The isotopes of 222Rn all emit α-particles as they decay.
Like other ionising radiation, α-particles can damage biological molecules, increasing the likelihood of cancers, genetic defects and accelerated ageing, even at low doses.
It is the Radon daughters that deliver the highest radiation dose, but Rn gas concentrations (often referred to as ‘levels’) are the ones normally measured in a room.
Average indoor readings are about 20Bqm-3 (1Bq = 1 decay per second), while the action level for homes (the concentration level above which the National Radiological Protection Board, NRPB, recommends to keep radon out of houses) is 200Bqm-3.
In 1992 Chemistry in Britain published an article on the health implications of elevated levels of radon in domestic dwellings.
At the time Rn had just become an emotive public issue in certain regions of England that had been shown to have relatively high levels of the gas.
Also in 1992 the US Environmental Protection Agency (EPA) estimated that the number of deaths from Rn in the US would be between 7,000 and 30,000.
Compared with around 23,000 fatalities from drink driving, 4,400 from fires and 1,000 from aeroplane crashes.
Such a figure was certainly a cause for concern.
By 1993 a list had been compiled of the highest concentrations of Rn in the UK. Areas where 1 percent or more of the houses exceed the action level of 200Bqm-3 where classified as ‘affected areas’.
This list included Cornwall, Devon and some regions of Scotland and Northern Ireland.
In 1996 the NRPB had measured radon levels in 250,000 home in England, advising that parts of Avon, Dorset, Lincolnshire, Oxfordshire and Shropshire should adopt affected area status. Of the 100,000 homes most at risk, 20,000 were found in areas not known to be affected in 1992.
If you think that you may be at risk from Rn in your home please contact the NRPB as soon as possible.
