radon

Radon, an inert radioactive gas, and its products of decomposition, will attack the lungs when present in high enough concentrations. Notes high concentrations of radon in mines and other underground spaces and even in well water. Radioactivity of building materials is a problem in Sweden. States concentration of radon in air is highly dependent on ventilation. Radioactivity in a dwelling is highest in the morning and drops in the daytime when doors and windows are open. Normally an air change rate of 0.5 per hour keeps radon content of indoor air at an acceptable level.

By-product gypsum, produced as a waste in the phosphate industry, could be used in bulk as a building material but it has a higher radium content than other building material. Reports an analysis of the dose rate that would result if gypsum were used for a two-storey, three-bedroom, centre terrace house. Discusses the dose from beta radiation, gamma radiation and radon gas,assuming one air change per hour.

Discusses indoor air quality in residences with low ventilation rates. Reports investigation of indoor air pollutant levels in a test kitchen with a gas stove under various air change rates. Results indicate that gas stoves generate high emissions of carbon monoxide, nitric oxide, nitrogen dioxide, formaldehyde and respirable aerosols. Recommends a kitchen ventilation rate of at least 170 cu.m.&h.< Also reports study of CO and NO2 emissions from gas appliances in an energy- efficient research house.

Reports methods used to measure the concentrations of Rn, Tn, and their decay products indoors and outdoors. Radon and Thoron concentrations are detected continuously by collecting the positively charged RaA and ThA atoms on a surface-barrier detector using electric field precipitation.< The concentrations of Radon and Thoron decay products were determined by collecting them on a membrane filter and simultaneously counting the activities by means of a collimated surface-barrier detector.Indoor and outdoor concentrations are measured simultaneously under different ventilation rates.

Reports tests of a scintillation counter to detect Ra 222 in air and water. The counter consists of a spherical cavity coated with ZnS(Ag) powder, built in a lucite cylinder whose external surfaces, excepting the window which is put in contact with a photomultiplier, are made reflective with a special paint. The performance of the detector has been analysed with respect to size,efficiency, background, constant activity and constant concentration in the sample. Finds that for liquid samples, two different values for the diameter, 5 cm. and 7.5 cm.

Reports study of the emanating power of radon from building materials. Samples of material were placed in an air-tight glass container and the radon diffusing from the sample was measured in an electrostatically operated cylindrical steel chamber in which alpha particle scintillations were counted.< Gives main results for different building materials in the form of anemanation coefficient, defined as the ratio of migrating 222Rn to the 226Ra content in the sample. Materials tested were fly-ash, slag, by-product gypsum, red brick, silicon brick, portland cement, and soil.

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.