Recent work by the National Radiological Protection Board indicates that higher than average levels of exposure due to radon occur in the South West. West Devon District Council has undertaken its own survey on radon concentrations to see whether these can be associated with lung cancer incidence. The control of radon gas is likely to have implications for building structure and ventilation. There is a potential conflict between the desirability of increasing ventilation to cut radon levels on the one hand and reducing air infiltration to save energy on the other.
Indoor radon concentrations are approximately lognormally distributed, with the range of concentrations varying from a one in one thousand risk of contracting lung cancer to high one per cent risk. Source strength rather than ventilation rate seems to be the major factor causing the broad distribution in concentrations. There is general agreement that the most important mechanism for radon entry into homes is not diffusion but pressure driven flow of soil gas that carries radon from the soil into the homes.
Measurements of the radioactive subsoil inside a closed and air conditioned room were made to establish how far the concentration of radon and the radon daughters may be changed by means of ventilation. Whereas the radioactive subsoil in a building cannot be influenced due to the given cosmic radiation and the radio-active isotopes, it is generally assumed that the radio-activity originated by Radon 222 may be removed from the room air by ventilators. The radon diffusing from the brickwork disintegrates into several intermediate radio-active products and finally into stable lead.
Radon-222 and 222Rn progeny concentrations, barometric pressure and pressure differentials between inside and outside were measured continuously in the basement of a recently constructed energy-efficient house in metropolitan Denver, Colorado
The effect of small aerosol particles and the effect of air cleaning devices on the behaviour of the decay products of radon have been studied. The long term measurements in a one-family house have shown that the behaviour of the decay produc
This paper reviews the literature on sources and measurement of natural airborne radionuclides and radiation in buildings. It also briefly reviews control measures and suggests areas for further research. The major emphasis is given to radon 222 and its daughters, since they typically cause thelargest organ dose to the general population, most of which arises from indoor exposures. The indoor radiation field from radionuclides fixed in building materials and soil is also given substantial treatment.
In the past several years measurements of radon and its daughters made in residential buildings in the USA indicate that in some situations the potential health hazard to the occupants of buildings from inhalation exposure can be significant.
The effects of retrofitting for building tightness, air-to-air heat exchangers, and HVAC circulation fans on radon and radon progeny levels were investigated using two matched test houses.
There are three general categories of techniques for the control of radon and radon progeny concentrations in indoor air - restriction of radon entry, reduction of indoor radon concentrations by ventilation or air cleaning, and removal of airborne radon progeny.
Reports on project designed to illustrate building and ventilation solutions which are or which can be expected to reduce the radon daughter content in indoor air in existing buildings or to prevent excessive radon daughter contents in newly-
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