radioactivity

The problem of radon emission in buildings first came to light at the end of the 1970s, when a report by the Swedish National Institute of Radiation Protection revealed high radon daughter concentrations in some houses. Temporary limits on permitted concentrations in different types of dwellings were imposed in Sweden. They were related to the age of dwellings, due to the known historical use of alum shale in lightweight concrete.

Notes that the Department of the Environment is considering the implications of imposing limits for the maximum annual dose of radiation to which occupants of existing and new homes should be exposed, as recommended by the Royal Commission on Environmental Pollution in its report of 1984. Describes radon's properties and origins in buildings, where levels are at least ten times higher than outdoors. The occupants of some homes, chiefly on granitic soils, receive up to 100 times the national average dose from radon. Explains the units used when discussing radon.

Describes the different types of monitoring and sampling techniques that can determine the radiation burden of the general public from radon and its decay products. This is accomplished by measuring the range and distribution of radon and rad

Describes the aims, methods and results of a preliminary study into radon in Swiss house carried out 1981/82. In the winter of 1981/82 three Karlsruhe type passive radon dosimeters were exposed in each of 123 dwellings in selected regions of Switzerland and the results evaluated in summer 1982. Thedosimeters were normally placed in the cellar, living room and a bedroom. Gives figures for the average radon concentrations in the rooms. Notes marked regional differences caused by different geological formations.

Sources of radon and the high levels of radon in many locations and building materials in Sweden are considered. Improvements in energy conservation through the reduction of ventilation rate have lead to very high levels of radon over 1000 BqRnD/m3 in some houses. Recommendations on acceptable levels of gamma radiation on building sites and radon concentration in dwellings are given. It is estimated that there are 30-40,000 dwellings over the Swedish recommended limit of 400 BqRnD/m3 requiring modification.

Reports measurements of concentrations of thorium, potassium, uranium radium, and relative radioactivity of building materials used in the United Kingdom. Gives table of results. Examines in particular calcined gypsum prepared as a by product in the manufacture of superphosphate fertilizers. Discusses the relationship between radium concentration and gamma-ray dose rate

Reports results of measurements of the environmental radiation inside Norwegian houses. Three types of measuring equipment were used: a scintillation rate meter specially designed for low intensity measurement, a geiger counter with a rate meter, and an ionisation chamber. The average doserate in air due to environmental radiation was found to be 87 mrad/year insidehouses with outer walls of wood. 115 mrad/year for buildings with outer walls of concrete and 129 mrad/year for buildings with outer walls of brick.

Reviews literature on radioactivity in construction material. Finds that radioactivity in building materials used in the United States has received very little attention and that except for studies to find construction materials of very low background, there are no reports of radiological surveys of any U.S. building materials used for general construction purposes. Discusses surveys made outside the U.S.A. and summarized the gamma exposure rates found inside buildings (table 2). Gives bibliography of approximately 270 references.