radon

Reports measurements of Radon-222 concentrations, carried out in the living rooms of 81 dwellings in Great Britain in 1976. Measurements of the activity concentration of RaA both within the room, and of the ventilation rate for the room were made. From this an estimate of the "radon output" of the room was calculated. Gives histogram of the radon outputs in picocuries of radon 222 per litre of room air per hour. Disregarding a very high measurement in a granite dwelling, the mean was 0.54 pCi/l/h.

Reports investigation of the radon concentrations in Swedish homes. The concentrations of radon and daughter products, air change rate and gamma levels have been investigated in 63 dwellings in seven types of houses built at the beginning of the 1970's in the town of Gavle. Gives table of results. From these results the absorbed dose in the basal cells of bronchial epitheiuim in the lung has been calculated for various periods.

The authors have developed a Fortran IV computer program for estimating whole body and lung dose equivalent rates due to naturally occurring radionuclides in building materials. Two of the inputs to this program are the effects of wall thickness and the effects of a surface sealant on the gamma exposure ratedue to the increased quantity of radon daughter nuclides trapped within a wall.

Reports study of the exhalation of radon from building materials by following the build-up of activity in closed vessels containing samples of the material. On the basis of a linear diffusion model, the porosity, diffusion length and radon production rate were found for a light-weight concrete by measuring theexhalation at various, constant pressures. The exhalation of radon from wallswas measured in a concrete-walled basement room by studying the growth of activity in exhalation cans sealed to various portions of the walls.

Ventilation measurements in new Swedish houses show that they seldom fulfill minimum requirements of 0.5 air changes per. hour applicable to specific housing classifications. Basic natural ventilation is often used. Discusses consequent problems including condensation and humidity, excess radon daughters and formaldehyde content in the room air. Notes future demands for systems to include heat exchangers.

The daughter products of radon are chemically active materials which, when inhaled are very likely to deposit in the respiratory tract. Defines a special unit, the working level, to indicate the radiation burden from radon daughters. Reports study of exhalation rates from various building materials made by enclosing samples in containers and analysing air samples from the containers. Gives table of results. Discusses control of airborne radiation by increasing the ventilation rate, sealing room surfaces, mechanical circulation and filtration of the air.

Data has been obtained on the radon concentration in natural gas supplied to several metropolitan areas in the United States. The average value of 20pCi/l was selected to estimate the contribution of this source of natural radioactivity to doses from radon daughters received by individuals in homes. Radon daughter concentrations in the home atmosphere were calculated by use of computer programs for an 800 cu.ft. house in which 27 cu.ft. of gas per day was used for cooking in an unvented kitchen range.

Gives details of a method for determining the amount of radon emanating from a carbonate rock specimen. Analysis was first made with rock in solid form. An essay was then made with the material containing radium in a clear acid solution.< Discusses the need for the analysis of building material causing any type of abnormally high background variation. Outlines laws covering the buildup and decay of radon.

Describes sources of radon in materials and measures of exposure. Reviews measurements of radon in mines and dwellings. Describes measurements of the concentration of radon in a sealed chamber. Concludes that concentration of radon daughters can be reduced by removing dust from the air using an electrostatic precipitator or by using a very high ventilation rate combined with an efficient heat exchanger. Finds most significant sources of radon in dwellings are cracks and openings in the floor. Suggests reducing radon by covering bare surfaces and sealing the floor, or using a crawl space.

Reports a series of experiments made in the U.S. Bureau of Mines radon test chamber to study the effects of condensation nuclei, humidity and turbulence on the rapid deposition or plateout of radon daughter activity on the chamber walls. Under low humidity conditions the presence of a small fan reduced the working level by 41%. The activity was not deposited on the walls by the turbulent flow from the fan but actually became attached to the fan blades. High relative humidity (>80%) totally inhibited this observed effect.