INDOOR RADON GAS - A POTENTIAL HEALTH-HAZARD RESULTING FROM IMPLEMENTING ENERGY-EFFICIENCY MEASURES

Most members of the general public tend to regard their homes and the buildings in which they work as relatively safe havens from the physic al and chemical stresses of the ambient environment. However, during r ecent decades a hazardous phenomenon concerning the built environment has become apparent. it can have a detrimental effect on occupants' he alth and has implications for energy usage. Radon gas is the culprit! It has no taste, smelt or colour and its presence is therefore neither immediately apparent or readily detectable. Uranium and thorium, whic h occur naturally in rocks (e.g. granite) and soils, decay to form, am ong other elements, radon gas. This radioactive gas rises from the gro und, enters the atmosphere and is then dispersed largely in the air so giving rise to low outdoor activity-concentrations, which are, at pre sent, regarded as of little consequence for human health. However, rad on gas can enter buildings, through cracks, gaps and joints in the gro und floor, as well as from some of the building materials employed, su ch as granite. As a result, on numerous occasions relatively high indo or activity-concentrations ensue in some regions of the UK, notably Co rnwall and Devon. All buildings, including dwellings, offices, schools and workplaces have been found to have radon gas accumulating in thei r interior environments and arising mainly from below ground level. An activity-concentration in excess of 200 Bq m(-3) of air of radon is n ow acknowledged to be a health hazard to occupants within the affected building. Indoor radon gas has been cited as the second most frequent cause of lung cancel - tobacco smoke being the most virulent - with a pproximately 2500 premature deaths per annum in the UK being attributa ble to the ionising radiations transpiring from naturally-occurring ra don. Indoor radon gas currently accounts for approximately half of the average UK population's exposure to ionising radiation, which is know n to be responsible for carcinogenesis. The indoor radon problem has b een exacerbated over recent decades clue to the implementation of cert ain energy-thrift measures, which have led to relatively airtight buil dings and reduced ventilation air-exchange rates. Replacement of the a ir within buildings effectively reduces the concentrations of radon ga s that would other wise occur. Energy-thrift measures therefore can re present a health hazard for those occupying buildings which are prone to high indoor-radon activity-concentrations. However, research has sh own that remedial actions to reduce indoor-radon concentrations can be effective economically and from an energy-efficiency viewpoint. The G overnment has reacted by implementing a comprehensive radon survey of UK homes. As a result, some regions of the UK have been designated as radon-affected a eas', where compulsorily-implemented precautions shou ld be taken to ensure high indoor radon activity-concentrations will n ot occur in new homes. non-mandatory guidelines have also been issued with respect to existing buildings. However, despite the Government's extensive publicity campaign and surveys, relatively few of the existi ng homes identified as having indoor-radon activity-concentrations exc eeding the action level of 200 Bq m(-3) of air (i.e. equivalent to an annual dose of 10 mSv/year) have had remedial work carried out to redu ce the presence of radon indoors. This disappointing response is due l argely to (i) the Government's view that remedial actions ave the resp onsibility of the householder and (ii) the public's apathy towards the problem. The Government, quite reasonably, sees its pertinent obligat ion as making the public aware of the problem and giving advice about remedial actions. Nevertheless this present investigation recommends a reallocation of resources to facilitate overcoming this problem and a change in the Government's approach, so Enabling move householders to carry out remedial actions quickly. Countries world-wide are affected adversely to some extent by indoor radon gas, the problem receiving p articular attention in Sweden, Canada, Germany and the USA. However, t he present survey considers the indoor-radon problem from a UK perspec tive. (C) 1997 Elsevier Science Ltd.