radon

Discusses sources of radon in buildings and the prediction of levels of radon and daughters. Derives differential equations governing the decay and venting of radon and its daughters. A computer program based on these equations has been written to predict radon and daughter concentrations, total potential alpha energy concentration and equilibrium factor. The program can account for time dependence of ventilation and emanation rates and is readily used by building designers.

Notes one of the principal ways in which members of the public receive natural irradiation is by breathing the decay products of radon 222. Reviews data on radiation exposure and the incidence of cancer for uranium miners. Discusses uncertainties and inadequacies in the data. Gives estimates for the incidence of lung cancer in the general public, caused by radon exposure.

Reviews the topic of indoor air quality as it relates to energy efficient homes. Discusses air pollution from combustion, airborne particles, formaldehyde and radon. Concludes that indoor air quality in existing homes and those currently being constructed, can be managed so as to avoid adverse effects on the occupants.

Presents a new method for determining the airborne concentrations of RaA, RaB and RaC in atmospheres contaminated with radon-222. The method employs alpha spectroscopy to measure the count rates of RaA and RaC' present on a membrane filter sample at two post-sampling times. The individual air concentrations and the statistical variances associated with each may then be calculated from the equations given. Presents theoretical and experimental comparisons which indicate the improved accuracy of the spectroscopic method over methods previously available.

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.