Abstract The majority of radon measurements in the built environment are made over sub-year periods and are then generally seasonally corrected (i.e. scaled by an appropriate seasonal correction factor (SCF)) to estimate the annual average radon concentration. SCFs are statistically derived and assume an underlying annual cycle, reflecting the widely observed seasonal variation in indoor radon concentrations. In the UK, Public Health England has pioneered the calculation and use of a national SCF set using an annual sinusoidal model for variations in radon concentration and averaging across the entire country. To test the validity of that model, a 4 year record of weekly radon data from four houses in Brixworth (Northamptonshire, UK) was analysed in conjunction with corresponding weather data for the period from a nearby weather station. The radon data showed a statistically significant annual cycle comprising both annual sinusoidal and second harmonic (i.e. 6 month period) terms. Two sets of SCFs were calculated: first, using a conventional annual sinusoidal model that explained 21.2% of the variance in the radon data; and, secondly, a second harmonic term was included in the model that explained 24.6% of the variance. This represents an improvement of 3.4 percentage points (15.9%) and, thus, will result in better SCFs.

Abstract Understanding the behaviour of fluids in hydrothermal systems is a key factor in volcano monitoring. Measuring gas emissions in volcanic areas is strategic for detecting and interpreting precursory signals of variations in volcanic activity. The role of radon as a potential precursor of earthquakes has been extensively debated. However, radon anomalies appear to be better suited to forecast eruptive episodes as we know the loci of volcanic eruptions and we can follow the evolution of volcanic activity. Radon mapping is an effective tool in assessing diffuse and concentrated degassing at the surface. We hereby summarize the in-soil radon emissions collected worldwide and further discuss a collection of data on our key targets. These are closed-conduit and open-conduit volcanoes: Vesuvius (Italy) and La Soufrière (Guadeloupe, Lesser Antilles), Stromboli (Italy) and Villarrica (Chile), respectively. In all the above volcanoes, faults and fracture systems control radon degassing. Automatic and real-time measurements help us to detect major changes in volcanic activity. We present and discuss the radon time series associated with the last effusive eruption at Stromboli. Spectral analyses reveal diurnal and semi-diurnal cycles being probably modulated by atmospheric variations. Multiple linear regression (MLR) analyses have been performed by filtering the radon signals from the effects of local environmental parameters. The residuals do not show particular variations or precursory peaks as the gases have been released from this open-conduit volcano before the onset of the effusive phase (7 August 2014). It is finally emphasized that radon is not the sole precursor, and we should also rely on other geochemical and geophysical parameters. In this perspective, we propose a methodological procedure that can contribute to improving volcano surveillance in an attempt to mitigate volcanic risk.

Abstract This paper presents selected issues related to the use of 222 Rn in therapeutic treatments. Radon is a radioactive element whose usage in medicine for more than 100 years is based on the radiation hormesis theory. However, owing to the radioactive character of this element and the fact that its alpha-radioactive decay is the source of other radionuclides, its therapeutic application has been raising serious doubts. The author points to potential sources and carriers of radon in the environment that could supply radon for use in a variety of therapies. Except for centuries-long tradition of using radon groundwaters, and later also the air in caves and underground workings, the author would also like to focus on soil air, which is still underestimated as a source of radon. The text presents different methods of obtaining this radioactive gas from groundwaters, the air in caves, mining galleries and soil air, and it presents new possibilities in this field. The author also discusses problems related to the transportation and storage of radon obtained from the environment. Within radon-prone areas, it is often necessary to de-radon groundwaters that are intended for human consumption and household usage. Also, dry radon wells are used to prevent radon migration from the ground into residential buildings. The author proposes using radon released from radon groundwaters and amassed in dry radon wells for radonotherapy treatments. Thanks to this, it is possible to reduce the cost of radiological protection of people within radon-prone areas while still exploiting the 222 Rn obtained for a variety of therapies. With regard to the ongoing and still unsettled dispute concerning the beneficial or detrimental impact of radon on the human organism, the author puts special emphasis on the necessity of strictly monitoring both the activity concentration of 222 Rn in media used for therapeutic treatments and of its radioactive decay products. Monitoring should be also extended to the environments in which such treatments are delivered (inhalatoriums, baths, saunas, showers, pools and other facilities), as well as to the patients – during and after the radonotherapy treatments. It is also essential to monitor the dose of radon and its daughters that is received by persons undergoing radon therapy. This should facilitate the assessment of the effectiveness of these treatments, which may contribute to a fuller understanding of the mechanisms of radon impact, and ionizing radiation in general, on the human organism. This will make it easier to ultimately confirm or reject the radiation hormesis theory. It is also essential to monitor the effective dose that is received by medical and technical staff employed to deliver the radonotherapy treatments.

Abstract Radon is generally regarded as a naturally occurring radiological hazard but we report here measurements of significant, hazardous radon concentrations that arise from man-made sources: for example, radium-dial watches. This study is an examination and assessment of health risks from radium and uranium found in historical artefacts, and the radon that emanates from them. This includes radium-dial watches, the main focus, plus clocks, aircraft instruments, and ornaments and artefacts made of uranium glass/uranium-glazed. Such objects were very popular in the 1930s and 1940s, and are still readily available today. A collection of 30 radium-dial pocket and wrist watches was measured and shown to be capable of giving rise to radon concentrations two orders of magnitude greater than the UK Domestic Action Level of 200 Bq m −3 in unventilated or poorly ventilated rooms. Furthermore, individual watches are capable of giving rise to radon concentrations in excess of the UK Domestic Action Level. We also highlight a gap in remediation protocols, which are focused on preventing radon entering buildings from outside, with regard to internally generated radon hazards. Radon as arising from man-made objects, such as radium-dial watches, should be considered appropriately in radon protocols and guidelines.

Abstract Effective radium-226 concentration, EC Ra , is the product of radium activity concentration, C Ra , multiplied by the emanation coefficient, E , which is probability of producing a radon-222 atom in the pore spaces. It is measured by accumulation experiments in the laboratory, achieved routinely for a sample mass >50 g using scintillation flasks to measure the radon concentration. We report on 3370 EC Ra values obtained from more than 11 800 such experiments. Rocks ( n =1351) have a mean EC Ra value of 1.9±0.1 Bq kg −1 (90% of data in the range 0.11–35 Bq kg −1 ), while soils ( n =1524) have a mean EC Ra value of 7.5±0.2 Bq kg −1 (90% of data between 1.4 and 28 Bq kg −1 ). Using this large dataset, we establish that the spatial structure of EC Ra is meaningful in geology or sedimentology. For plants ( n =85), EC Ra is generally <1 Bq kg −1 , but values of larger than 10 Bq kg −1 are also observed. Dedicated experiments were performed to measure emanation, E , in plants, and we obtained values of 0.86±0.04 compared with 0.24±0.04 for sands, which leads to estimates of the radium-226 soil-to-plant transfer ratio. For most measured animal bones ( n =26), EC Ra is >1 Bq kg −1 . Therefore, EC Ra appears essential for radon modelling, health hazard assessment and also in evaluating the transfer of radium-226 to the biosphere.

Abstract Radon ( 222 Rn) has been highlighted by a number of authors as a significant public health concern. For example, it is the second most significant cause of lung cancer after tobacco smoking ( c. 1000–2000 and 21 000 deaths per year in the UK and USA, respectively), yet a very high proportion of the general public appears to be unaware of the risk. This chapter deals with topical radon issues, such as: radon in the workplace; radon in homes; exposure to radon during leisure activities; radon and water; measurement and monitoring; seasonal correction; remediation; cancer risks; cost–benefit analysis and cost-effectiveness; mapping; future policies; and further research. This assessment of the state of radon research is focused on the UK as an example of a country where radon has been on the governmental agenda since the late 1970s, but also highlights radon issues throughout the world in, for example, the USA, Europe and Asia.

Abstract Year-long continuous radon monitoring was carried out (using Sarad Radon Scout devices) in a dwelling with high radon levels in the karst region of Slovenia. Two living rooms were selected: one on the ground floor with normal housework activities; and the second, on the first floor, closed and unattended. Meteorological data were also recorded. The following seasonal geometric means of radon activity concentration (kBq m −3 ) have been found: 6.28 ×/: 3.05 for spring, 1.25 ×/: 3.78 for summer, 5.17 ×/: 2.03 kBq m −3 for autumn and 9.83 ×/: 1.48 for winter on the ground floor; and 1.43 ×/: 3.71 for spring, 0.168 ×/: 2.49 for summer, 1.08 ×/: 2.39 for autumn and 2.08 ×/: 2.14 for winter on the first floor. Results are supported by additional radon measurements in other rooms; and in water the results indicate a strong radon source associated with an underground karst shaft.

Abstract In 2014, the Geological Survey of Austria (GBA) published – in cooperation with further national institutions – an overview map on radionuclides in groundwater, rocks and stream sediments at a scale of 1:500 000 with explanatory notes. In the frame of this activity, the uranium, 228 Ra, 226 Ra, 222 Rn, 210 Pb and 210 Po analyses in groundwater studies made by the Austrian Agency for Health and Food Safety (AGES) and Environment Agency of Austria (Umweltbundesamt), as well as the uranium and thorium analyses of stream sediments of the GBA and whole-rock analyses from different sources, were evaluated statistically. Furthermore, the GBA’s comprehensive airborne radiometric data were exploited. The aim of this study was to work out typical spectra of the radionuclide content in the groundwater and aquifers of different geological settings. It appeared that the concentration of 222 Rn in groundwater depends significantly on the uranium content of the aquifer. In contrast to this, the other radionuclides in groundwater did not show a clear correlation with uranium and thorium in the subsurface geology. Concerning 228 Ra, 226 Ra, 210 Pb and 210 Po, the lack of relationship to the subsurface composition seems to be a result of the low concentrations in groundwater. With respect to uranium in groundwater, there is a mixed situation: on the one hand, high uranium concentrations in groundwater can be observed in the Alps in regions with uranium bearing orthogneisses. On the other hand, in sediment basins of NE Austria where the underlying geology contains little uranium. Whether this is caused by special geological features combined with the given low precipitation or by the extensive agriculture (uranium from phosphate fertilizer) is under examination. Concerning the threshold values of the radionuclides in groundwater (radiation), no exceedance could be observed. In spite of this, the concentration of the heavy metal uranium sometimes exceeded the threshold value of 15 µg l −1 : this is especially true for the regions mentioned above. In addition, an attempt was made to compare the Austrian values with data from neighbouring countries. It became clear that only a few published datasets exist that are comparable. Radon analyses of soil gas in the Czech Republic and Bavaria show the same geological patterns as the Austrian radon analyses of the groundwater. In addition, to enable the reader to compare the Austrian data with datasets from other countries, additional tables are included here for all types of data. They show the statistic distributions of different geological classes in a coordinated way. Supplementary material: An Austrian map and explanation notes showing the uranium content of the underground and radionuclides in ground water are available at https://doi.org/10.6084/m9.figshare.c.3780170

Although mineral hazards are generally not well established in the public consciousness compared to other natural hazards, they can adversely affect public health and safety and the environment. The term “mineral hazards,” as used here, includes certain naturally occurring earth materials and sites of man-made activities related to them, such as mining and oil drilling. Since the 1990s, the California Geological Survey has conducted many studies of mineral hazards in California in response to an increasing number of requests from government agencies, private industry, and the public. These studies have focused mostly on naturally occurring asbestos, radon, and various metals, such as mercury and cadmium. The mineral-hazard maps and companion reports produced from these studies are typically at statewide and regional scales. They are designed for use by nongeoscientists and geoscientists alike in an effort to educate these groups about mineral hazards and to help in mitigation of those hazards. These products indicate the likelihood of the occurrence of a mineral hazard at a given location, but not the associated health risk. Geographic information systems (GIS) are used to manage and analyze data, and to design the maps. The variety of products developed ranges from traditional paper maps to thematic digital layers for use in a GIS. This range of products increases the likelihood that a greater number of people will use the information. The maps and reports have been used in many applications, and additional applications await development as awareness of mineral hazards and the need for mitigation of them increase.

To better understand regional variations in radon occurrences, the Kentucky Geological Survey (KGS) is working in partnership with the University of Kentucky College of Nursing’s Clean Indoor Air Partnership to examine spatial and statistical associations between residential radon measurements and near-surface geologic rock formations that may serve as a radon source or pathway. A primary goal is to understand potential risk for population-level radon exposure. The Clean Indoor Air Partnership has been investigating the associations among radon prevalence, secondhand smoke, and lung cancer risk reduction. KGS and faculty in the College of Nursing formed a partnership to better understand the spatial variability of radon incidence by using a geologically referenced radon data set. Two studies have taken place, and one is currently under way. To facilitate the collaboration, a pilot study by KGS compared radon values to geologic formations in Boyle County, Kentucky. This study helped to communicate radon occurrence less in terms of political boundaries and more in terms of physical phenomena. The next phase of collaboration is a statistical analysis of the radon data in higher-population areas (central and northern Kentucky) to define those geologic units spatially associated with the high radon values. This will enable College of Nursing researchers to systematically target areas with the most potential for high radon exposure levels. The latest collaboration will create five county maps using residential radon testing values (supplied by the College of Nursing) to advance radon education and awareness and reduce lung cancer risk in Kentucky.

Abstract Determining the timescales of magma degassing is essential for understanding the mechanisms controlling the eruption style and the dynamics of magmatic systems. Towards this end, we measured 210 Pb– 226 Ra disequilibria in andesite lavas erupted from Volcán de Colima between 1998 and 2010. ( 210 Pb/ 226 Ra) 0 activity ratios range from 0.86 to 1.09, and are best explained in terms of 222 Rn degassing and accumulation. The range in 210 Pb deficits indicates that the timescales of 222 Rn degassing did not exceed 11 years. 210 Pb excesses are rare and small (<10%), which signifies that 222 Rn degassing is more effective than 210 Pb accumulation in this intermediate system despite the relatively low gas output at the surface. The absence of significant 210 Pb excesses strongly suggests that the volcanic activity results from episodic ascent of small magma batches through the vapour-saturated section of the magmatic system. Overall, the degassing models based on 210 Pb– 226 Ra disequilibrium suggest an open and complex subvolcanic magmatic system comprising several conduits in which multiple magma batches reside for up to 10 years. Shifts from effusive to explosive Vulcanian eruptive phases are not related to changes in degassing mode on timescales resolvable using 210 Pb– 226 Ra disequilibria.

Abstract Most of Oregon has been mapped as having low radon potential. Overall, elevated levels of indoor radon are found in only 4% of Oregon homes compared to 8% of homes nationally. Most maps show Portland, Oregon’s largest city, as having low to moderate potential for indoor radon. Using data collected by the Oregon Health Division’s Radiation Protection Services Section, we found Portland to have elevated radon values in 22% of homes. A radon potential map has been produced for 39 zip code regions of Portland based on the rank sums of maximum radon values, average indoor radon values, and the percentage of homes with radon values >4 pCi/1. Eight zip codes have high, 15 moderate, and 16 low radon potential. The maps were constructed by taking the indoor radon values from 1,135 homes, categorizing the data in terms of radon values, and plotting the points geographically by zip codes. Trends became obvious when geologic maps were compared to the areas of radon potential. Most of the high potential sites lie on highly permeable Missoula flood sediments. The data and map of radon potential were presented to the public through television and radio interviews and newspaper articles in June of 1994. The public, already familiar with the zip codes, could understand how to use the map. People in high to moderate categories were strongly encouraged to test their homes. A telephone number was given to receive free information on radon testing and mitigation.

Shear zones and bedrock units as thin as 3 to 4 m in width can be detected using radon and equivalent uranium (eU) concentrations in soils overlying the Hylas zone area, Virginia. Soil radon concentrations in the area range from 144 to 12,081 pCi/L, with distinct contrasts in concentrations among many of the rock types. Equivalent uranium concentrations range from 0.4 to 9.8 ppm; they also reflect bedrock geology but less distinctly than soil radon, which is subject to surficial mechanical and chemical processes. The formation of saprolite and subsequent soil processes produce variability in uranium concentrations and consequently contacts and other fine geologic details can be obscured near the surface. Soil radon analyses at a depth of 75 cm, and using small (20 ml) samples, largely circumvent these problems and can be used as an effective geologic mapping tool in covered areas, provided that (1) there is a uranium concentration contrast in the bedrock, and that (2) the soil is derived directly from bedrock. The scale of variability of radon in soil gas indicates that radon potential maps should be constructed on the basis of geology rather than political divisions.