Cost assessment of ventilation and averted dose due to radon in dwellings

The inhalation dose due to radon and its progenies could be averted by ventilation in dwellings; however, on the other hand the increased ventilation augments the heating cost. Therefore a cost-benefit analysis could contribute to optimise the ventilation rate. In our current work we applied our former defined parameters of the optimising procedure to assess the optimised ventilation and radon concentration in dwellings with average parameters. To assess the inhalation dose rates the time-dependent concentrations of all the progenies were calculated in case of periodic and continuous ventilation as well, at three different radon entry rates (5, 10, 20kBqh(-1)). The optimal ventilation rates in case of continuous ventilation are 0.22, 0.40 and 0.66h(-1), respectively. By these conditions the optimal radon concentration takes 160-210Bqm(-3). According to the more detailed analysis the periodic ventilation gives, in general, a better solution than the continuous one. The Monte Carlo simulations provided a large uncertainty; therefore, before the practical application of the results the uncertainty should be decreased taken into account the local conditions.     

Exposure to radon in the Gadime Cave, Kosovo

Air radon concentration was measured in summer and winter at 11 points along the tourist guided route in the Gadime Cave in Kosovo using alpha scintillation cells and etched track detectors. At two points in summer, values higher than 1700Bqm(-3) were observed; they otherwise were in the range 400-1000Bqm(-3). Values were lower in winter. The effective dose received by a person during a 90min visit is 3.7muSv in summer and 2.5muSv in winter. For a tourist guide the annual effective dose is less than 3.5mSv.     

Natural radioactivity and radon exhalation in building materials used in Italian dwellings

Forty-two samples of building materials commonly used in Italian dwellings were surveyed for natural radioactivity. External (gamma), as defined and used by the European Commission, and internal (alpha) hazard indexes were calculated and radon specific exhalation rate and emanation fraction were measured. The accumulation method, by using the E-PERM electret ion chambers, was employed to determine specific exhalation rates of 222Rn. Several of the materials had hazard indexes that exceeded the European Commission limit values. However, it was evident that limit values for internal hazard indexes set based on Rn emanation should take into account the properties and use of the materials. For example, Rn emanation from basalt and glazed tiles was substantially lower than the Rn emanation from other materials with similar hazard indexes. Clearly there is need for improved guidelines and regulations in this area.     

Associations between grab sample and integrated radon measurements in dwellings in Maine and Texas

Radon concentrations were measured in several locations in each of approximately 100 dwellings in central Maine and in Houston, TX. Integrated samples were taken during the heating (or cooling) seasons with commercially available passive alpha track devices, while grab samples were taken at the time of integrated sampler deployment. It was found that both indoor and outdoor measurements in both areas were distributed log normally, and that the geometric mean of indoor measurements in Maine was three times higher than that of corresponding measurements in the Houston area. It was also noted that the mean of the indoor grab sample measurements was not significantly different from the mean of the indoor integrated measurements, and that the degree of correlation between the grab samples and a given indoor integrated sample was nearly as good as between integrated samples taken at different living area locations.     

Leaded gasoline — A cause of cancer

In the course of earlier tests the authors had found that the cancer mortality among 231 adult persons living adjacent to an automobile road was much higher than among persons living in a traffic-free section of the same town. Fifty-nine of the above individuals residing adjacent to the automobile road had been treated with calcium EDTA to eliminate lead. Only one of these later died of cancer. Of the persons who were not treated with calcium EDTA, on the other hand, 30 died of cancer, or ten times more percentage-wise.The existence of small lead deposits as well as the health-impairing effect of lead were demonstrated by measurements of lead and delta-aminolaevulinic acid in urine. After treatment with calcium EDTA, the lead content, as well as the amount of delta-aminolaevulinic acid, became normal. The concentrations of lead were found to be greater in suspended dust particles and in sediment dust along the automobile artery than elsewhere in the town.These findings, together with many other reports in the medical literature lead to the suspicion that lead in automobile gasoline, combined with other carcinogenic substances in automotive exhaust gases, increases the incidence of cancer.     

Factors affecting metal toxicity to (and accumulation by) aquatic organisms — Overview

This literature review encompasses aquatic environmental toxicities of metals and metalloids. The emphasis is on the influencing factors on metal toxicity to aquatic organisms. The effects of environmental factors on metal uptake are also discussed. The factors can be divided into biotic and abiotic. The biotic factors include tolerance, size and life stages, species, and nutrition related to the test organisms. The abiotic factors include organic substances, pH, temperature, alkalinity and hardness, inorganic ligands, interactions, sediments, and others. These factors can alter metal toxicity in the aquatic environment substantially, mostly causing attenuating effect. The literature shows divergent results. For example, the interactions between Cd and Zn were reported to be synergistic by some researchers and antagonistic by others. It is recommended that environmental hazard assessment takes into consideration the results of standard toxicity tests and site-specific conditions which can moderate metal toxicity considerably.     

An overview of an indoor radon study carried out in dwellings in India and Bangladesh during the last decade using solid state nuclear track detectors

This paper reports on radon concentrations in dwellings from fifty different locations of India. The incorporated data were obtained using the passive solid state nuclear track detector technique. The estimated geometric mean value for India is 67.1 Bq m(-3). Chuadanga in Bangladesh had the lowest observed indoor radon concentration of 27.3 Bq m(-3) and Una in the northern part of India had the highest concentration of 281.5 Bq m(-3). This paper discusses the national geometrical mean value in terms of the national geometric mean values of other countries and also in terms of the geological influence. The estimated indoor radon levels are compared with the indoor radon levels as recommended by the International Commission on Radiation Protection (ICRP). It was observed that there are several locations in India where dwellings have higher indoor radon levels than the ICRP recommended value and requires some sort of intervention from regulating authorities. The mean value for indoor radon level given in the report of UNSCEAR 2000 for India needs to be revised.     

Dose estimation and radon action level problems due to nanosize radon progeny aerosols in underground manganese ore mine

One of the essential parameters influencing of the dose conversion factor is the ratio of unattached short-lived radon progeny. This may differ from the value identified for indoor conditions when considering special workplaces such as mines. Inevitably, application of the dose conversion factors used in surface workplaces considerably reduces the reliability of dose estimation in the case of mines.This paper surveyed the concentration of radon and its short-lived radon progeny and identified the unattached fraction of short-lived radon progeny. As well equilibrium factor during the month of August was calculated simultaneously at two extraction faces in a manganese ore mine.During working hours the average radon concentrations were 220 Bq m⁻³ and 530 Bq m⁻³ at Faces 1 and 2; the average short-lived progeny concentration was 90 Bq m⁻³ and 190 Bq m⁻³, the average equilibrium factors were 0.46 and 0.36, and the average unattached fractions were 0.21 and 0.17, respectively. The calculated dose conversion factor was between 9 and 27 mSv WLM⁻¹, but higher values could also be possible.     

Mapping of the geogenic radon potential in France to improve radon risk management: methodology and first application to region Bourgogne

In order to improve regulatory tools for radon risk management in France, a harmonised methodology to derive a single map of the geogenic radon potential has been developed. This approach consists of determining the capacity of the geological units to produce radon and to facilitate its transfer to the atmosphere, based on the interpretation of existing geological data. This approach is firstly based on a classification of the geological units according to their uranium (U) content, to create a radon source potential map. This initial map is then improved by taking into account the main additional parameters, such as fault lines, which control the preferential pathways of radon through the ground and which can increase the radon levels in soils. The implementation of this methodology to the whole French territory is currently in progress. We present here the results obtained in one region (Bourgogne, Massif Central) which displays significant variations of the geogenic radon potential. The map obtained leads to a more precise zoning than the scale of the existing map of radon priority areas currently based solely on administrative boundaries.     

Soil radium, soil gas radon and indoor radon empirical relationships to assist in post-closure impact assessment related to near-surface radioactive waste disposal

Least squares (LS), Theil’s (TS) and weighted total least squares (WTLS) regression analysis methods are used to develop empirical relationships between radium in the ground, radon in soil and radon in dwellings to assist in the post-closure assessment of indoor radon related to near-surface radioactive waste disposal at the Low Level Waste Repository in England. The data sets used are (i) estimated ²²⁶Ra in the <2 mm fraction of topsoils (eRa226) derived from equivalent uranium (eU) from airborne gamma spectrometry data, (ii) eRa226 derived from measurements of uranium in soil geochemical samples, (iii) soil gas radon and (iv) indoor radon data. For models comparing indoor radon and (i) eRa226 derived from airborne eU data and (ii) soil gas radon data, some of the geological groupings have significant slopes. For these groupings there is reasonable agreement in slope and intercept between the three regression analysis methods (LS, TS and WTLS). Relationships between radon in dwellings and radium in the ground or radon in soil differ depending on the characteristics of the underlying geological units, with more permeable units having steeper slopes and higher indoor radon concentrations for a given radium or soil gas radon concentration in the ground. The regression models comparing indoor radon with soil gas radon have intercepts close to 5 Bq m⁻³ whilst the intercepts for those comparing indoor radon with eRa226 from airborne eU vary from about 20 Bq m⁻³ for a moderately permeable geological unit to about 40 Bq m⁻³ for highly permeable limestone, implying unrealistically high contributions to indoor radon from sources other than the ground. An intercept value of 5 Bq m⁻³ is assumed as an appropriate mean value for the UK for sources of indoor radon other than radon from the ground, based on examination of UK data. Comparison with published data used to derive an average indoor radon: soil ²²⁶Ra ratio shows that whereas the published data are generally clustered with no obvious correlation, the data from this study have substantially different relationships depending largely on the permeability of the underlying geology. Models for the relatively impermeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with lower indoor radon: soil ²²⁶Ra ratios, whilst the models for the permeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with higher than average indoor radon: soil ²²⁶Ra ratios.     

A theoretical approach to indoor radon and thoron distribution

A model based on the Finite Element Method was developed to simulate indoor behavior of radon ((222)Rn), thoron ((220)Rn) and their progeny, as well as, to calculate their spatial distributions. Since complex physical processes govern the distribution several simplifications were made in the presented model. Different locations of possible radon/thoron sources, diffusion of these gases, their radioactive decay, etc were taken into account. Influences of different parameters on thoron/radon as well as indoor distribution of their progeny, such as the geometry and room dimension, the presence of aerosols and their size distribution expressed through the diffusion coefficient, different kinds of ventilation, etc, were investigated. It has been found that radon is distributed homogeneously, while the thoron concentration is rather inhomogeneous and decreases exponentially with the distance from the source. Regardless of the source distribution, the distribution of radon was homogeneous, except at places near an air inlet and outlet. However, the distribution of thoron depends on the source distribution. If thoron emanates from walls or the floor, its concentration decreases with the distance from the wall. Moreover, the concentration gradient is much larger near walls. This suggests that the actual selection of the site effect should be taken into account when obtaining a representative value of indoor (220)Rn and their progeny for dose assessment. The simulation results of activities and their distribution were in accordance with the results of other studies and experiments.     

Air quality management in the WHO European Region — Results of a quality assurance and control programme on air quality monitoring (1994–2004)

Since the last decade the WHO Collaborating Centre for Air Quality Management and Air Pollution Control, Berlin, Germany, operates a quality assurance and control (QA/QC) programme on air quality monitoring in the WHO European Region. As main activity Intercomparison workshops have been established for air monitoring network laboratories on a regular basis to harmonise air quality measurements, analysis and calibration techniques. 36 air hygiene laboratories of public health and environmental institutions of 24 countries participated in twelve Intercomparisons between 1994 and 2004. The majority was carried out for NO, NO₂, SO₂ and O₃. The results were predominantly satisfactory for automatic methods. The results of manual methods were mainly in a good, and for several concentration levels partly very good accordance with the data obtained by the monitors.     

Regional geology and radon variability in buildings

Radon concentrations in dwellings vary by more than two orders of magnitude. Predicting where and when concentrations are likely to be high requires studying the variability of the contributors to radon in buildings. Among common sources, geological factors (water supply and substrate) are the most variable, whereas building materials are much less variable. Ventillation variation among houses is generally responsible for radon variations comparable to those introduced by building materials, but it is more significant at lower ventilation rates. In some regions with relatively high proportions of houses with elevated radon concentrations, mappable geological factors are associated with most cases of high radon concentrations. However, a priori identification of rock types likely to be implicated is likely to be successful in only a few cases.     

Dissolved radon and gaseous mercury in the Mediterranean seawater

Vertical profiles of radioactive radon gas ((222)Rn) and dissolved gaseous mercury (DGM) in seawater in the Mediterranean Basin have been measured. They were found in the range 1.7-19.3 Bq m(-3) and 22-200 ng m(-3), respectively, at the bottom and 2.0-20.0 Bq m(-3) and 6-80 ng m(-3), respectively, at the surface. Preliminary results indicate a positive correlation between concentrations of both gases at some locations, but not at others. Further analyses will be performed, after (226)Ra contents in sediment and water have been determined, taking into account environmental parameters such as air and water temperatures, barometric pressure and water flow, in order to better interpret these profiles.     

Natural radionuclide content in building materials and gamma dose rate in dwellings in Cuba

An extensive research project to investigate the radioactive properties of Cuban building materials was carried out because there is a lack of information on the radioactivity of such materials in Cuba. In the framework of this project 44 samples of commonly used raw materials and building products were collected in five Cuban provinces. The activity concentrations of natural radionuclides were determined by gamma ray spectrometry using a p-type coaxial high purity germanium detector and their mean values were in the ranges: 9-857Bqkg(-1) for (40)K; 6-57Bqkg(-1) for (226)Ra; and 1.2-22Bqkg(-1) for (232)Th. The radium equivalent activity in the 44 samples varied from 4Bqkg(-1) (wood) to 272Bqkg(-1) (brick). A high pressure ionisation chamber was used to measure the indoor absorbed dose rate in 543 dwellings and workplaces in five Cuban provinces. The average absorbed dose rates in air ranged from 43nGyh(-1) (Holguín) to 73nGyh(-1) (Camagüey) and the corresponding population-weighted annual effective dose due to external gamma radiation was estimated to be 145+/-40microSv. This value is 51% lower than the effective dose due to internal exposure from inhalation of decay products of (222)Rn and (220)Rn and it is 16% higher than the calculated value for the typical room geometry of a Cuban house.     

Two error components model for measurement error: application to radon in homes

In this paper, a simple model for analysing variability in radon concentrations in homes is tested. The approach used here involves two error components, representing additive and multiplicative errors, together with variation between-houses. We use a Bayesian approach for our analysis and apply this model to two datasets of repeat radon measurements in homes; one based on 3-month long measurements for which the original measurements were close to the current UK Radon Action Level (200 Bq m⁻³), and the other based on 6-month measurement data (from regional and national surveys), for which the original measurements cover a wide range of radon concentrations, down to very low levels. The model with two error components provides a better fit to these datasets than does a model based on solely multiplicative errors.     

Radionuclide content of building materials and associated gamma dose rates in Egyptian dwellings

Studies have been carried out to determine the natural radioactivity in some building materials (bricks, tiles, marble and ceramics) and their associated radiation hazard. The radioactivity concentrations of ²²⁶Ra ²³²Th and ⁴⁰K were measured using a gamma spectrometer with a Hp–Ge detector. The activities of ²³⁸U and ²³⁴U were measured using an alpha-spectrometer with a surface barrier detector after applying a radiochemical procedure. The ²³⁴U/²³⁸U isotopic ratios were calculated. The radium equivalent activities and the radiation hazard index associated with the natural radionuclides were calculated. A computer program was developed and applied to calculate the dose rate a person will receive from the walls of a room constructed from the studied building materials.     

Ventilation behaviour and indoor air problems in different types of newly built dwellings

In four types of newly built single family dwellings and in apartments of a block of flats in the Netherlands, the behaviour and motivations of the occupants are studied with respect to their response to heating and ventilation, as well as their judgment on indoor air and climate variables such as tobacco smoke, cooking smells, vapour, mould, dryness, draft and temperature. Knowing the behaviour of the occupants and the building characteristics, estimates are made on the air flows through the dwellings and these air flows are related to stated indoor air and climate problems. The results from the field studies provide recommendations for architects and developers of dwellings and installations and to researchers working on this type of field study. A thesis is proposed that people still define something as a problem, if the resolution offered to solve the problem is also experienced as undesirable.