken to reduce radon levels in schools. Emotions have sometimes run high. In a widely distributed broadsheet describing remedial works undertaken in Cornish schools NRPB have claimed that "exposure to radon at school would have been a major source of risk to these children."
In the UK, only a few school buildings have been found over 1500 Bq/m3. The distribution may be expected to follow roughly the well established pattern for housing in the same counties. In analysing the risks to children therefore, a reasonable starting point is a high-level school, at 1500 Bq/m3.
Children attend a given school for typically 7 years, but the exact figure is not too important. During this time they may be indoors at school for around 7000 hours, which is conveniently 80% of a single year (there are 8760 hours in a year). Thus, exposure to radon indoors at school over a period of 7 years is about equal to the exposure that would be accumulated during a single year by a person living at home at the same average radon level. It is helpful here to recall that for homes the relationship between average activity concentration in Bq/m3 and dose in mSv is based on about 80% occupancy (see Section 6).
Exposure at school may therefore be set in perspective: in the worst schools it will give an integrated concentration no higher than 1500 Bq/m3.y which is, coincidentally, the 'acceptable' integrated extra concentration mentioned in NRPB's guidance on time-scales for remediation in houses. Therefore, the dose should not be described as "a major source of risk to these children". Indeed, the extra dose is lower than would be experienced by the same people during their adult lives if these were to be lived in typical Cornish houses, where radon levels may be expected in the range 50 to 200 Bq/m3, below the so-called action level.
Also, radon has been claimed to be more dangerous to children than to adults, a claim that is almost wholly devoid of any evidence. In the USA, the EPA have been condemned by scientists for trying to use radon risks to children as a 'scare tactic'. A revised view was published in their 1992 Citizens Guide.
Doses in Cornwall over a lifetime are shown in the Table below. The total of 505 mSv may be compared with the Cornish average of about 10 mSv per year, which over the first 65 years of a lifetime, yields 650 mSv.
KEY FACTS:
Claims that radon levels in schools in the affected counties represent a major risk to children are not supported by rational analysis. Despite this, radon remedial work in schools is 'good value' because of the collective dose that can be avoided: a roundabout way of saying that heavily occupied buildings are more worthwhile to treat on public health grounds than are those occupied by only a few people.
Example of
possible doses over a lifetime for a person who attended a school at
1500 Bq/m+ for 7 years, but who lived in typical Cornish houses for 60 years.
| Seven years in one of the highest level schools | 75 mSv |
| Ten years in a house at 200 Bq/m3 | 100 mSv |
| The remaining 60 years of life at 110 Bq/m3 | 330 mSv |
| Total | 505 mSv |
Based on 0.01 deaths per Sievert, the accumulated lifetime risk is only 0.5%.