Radon Concentration In Air Research Articles

A Portable Radon Meter

A portable instrument for the measurement of radon (222Rn and 220Rn) in air or in water is described. The instrument consists of an ionisation chamber and an electrometer amplifier for the measurement of the ionisation current. Concerning the radon concentration in air, the sensitivity of the instrument is adequate for radiation protection measurements. Additional applications are the measurement of radon concentrations in water and the measurement of radon in soil gases allowing uranium exploration or earthquake prediction research.

Variation in Long-Term Radon and Daughters Concentration with Position Inside a Room

Bare plastic detectors (LR-115 and CR-39) were used in similar conditions to record a particles from radon and its daughters in more than one hundred houses in the UK. It was found that LR-115 is more convenient than CR-39 because of its energy discriminating properties. Variation in the long-term radon and daughter concentration in air was observed in houses by placing bare nuclear track detectors of both types at different positions in the same room. Variation in the concentration of tracer gases at different positions in a room has also been observed through ventilation measurements using gas chromotographic techniques. The significance of these variations for exposure assessment is discussed.

Electret--a new tool for measuring concentrations of radon and thoron in air.

Electret is an electrical analogue of a permanent magnet and it carries permanent electrical charge. A negatively charged teflon electret is used for the collection of decay products of radon or thoron (positively charged) formed inside a 10-l. wire mesh chamber whose sides are covered with 25-mm thick polyurethene foam. Teflon electret provides an electric field inside the chamber equivalent to that provided by a battery of 2000–3000 V. In dry conditions, nearly 70% of all the decay products of radon and thoron formed in the chamber are collected on the surface of the electret. After a known sampling time the electret is subjected to programmed a-counting to compute concentrations of radon and thoron. With a 3-hr sampling and subsequent counting, minimum detectable limits work out to be 30 pCi/m3 for radon and 110 pCi/m3 for thoron. The method is ideally suited for measurement of levels normally encountered in the environment and in dwellings. The paper discusses the method of preparing and characterizing electrets; the dependence of the collection efficiency upon relative humidity, area of the electret and the charge on the electret. Field measurements made by this method and the standard double filter system are shown to agree well.

Radon concentration in the soil air measured by track detectors

A solid state nuclear track detector Kodak LR 115 has been used for measuring the radon concentration in the soil air in depths up to 1 m. The detection efficiency of polyenergetic alpha particles emitted from thick solid samples has been evaluated. A relation has also been found between the alpha activity of 222Rn in the air and the track density. From the track densities registered by detectors exposed to 222Rn alpha radiation and its decay products 218Po and 214Po in the air of the soils, the average diffusion coefficients of radon in the soils have been computed as well as the average radon flux densities from the soils into the atmosphere. A rough estimation of the background interval of the track detector has been made. This estimation can be used during prospection of uranium ores.

Radon and radon daughters in homes utilizing deep well water supplies, Halifax County, Nova Scotia

Abstract The concentration of radon in tap water supplies varied from 47 nCi/1 to 370 nCi/1. Indoor air concentrations varied from <0.5 pCi/1 to 19.1 pCi/1 and 0.001 WL to 0.025 WL for radon and radon daughters, respectively. The transfer of radon from tap water raised the radon concentration in the bathroom air during operation of the shower. Transfer efficiencies of 37% to 70% were observed.

Radon concentration of air over the Eastern Arabian Sea

The radon concentrations of air samples collected during the South West monsoon period at altitudes up to 4 km over the Arabian Sea at two locations,i.e., 0–50 km and 300–400 km west of Bombay, are reported. Radon was extracted from air, using a simple single stage apparatus. The concentration of radon in the monsoon air mass was found to range around 80–100 dpm/m3 STP, indicative of its recent continental origin. The results suggest that the coastal monsoon air mass, up to 400 km west of Bombay coast, is generally homogeneous and vertically well mixed.

Using natural radon for delineating monsoon circulation

The presence of a major continental component in the monsoon air mass has been detected from radon observations made over the Arabian Sea and the Indian Ocean. The concentrations of radon in equatorial maritime surface air are found to be low (2–3 dpm/m3); in the monsoon air over the west Arabian Sea they are similar, but values gradually increase (∼20 dpm/m3) as the monsoon approaches the west coast of India. This result can be interpreted in terms of mixing between the lower maritime air and the continental air above. The usefulness of vertical radon profiles in further delineating some aspects of monsoon circulation is pointed out.

An attempt to trace the Monsoon Flow using Natural Radon

Measurements of radon concentration in air over the Arabian Sea and the Indian Ocean are reported. They enable an identification of south cast trades and of continental air in the monsoon current.

Etude des noyaux de condensation radioactifs de l’atmosphère

A comparative study has been made between the Radon and Thoron decay products in the atmosphere, by means of α radiation counting, using Zeleny tubes, a diffusion battery, or paper or membrane filters for sample collection. Some of the characteristic properties of the radioactive ions are studied with mobilities above 10 −3 cm 2 sec −1 V −1 , radius below 2·10 −6 cm. Neutral radioactive condensation nuclei are measured by means of a diffusion battery. The average air concentrations of Radon and Thoron are determined. The results indicate that for the Radon daughters, as well as the Thoron daughters, about 42% of the total α activity is found on particles having a radius less than 2·10 −6 cm. A theoretical discussion of the experimental results is made. DOI: 10.1111/j.2153-3490.1966.tb00275.x

A scintillation counter for the measurement of radon concentration in air

A method is described for measuring the radon content of three litre samples of atmospheric air without pretreatment. The apparatus used consists of a 12 in. photomultiplier with ZnS(Ag) phosphor and counting chamber. A measured efficiency of 38%, when the phosphor is negatively charged, is in good agreement with theory. The ultimate sensitivity is governed by the background which is equivalent to a concentration of 5 × 10-14 cl-1.

A stable, low-background, high-efficiency scintillation counter for analysis of low levels of radon concentrated by adsorption on charcoal.

Scintillation counters for the measurement of radon have been developed by Damon and Hyde (1), Malvicini (2), and Van Dilla and Taysum (3). Marked improvement in stability was obtained at this laboratory by a modification designed to ensure a reproducible distribution of radon and its daughters within the counter. In addition, lower backgrounds were obtained by the use of steel for the counter shell and quartz for the window. The usefulness was further augmented by adsorbing the radon from gases, liquids, and solids on charcoal. The radon was then transferred to the scintillation counter with a small volume of helium. The scintillation counter has a volume of 96 c.c. and is constructed from an inexpensive Kovar seal. It is coated on the inside with silver activated zinc sulfide to a thickness of 20 mg.∕sq. cm. for optimum pulse height. A clear quartz window having a transparent conductive tin coating on its inner surface is sealed on the open end of the counter. It was found that, in the absence of the conductive tin coating, the negative voltage on the photo-multiplier tube induced a charge on the quartz window which, in turn, concentrated thereon the decay products of radon. This caused a low counting efficiency, which varied considerably in the presence of gas impurities such as water vapor. The calculated efficiency of the counter for the case of radon in the gas phase and all the daughters on the window agreed well with the experimental value of 3.97 cpm∕μμLc radon obtained with non-coated windows and dry helium. The counting efficiency obtained with aliquots of radon from two N.B.S. calibrated radium solutions was 5.42 ± .06 cpm∕μμc radon (0.82 counts per alpha) for a counter with a coated window. This corresponds to the efficiency calculated for the case of radon in the gas and the daughters uniformly distributed on the counter walls and window. The efficiency and reproducibility of ten additional counters were obtained by comparing the counting rates of aliquots of radon from a large reservoir. The counting efficiency of any two counters was found to agree within 2 per cent, and the reproducibility for any one counter was ± 1 per cent. The counting efficiency has remained constant during the six-month period it has been observed. The background counting rate of newly constructed counters is 0.08 cpm. This background is stable over long periods of time except as increased by RaDEF residues from high counting rate samples. Instrumental spurious counts contribute approximately 0.003 cpm. Thus a stable, low-background, high-efficiency radon counting system has been developed. This system is suitable for the analysis of amounts of radon as small as 10−14 c or, when charcoal adsorption is used, concentrations of radon in air as low as 10−16 c radon∕liter.