BASES AND CRITERIA FOR AIR QUALITY STANDARDS.
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Air Pollution↗
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RAINFALL AND MONSTERS.
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Abnormalities, Severe Teratoid↗
Environmental radioactivity measurements in Kastamonu region of northern Turkey.
Located in the north-western part of Turkey, the province of Kastamonu has lately been receiving national attention because of its cultural and touristic attractions. This study assesses the environmental radioactivity levels of the region through measurements of indoor radon concentrations and indoor/outdoor gamma absorbed dose in air and radionuclide activities in surface soil and drinking water. The indoor (222)Rn activity concentration was found to be 98.4 Bq/m(3) equivalent to an annual effective dose of 2.48 mSv. The indoor and outdoor gamma absorbed doses were measured as 54.81 and 48.03 nGy/h, respectively, corresponding to a total gamma radiation level (of terrestrial and cosmic origin) of 0.33 mSv/y. The activity concentrations in the soil samples collected from the study area were determined as 32.93, 27.17, 431.43 Bq/kg for the natural radionuclides (238)U, (232)Th and (40)K, respectively, and 8.02 Bq/kg for the fission product (137)Cs. These natural radioactivity sources result in a terrestrial gamma level of 60 microSv/y. The water samples collected from the region carry an average of 0.0089 Bq/l of gross alpha and 0.271 Bq/l of gross beta activities which together cause an annual effective dose of 1.83 microSv. The measurement results obtained in this study indicate that the region has a background radiation level that is within the natural limits and shows no significant departure from the other parts of the country.
Air Pollutants, Radioactive↗
[RADIOACTIVE POLLUTION. BIOLOGICAL CHANGES].
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Air Pollution↗
Assessment of the radiological impacts of a zircon sand processing plant.
The paper presents the results of a study on radiological impacts resulting from a zircon sand processing plant located in the North-Eastern part of Italy. Activity concentrations of radionuclides found in materials associated with this industrial process are presented as well as the results of the assessment of the annual effective doses to the workers and the members of the public. Gamma-spectrometric analyses were performed on "raw" sands, end-products, and soils sampled near the plant. Thermoluminescent dosimeters, electric pumps and electret ion chambers were used to measure the external irradiation, the indoor dust concentrations and the radon concentrations, respectively. The ground-level air concentration of radioactive particulate near the plant and the deposition of particulate matter were estimated by a Gaussian model (ISCLT3). Finally, the annual effective doses, calculated as provided for by Directive 96/29/Euratom, were estimated to be 1.7 mSv y(-1) for workers and 4.4 microSv y(-1) for members of the public.
Air Pollutants, Radioactive↗
Challenges in harmonising controls on the radioactivity of building materials within the European Union.
Possibilities for harmonising controls on the radioactivity of building materials within the European Union are being discussed in a Working Party on Natural Radiation Sources established by the Article 31 Group of Experts (Euratom Treaty). The Working Party is preparing a document to aid the Article 31 Expert Group and the European Commission in considering possible recommendations and technical guidance to the Member States for the implementation of the new Basic Safety Standards Directive concerning the radioactivity of building materials. The discussions in the working party have demonstrated several challenges in the possible harmonisation of controls, many of them arising from some significant differences in national circumstances.
Air Pollutants, Radioactive↗
Natural radiation exposure in the vicinity of Spanish nuclear power stations.
Nationwide and regional surveys have been conducted to evaluate natural radiation exposure of people in the vicinity of the Spanish nuclear power stations. In these surveys, indoor radon, external gamma dose rates outdoors and indoors and radioactivity in soils were measured. Measurements of indoor radon concentrations were performed in 214 dwellings by using nuclear track-etched detectors. External exposure from terrestrial gamma rays outdoors and indoors were measured in a total of 596 points. Radioactivity in soil samples collected at 293 sampling sites are also reported in this paper. By taking into account all sources of natural radiation exposure, mean annual effective doses to the population in the surroundings of the six Spanish nuclear power stations have been estimated and compared with those coming from their normal operation.
Air Pollutants, Radioactive↗
A very low-background gamma-ray counting facility in the Baradello underground laboratory.
An underground station for the measurement of low-level radioactivity is in operation in Northern Italy in the town of Como under the Baradello hill. The rock cover is -300 m water equivalent. This paper reports about the preliminary measurements carried out to characterise the site of the Baradello hill and the installation of a high-purity Ge detector with a radio-pure copper shielding. Features and levels of the achieved background are reported and discussed, in comparison with other above ground and underground low-radioactivity stations. Sensitivities to radioactivity in typical environmental matrices are evaluated, confirming the very low-gamma background attained in the laboratory.
Air Pollutants, Radioactive↗
Occupational exposure of phosphate mine workers: airborne radioactivity measurements and dose assessment.
Under the Egyptian program for radiation safety and control, airborne radioactivity measurements and radiological dose assessment were conducted in some phosphate and uranium mines. Abu-Tartor mine is one of the biggest underground phosphate mines in Egypt. Airborne radioactivity, radon ((222)Rn) and its short-lived decay products (progenies) and thoron ((220)Rn), were measured in selected locations along the mine. The environmental gamma and workers dose equivalent rate (mSv/y) were measured inside and outside the mine using thermo-luminescence dosimeters (TLD). The results were presented and discussed. The calculated annual effective dose due to airborne radioactivity is the main source of occupational exposure and exceeding the maximum recommended level by ICRP-60 inside the mine tunnels. A number of recommendations are suggested to control the occupational exposures.
Air Pollutants, Radioactive↗
Radiological impacts of the amang processing industry on neighbouring residents.
The processing of amang (one of a number of tin-tailing products) for its valuable minerals has associated with the radiological and environmental problems. The processing and stockpiling of amang and ilmenite in open-air spaces, subject as it is to environmental influences, gives rise to a potential for affecting residents in adjacent area. A case study was carried out in a residential area neighbouring a typical amang plant to investigate the radiological impact to the residents. The average Effective Dose rates, calculated based on the contributions of Effective Dose rates from inhaled suspended radioactive dust, radon-thoron and their progeny, and external gamma radiation, were determined for selected houses. Results show that the occupants of those houses received Effective Dose rate, which cannot be differentiated from background. The major contributor to the average Effective Dose rate came from external radiation sources. Inhaled radon and its progeny was the second major contributor.
Air Pollutants, Radioactive↗
Limits and uncertainties--with special regard to radon measurements.
The concept of limits was introduced to assure a commonly tolerated low health risk from the exposure to radioactivity or chemicals. In most countries concentration limits are given by the authorities and are fixed to certain values. The question is how to prove compliance with limits, keeping in mind that all measurements are subject to uncertainties. This means there is always a certain probability for a wrong decision. Generally, the authorities demand only the answer "below" or "above" the limit and will not accept statements on probability. Advantages and disadvantages of different decision making philosophies are discussed.
Air Pollutants, Radioactive↗
[Radon levels in interiors in Valtellina, on the Angera hills and in the high valley of the Cervo river].
The results are reported of an investigation carried out from 1988 to 1990 in many houses in various sites in Lombardy and Piedmont. Measurements were actually carried out in Valtellina, in Angera--on the Lombard side of lake Maggiore--and in the high valley of the river Cervo, north of Biella. The patterns of radon immission in houses due to buildings materials and also to soil emissions are described. Average values of radon levels were obtained using track-etch detectors, whereas fluctuations were recorded daily with a unit capable of detecting alpha particles in real time. Some of the values obtained in 28 Valtellina towns were quite high--e.g., about 1,000 Bq/m3 in towns along the Insubrica fault. The area around Bormio and the Masino valley did not exhibit high radioactivity levels. A total number of nearly 100 houses were investigated in Angera; the highest radon concentrations were observed in cellars and especially in the areas where fractures are bigger and more diffuse. One particular house was accurately examined with real-time analysis of radon fluctuations. Four small towns in the pluton area were investigated in the valley of the river Cervo. In this instance, values were generally high (mean concentration: 842 Bq/m3); the highest concentrations were found in cellars and in ground-floor rooms.
Air Pollutants, Radioactive↗
National survey on the natural radioactivity and 222Rn exhalation rate of building materials in The Netherlands.
The present study reports on results of a nation-wide survey on the natural radioactivity concentrations and Rn exhalation rates of the prevailing building materials in the Netherlands. In total 100 samples were taken and analyzed for the activity concentrations of Ra, Ra, Th, and K and for their Rn exhalation rate. The sampled materials consisted of gypsum products, aerated concrete, sand-lime and clay bricks, mortars and concrete, representing about 95% of the stony building materials used in the construction of Dutch homes. The laboratory analyses were performed according to two well-documented standard procedures, the interlaboratory reproducibility of which is found to be within 5% on average. The highest radionuclide concentrations were found in a porous inner wall brick to which fly ash was added. The second highest were clay bricks with average Ra and Ra levels around 40 Bq kg. Concrete and mortar show the highest exhalation rates with a fairly broad range of 1 to 13 microBq (kg s). Low natural radioactivity levels are associated with either natural gypsum (products) or gypsum from flue gas desulphurization units, and low exhalation rates with clay bricks. To evaluate the radiological impact the radioactivity concentrations in each sample were combined into a so-called dose factor, representing the absorbed dose rate in a room with a floor, walls and ceiling of 20 cm of the material in question. For that purpose, calculations with the computer codes MCNP, Marmer and MicroShield on the specific absorbed dose rates were incorporated in the paper. The results of these codes corresponded within 6% and average values were calculated at 0.90, 1.10, and 0.080 nGy h per Bq kg for the U series, the Th series, and K, respectively. Model calculations on the external dose rate, based on the incidence of the various building materials in 1,336 living rooms, are in accordance with measured data.
Air Pollutants, Radioactive↗
Radon testing in households with a residential smoker--United States, 1993-1994.
Epidemiologic investigations of underground miners and studies of alpha particle carcinogenesis among laboratory animals suggest that exposure to the radioactive decay products (progeny) of radon is an important risk factor for lung cancer. Persons who smoke cigarettes and are exposed to these radon progeny have a substantially greater risk for developing malignancy than nonsmokers. Residential radon concentrations above the U.S. Environmental Protection Agency's (EPA) action level of 4 pCi/L are the primary sources of exposure among the general population. EPA and the Public Health Service promote home testing for radon, especially in households with a person who smokes. However, it is unknown whether households that contain smokers are more likely than those without smokers to test for radon. To characterize radon testing practices of households that contain a person who smokes within the dwelling (i.e., residential smoker), CDC analyzed survey data from the National Health Interview Survey (NHIS). This report summarizes the results of this analysis, which indicates that households with a residential smoker are significantly less likely to test for radon than those without smokers.
Air Pollutants, Radioactive↗
Radon exposures from the use of natural gas in buildings.
Low levels of natural radioactivity in the ground produce radon-222 and its decay products which can be entrained with gas streams and become distributed with gas supplies to commercial and domestic users. Levels of radon in blended gas received by most users are comparable with the levels that are present naturally in buildings as a result of ingress from the ground and this is further diluted during the combustion process. For typical rates of gas usage with an average radon level of about 200 Bq x m(-3), the estimated dose from the use of natural gas is estimated at 4 microSv, less than 1% of the dose from radon exposure at the average level in UK homes. Commercial users may receive somewhat higher doses, and the estimate for a critical group is a few tens of microsievert. The total radon emission to the environment is estimated at about 10(13) Bq x y(-1) which represents less than 10(-4) of the natural emission rate from the ground. There is some variability of radon levels in gas from different sources and it would be prudent to keep this source of exposure under review. A standard sampling and measurement protocol has been developed in conjunction with a technical group representing the industry.
Air Pollutants, Radioactive↗
Radon exposure assessment and dosimetry applied to epidemiology and risk estimation.
Epidemiological studies of underground miners provide the primary basis for radon risk estimates for indoor exposures as well as mine exposures. A major source of uncertainty in these risk estimates is the uncertainty in radon progeny exposure estimates for the miners. Often the exposure information is very incomplete, and exposure estimation must rely on interpolations, extrapolations and reconstruction of mining conditions decades before, which might differ markedly from those in more recent times. Many of the measurements that were carried out-commonly for health protection purposes-are not likely to be representative of actual exposures. Early monitoring was often of radon gas rather than of the progeny, so that quantifying exposure requires an estimate of the equilibrium fraction under the conditions existing at the time of the reported measurement. In addition to the uncertainty in radon progeny exposure, doses from gamma radiation, inhaled radioactive dust, and thoron progeny have historically been neglected. These may induce a systematic bias in risk estimates and add to the overall uncertainty in risk estimates derived from the miner studies. Unlike other radiogenic cancer risk estimates, numerical risk estimates derived for radon from epidemiology are usually expressed as a risk per unit exposure rather than as a risk per unit dose to a target tissue. Nevertheless, dosimetric considerations are important when trying to compare risks under different exposure conditions, e.g. in mines and homes. A recent comparative assessment of exposure conditions indicates that, for equal radon progeny exposures, the dose in homes is about the same as in mines. Thus, neglecting other possible differences, such as the presence in mines of other potential airborne carcinogens, the risk per unit progeny exposure should be about the same for indoor exposures as observed in miners. Results of case-control studies of lung cancer incidence in homes monitored for radon are reasonably consistent with what would be projected from miner studies. Measurements of exposure in these indoor case-control studies rely on different types of detectors than those used in mines, and the estimates of exposure are again a major source of uncertainty in these studies.
Air Pollutants, Radioactive↗
Estimated risks of radon-induced lung cancer for different exposure profiles based on the new EPA model.
Radon is a naturally occurring radioactive gas. When inhaled, radon can cause mutations that lead to lung cancer. Some new epidemiologic studies indicate that indoor radon is a public health problem. The BEIR VI report outlined its preferred two risk models for the combined effects of smoking and exposure to radon progeny, and listed the estimated risk to ever-smokers and never-smokers of both sexes due to lifetime exposure. However, exposures for shorter periods of time are of practical interest since exposure to elevated levels of radon may occur and end at any age. This study aims to produce practical tables of lifetime relative risks for exposures between any two age intervals from 0 to 110, and for various radon concentrations found in homes from 100 to 1,000 Bq m(-3). The calculations are based on the risk model developed recently by U.S. Environmental Protection Agency. The EPA's risk model is a single model that gives risk values midway between those obtained from the two BEIR VI preferred models. The detailed tables provide a clearer view of the age groups at higher risk and the effect of exposure duration. The results will help radiation protection practitioners to better communicate indoor radon risk to members of the public.
Adolescent↗
Radon survey in the high natural radiation region of Niska Banja, Serbia.
A radon survey has been carried out around the town of Niska Banja (Serbia) in a region partly located over travertine formations, showing an enhanced level of natural radioactivity. Outdoor and indoor radon concentrations were measured seasonally over the whole year, using CR-39 diffusion type radon detectors. Outdoor measurements were performed at 56 points distributed over both travertine and alluvium sediment formations. Indoor radon concentrations were measured in 102 living rooms and bedrooms of 65 family houses. In about 50% of all measurement sites, radon concentration was measured over each season separately, making it possible to estimate seasonal variations, which were then used to correct values measured over different periods, and to estimate annual values. The average annual indoor radon concentration was estimated at over 1500 Bq/m3 and at about 650 Bq/m3 in parts of Niska Banja located over travertine and alluvium sediment formations, respectively, with maximum values exceeding 6000 Bq/m3. The average value of outdoor annual radon concentration was 57 Bq/m3, with a maximum value of 168 Bq/m3. The high values of indoor and outdoor radon concentrations found at Niska Banja make this region a high natural background radiation area. Statistical analysis of our data confirms that the level of indoor radon concentration depends primarily on the underlying soil and building characteristics.
Air Pollutants, Radioactive↗