The reliability of radon reduction techniques

It is estimated that more than 5000 householders in the UK have taken steps to reduce high radonlevels in their homes. In 1993 a number of homes with successful remedies installed were asked toparticipate in a study to determine the long term reliability of those systems. This involved the annualremeasurement of the radon concentration in each dwelling. Results for 26 of the dwellings whichhave data spanning 6 years, with a further 32 which have data over a shorter period, are discussed.The study shows that all reduction techniques can remain durable, though there are some mechanicalfailures in active systems. Significant variations in reliability have been seen in natural ventilation ofthe underfloor void due to the effects of environmental conditions, such as wind speed and direction.The overall failure rate for reduction techniques was found to be 4.5% per annum. However, most ofthese were noticed and corrected by the householder. There was a rate of 0.6% per annum for failuresthat went unnoticed.