Activated carbon canisters were tested to determine their adsorption and retention characteristics for radon. Our tests conducted indoors under typical conditions of temperature and relative humidity indicate that simple, inexpensive and maintenance-free passive devices containing 150-200 g of activated carbon can measure radon conveniently and adequately. The amount of radon absorbed in the collector is determined by counting the gamma rays from the decay products of radon. The lower limit of detection for radon is 0.2 pCi/l. for an exposure of 72 hr. Greater sensitivity can be obtained with larger counting systems and devices containing carbon with more surface area. Tests in a residential building and in a test chamber indicate that the measured radon in the canister is proportional to the mean concentration of radon during the period of exposure when correction for relative humidity is made. For practical situations encountered indoors, the device yields results accurate to within +/- 20%. Results from field measurements indicate that the use of the device is feasible.
Radon and radon progeny measurements are conducted world-wide for the assessment of the radiation dose to workers and the general public. In the last 10 years, a variety of instruments have been developed that utilize different principles of detection for different measurement applications. The various instruments and methods used today depend on whether radon or radon/thoron progeny are being measured, the type of radiation being detected, and also the duration of the measurement. Other important design criteria are applicability, portability, convenience, reliability, and cost considerations. The instruments under consideration use the following detection systems: pulse ionization chambers, electret ionization chambers, scintillation detectors with zinc sulfide ZnS(Ag), alpha particle spectrometers with silicon diodes, surface barrier or diffused junction detectors, registration of nuclear tracks in solid-state materials, and gamma-ray spectometry with NaI(TI) scintillation crystals or germanium lithium (GeLi) semiconductors. Discussed in this paper are the advantages and disadvantages of the various portable instrumentation used for measuring radon, thoron, and their progeny. Also provided is guidance for their application in the field.
The US radon measurement programme began in the late 1950s by the US Public Health Service in Colorado, New Mexico and Utah during the uranium frenzy. After the 1967 Congressional Hearings on the working conditions in uranium mines, the US Atomic Energy Commission (AEC) was asked to conduct studies in active uranium mines to assess the exposure of the miners on the Colorado Plateau and in New Mexico. From 1967 to 1972, the Health and Safety Laboratory of the US AEC in New York investigated more than 20 uranium mines for radon and radon decay product concentrations and particle size in 4 large uranium mines in New Mexico. In 1970, the US Environmental Protection Agency (EPA) was established and took over some of the AEC radon measurement activities. Between 1975 and 1978, the Environmental Measurements Laboratory of the US Department of Energy conducted the first detailed indoor radon survey in the USA. Later in 1984, the very high concentrations of radon found in Pennsylvania homes set the wheels in motion and gave birth to the US Radon Industry. The US EPA expanded its involvement in radon issues and assumed an active role by establishing the National Radon Proficiency Program to evaluate the effectiveness of radon measurement and mitigation methods. In 1998, due to limited resources EPA privatised the radon programme. This paper presents a personal perspective of past events and current status of the US radon programme. It will present an update on radon health effects, the incidence rate of lung cancer in the USA and the number of radon measurements made from 1988 to 2013 using short-term test methods. More than 23 million measurements were made in the last 25 y and as a result more than 1.24 million homes were mitigated successfully. It is estimated that <2 % of the radon measurements performed in the USA are made using long-term testing devices. The number of homes above the US action level of 148 Bq m(-3) (4 pCi l(-1)) may be ∼8.5 million because ∼50 million homes were added since 1990 to the home inventory. This paper will discuss the current instruments and methods used to measure radon in the USA, and what is the effectiveness of radon resistant new construction, the current status of mitigation standards and the proposed testing protocols in schools and large buildings.
Abstract:In 1900, Dorn discovered the emanation in the uranium series that eventually became the well-known gas 222
Uranium mine and laboratory experiments are described for the determination of total respiratory deposition of radon daughters together with the effect of particle size, tidal volume, respiratory frequency, nasal deposition and growth of radon daughter particle size. Total respiratory deposition of radon daughters measured in humans exposed in uranium mines was found to range from 23% to 45%. From the mine and laboratory experiments, both particle size and tidal volume were found to influence deposition, fractional deposition increasing with decreasing particle size and increasing tidal volume. Particle size differed with location within a mine. No dependence of deposition on respiratory frequency or minute volume was discerned.In laboratory experiments, nasal deposition of attached and unattached radon daughters was found to be 2% and 62%, respectively, and evidence was developed indicating the rapid growth of radon daughter particles in the respiratory tract.
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