The reliability of radon reduction techniques.

It is estimated that more than 5000 householders in the UK have taken steps to reduce high radon levels in their homes. In 1993 a number of homes with successful remedies installed were asked to participate in a study to determine the long term reliability of those systems. This involved the annual remeasurement of the radon concentration in each dwelling. Results for 26 of the dwellings which have 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 mechanical failures in active systems. Significant variations in reliability have been seen in natural ventilation of the 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 of these were noticed and corrected by the householder. There was a rate of 0.6% per annum for failures that went unnoticed.