A cost-effectiveness analysis of radon protection methods in domestic properties: a comparative case study in Brixworth, Northamptonshire, UK

Building regulations in the UK have since 1992 required that radon-proof membranes be installed in new domestic properties to protect residents against the adverse effects of radon. This study compares the cost-effectiveness of the current regulatory regime with an alternative that would entail new properties being tested for radon after construction, and being remediated if necessary. The alternative regime is found to be more cost-effective for a sample of properties in Brixworth, Northamptonshire, UK. For this regime, the central estimate of cost per quality-adjusted life-year gained, the measure of cost-effectiveness used, is 2869 pounds compared to 6182 pounds for installing membranes, results suggesting a case for re-examining the current regulations on radon protection in new properties. Pilot studies will, however, be needed to consider how different means of protecting residents of new properties against radon might operate in practice and to provide improved evidence on their relative cost-effectiveness.     

The cost effectiveness of radon reduction programmes in domestic housing in England and Wales: The impact of improved radon mapping and housing trends

In the UK, excessive levels of radon gas have been detected in domestic housing. Areas where 1% of existing homes were found to be over the Action Level of 200 Bq · m^− 3 were declared to be Radon Affected Areas. Building Regulations have been introduced which require that, for areas where between 3% and 10% of existing houses are above the Action Level, new homes should be built with basic radon protection using a membrane, and that, where 10% or more of existing homes exceed this level, new homes should be built with full radon protection.Initially these affected areas followed administrative boundaries, known as Counties. However, with increasing numbers of measurements of radon levels in domestic homes recorded in the national database, these areas have been successively refined into smaller units – 5 km grid squares in 1999, down to 1 km grid squares in 2007.One result is the identification of small areas with raised radon levels within regions where previously no problem had been identified. In addition, some parts of areas that were previously considered radon affected are now considered low, or no, risk. Our analysis suggests that the net result of improved mapping is to increase the number of affected houses. Further, the process is more complex for local builders, and inspectors, who need to work out whether radon protection in new homes is appropriate.Our group has assessed the cost-effectiveness of radon remediation programmes, and has applied this analysis to consider the cost-effectiveness of providing radon protection in both new and existing homes. This includes modelling the potential failure rate of membranes, and whether testing radon levels in new homes is appropriate. The analysis concludes that it is more cost effective to provide targeted radon protection in high radon areas, although this introduces more complexity.The paper also considers the trend in housing to a greater proportion of apartments, the regional variations in types of housing and the decreasing average number of occupants in each dwelling, and concludes that data and methods are now available to respond to the health risks of radon at a local level, in keeping with a general initiative to prioritise responses to health and social welfare issues at a more local level.     

Lung-cancer reduction from smoking cessation and radon remediation: a preliminary cost-analysis in Northamptonshire, UK

Domestic radon levels in parts of the United Kingdom are sufficiently high as to increase the risk of lung-cancer among residents. Public health campaigns in the county of Northamptonshire, a designated radon Affected Area with 6.3% of homes having average radon levels in excess of the UK Action Level of 200 Bq m(-3), have encouraged householders to test for radon and then, if indicated to be necessary, to carry out remediation in their homes. These campaigns have been only partially successful, since to date only 40% of Northamptonshire houses have been tested, and only 15% of those householders finding raised levels have proceeded to remediate. Those who remediate have been shown to have smaller families, to be older, and to include fewer smokers than the average population, suggesting that current strategies to reduce domestic radon exposure are not reaching those most at risk. During 2004-2005, the NHS Stop-Smoking Services in Northamptonshire assisted 2847 smokers to quit to the 4-week stage, the 15% (435) of these 4-week quitters remaining quitters at 1year forming the subjects of a retrospective study considering whether smoking cessation campaigns contribute significantly to radon risk reduction. Quantitative assessment of the risk of lung-cancer among the study population, from knowledge of the individuals' age, gender, and smoking habits, together with the radon levels in their homes, demonstrates that smoking cessation programmes have significant added value in reducing the incidence of lung-cancer in radon Affected Areas, and contribute a substantially greater health benefit at a lower cost than the alternative strategy of reducing radon levels in the smokers' homes, while they remain smokers. Both radon remediation and smoking cessation programmes are very cost effective in Northamptonshire, with smoking cessation being significantly more cost effective, and these are potentially valuable programmes to drive health improvements through promotion of the uptake or environmental management for radon in the home.     

The cost-effectiveness of residential radon remediation programmes: assumptions about benefits stream profiles over time

A recent cost-effectiveness analysis of a residential radon remediation programme considered and highlighted many areas of uncertainty in the parameters chosen for the analysis. One assumption not challenged in the study was the benefits stream profile adopted. There are several different ways of loading the benefits in terms of life years into the cost-effectiveness model and several of these are explored and the results are reported in this study. The benefits profile depends upon the lead-time to cancer manifestation post environmental carcinogen (radon) exposure. The literature reviewed suggests that there are many options for loading benefits to radon-induced lung cancer prevention programmes. In this study, the alternative benefits stream profiles are explored and their implications for the cost-effectiveness ratio are examined. Adopting different benefits stream profiles to the model results in a range of cost-effectiveness ratios from 14912.90 pounds per life year gained to 52416.27 pounds per life year gained. The preferred model is reported where the life years gained are assumed to be equally distributed over the last 15 years of the 40-year time horizon of the analysis (Y25-40) and the corresponding cost-effectiveness ratio is 37,943 pounds per life year gained.     

Health implications of radon distribution in living rooms and bedrooms in U.K. dwellings--a case study in Northamptonshire

Environmental radon exposure of residents of domestic premises in the United Kingdom (UK) and elsewhere in Europe is estimated on the basis of the measured radon concentrations in, and the relative occupancies of, the principal living room and bedroom. While studies on radon concentration variability in the individual units in apartment blocks in various countries have been described, little data has been reported on variability in two-storey single-family dwellings, and the majority of extant studies consolidate living room and bedroom data early in the analysis. To investigate this further, detailed analysis was made of radon concentration data from a set of thirty-four homes situated in areas of Northamptonshire known to exhibit high radon levels. All homes were of typical UK construction of brick/block/stone walls under a pitched tile/slate roof. Approximately 50% of the sample were detached houses, the remainder being semi-detached (duplex) or terraced (row-house). Around 25% of the sample possessed cellars, while 12% were single-storey dwellings (bungalows), reflecting the typical incidence of this type of dwelling in England. In the two-storey homes, all monitored bedrooms were on the upper floor. Distribution of the ratios of bedroom/living room radon concentrations (BR/LR ratio) in individual properties was left-skewed (mean 0.67, median 0.73, range 0.05-1.05) with a tail extending to just above 1.0. The mean is consistent with the outcome of earlier extensive studies in England, while the variability depends principally on the characteristics of the property, and not on seasonal factors. In a small set of homes, the BR/LR ratio was anomalously low, (mean 0.3). BR/LR ratios in single-storey homes clustered around a value of 1.0, indicating that house design, rather than lifestyle, is the dominant factor in determining bedroom radon concentrations. Homes with higher mean annual radon concentrations showed lower BR/LR ratios, supporting our proposal that, in some homes, radon emanation from building materials may comprise a significant component of the overall radon level.     

A study of radon levels in NHS premises in affected areas around the UK

Radon gas contributes a significant fraction of the natural background radiation dose, and in some areas raised levels are found in buildings. both homes and the workplace. Different UK Action Levels apply to homes and the workplace. because of the diurnal variation of radon. This study reviews the results for a number of hospitals throughout England and Wales. and suggests that the likelihood of finding raised radon levels is similar in the workplace and homes in the same area. Radon measurements and consequent remediation of any raised levels are appropriate in all workplaces in radon Affected Areas with over 5% of houses above the UK domestic Action Level of 200 Bq m(-3).     

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.     

Analysis of the individual health benefits accruing from a domestic radon remediation programme

Although radon can be present within buildings at sufficient levels to pose a health risk, levels can be reduced relatively easily. Recent studies on a group of radon-remediated homes, based on assessment of collective population-average risk coefficients, have estimated the benefits and cost effectiveness accruing from remediation and have confirmed that domestic remediation in UK radon Affected Areas would result in significantly reduced cancer risks to the population in those areas. Although the population-average approach used hitherto has applied occupancy and lung-cancer risk factors, these are potentially misleading in assessing discrete populations. The study reported here uses the recently developed European Community Radon Software (ECRS) to quantify individual risks in a sample of householders who remediated their homes following indications that radon levels exceeded the action level. The study proceeds from population-averaged to 'individual risk' evaluation, successfully comparing individual and collective risk assessments, and demonstrates that those who remediate are not representative of the general population. Health benefits accruing from remediation are three times lower than expected, largely because remediators are older, live in smaller households, and smoke less than the population average, leading to the conclusion that the current strategy employed in the UK is failing to target those most at risk.     

Radon mitigation in domestic properties and its health implications--a comparison between during-construction and post-construction radon reduction

Although United Kingdom (UK) Building Regulations applicable to houses constructed since 1992 in Radon Affected Areas address the health issues arising from the presence of radon in domestic properties and specify the installation of radon-mitigation measures during construction, no legislative requirement currently exists for monitoring the effectiveness of such remediation once construction is completed and the houses are occupied. To assess the relative effectiveness of During-Construction radon reduction and Post-Construction remediation, radon concentration data from houses constructed before and after 1992 in Northamptonshire, UK, a designated Radon Affected Area, was analysed. Post-Construction remediation of 73 pre-1992 houses using conventional fan-assisted sump technology proved to be extremely effective, with radon concentrations reduced to the Action Level, or below, in all cases. Of 64 houses constructed since 1992 in a well-defined geographical area, and known to have had radon-barrier membranes installed during construction, 11% exhibited radon concentrations in excess of the Action Level. This compares with the estimated average for all houses in the same area of 17%, suggesting that, in some 60% of the houses surveyed, installation of a membrane has not resulted in reduction of mean annual radon concentrations to below the Action Level. Detailed comparison of the two data sets reveals marked differences in the degree of mitigation achieved by remediation. There is therefore an ongoing need for research to resolve definitively the issue of radon mitigation and to define truly effective anti-radon measures, readily installed in domestic properties at the time of construction. It is therefore recommended that mandatory testing be introduced for all new houses in Radon Affected Areas.     

Indoor radon concentrations

The indoor air of 60 residences in and around a Maryland suburb of Washington, DC, was monitored in a pilot study to determine residential radon concentrations. In each residence, a radon grab sample was acquired in the living room, and, if possible, in the basement. Infiltration rates were determined by tracer gas dilution. To help standardize sampling conditions, each home remained closed up for 8 h prior to sampling and during analysis. Over 60% of the residences sampled showed air infiltration rates below 0.6 air changes per hour. Approximately 55% of all surveyed basements and 30% of all surveyed living areas displayed radon concentrations in excess of 4.0 nCi m⁻³. Assuming an equilibrium factor of 0.5, these radon levels may lead to working levels above the annual guidelines suggested by EPA for florida homes build on land reclaimed from phosphate mining.     

Indoor radon levels in Greek schools

Radon and gamma dose rate measurements were performed in 512 schools in 8 of the 13 regions of Greece. The distribution of radon concentration was well described by a lognormal distribution. Most (86%) of the radon concentrations were between 60 and 250 Bq m⁻³ with a most probable value of 135 Bq m⁻³. The arithmetic and geometric means of the radon concentration are 149 Bq m⁻³ and 126 Bq m⁻³ respectively. The maximum measured radon gas concentration was 958 Bq m⁻³. As expected, no correlation between radon gas concentration and indoor gamma dose rate was observed. However, if only mean values for each region are considered, a linear correlation between radon gas concentration and gamma dose rate is apparent. Despite the fact that the results of radon concentration in schools cannot be applied directly for the estimation of radon concentration in homes, the results of the present survey indicate that it is desirable to perform an extended survey of indoor radon in homes for at least one region in Northern Greece.     

A critical comparison of the cost-effectiveness of domestic radon remediation programmes in three counties of England

Radon remediation programmes in domestic dwellings were carried out in five areas, from three counties of England, and the total costs obtained. A single company, which abided by the Code of Practice of the Radon Council of Great Britain, carried out the remediation. The dose savings from the programmes were calculated and used to estimate the number of lung cancers averted. The data obtained allowed the cost-effectiveness of the remediation programmes in each area to be calculated. The remediation programmes in three areas (Northants 2, 3 and North Oxfordshire) were cost-effective whereas those in two areas (Northants 1 and North Somerset) were not. To be cost-effective, the Northants I and North Somerset areas would need to increase the number of householders that carried out remediation, if they were over the UK Action Level. Health policy makers should concentrate their resources on communities in areas where there is a significant proportion of dwellings above the UK Action Level and where the number of properties being remediated is low.     

Indoor radon levels: Effects of energy-efficiency in homes

The expectation of elevated ²²²Rn levels in modern homes that have low air interchange rates with the outdoor air caused us to survey both solar and conventional homes in northeastern New York State. As a group, homes that are more airtight have three times the ²²²Rn levels of the conventional homes; they have other specific problems that are introduced or exaggerated by modern construction. For example, the highest two levels of radon in the solar homes give doses over 30 years that are known to produce lung cancer in 1% of uranium miners. Summer readings in more than one-half of the cases are different from winter ones by a factor of two or more, so that year-round measurements are necessary for precise dosimetry. The track-etching technique is ideally suited for such measurements. Radon emanation measurements on soils and sand demonstrate a considerable variety of release rates.     

Time-integrating radon gas measurements in domestic premises: comparison of short-, medium- and long-term exposures

To identify the most applicable technology for the short-term assessment of domestic radon levels, comparative assessments of a number of integrating detector types, including track-etch, electret and activated charcoal were undertaken. Thirty-four unremediated dwellings in a high-radon area were monitored using track-etch detectors exposed for one-month and three-month periods. In parallel, one-week measurements were made in the same homes at one-month intervals, using co-located track-etch, charcoal and electret detectors exposed simultaneously, while three of the homes were also monitored by continuous-sampling detectors at hourly intervals over extended periods. Calibration of dose-integrating devices against each other and against continuous-monitoring systems confirmed good responsivity and linearity. Although track-etch, charcoal and electret devices are suitable in principle for one-week measurements, zero-exposure offset and natural radon variability cause many one-week results to be equivocal, necessitating repetition of the measurement. One-week exposures can be reliable indicators in low-radon areas or for new properties, but in high-radon areas, the use of three-month exposures is indicated. This analysis also established confidence limits for short-term measurements.     

Assessment of natural radiation exposure and radon exhalation from building materials in Greece

In controlling the natural radiation exposure for the residents of dwellings, it is necessary to determine the levels of natural radioactivity (external exposure) and radon exhalation rate (internal exposure) from building materials. Using a high-resolution gamma ray spectrometry system, the activity concentration of natural radionuclides was measured. The radon exhalation rate was measured by hermetically closing the sample in a container and following the radon activity growth as a function of time. Three different methods were applied in order to find the most appropriate, i.e. that with the less uncertainty for the less exposure time. Typical building materials were analyzed in order to examine the external and internal exposures. In addition, the total annual effective dose was evaluated for the residents of a typical Greek dwelling.     

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.     

Seasonal changes in radon concentrations in buildings in the region of northeastern Poland

In this study, seasonal observations of radon concentration changes inside buildings carried out in the northeastern region of Poland is presented. One-year measurements of radon concentrations were performed in chosen buildings. The integral method of Cr-39 trace detectors in diffusive chambers was used. Mean values of radon concentrations were determined in monthly, 2-, 3-, 6-month, and annual observations. The fraction of a mean annual concentration of the value obtained in a shorter observation was calculated. Monthly concentration values were from about 0.2 to 14.9 of the annual mean. All buildings revealed seasonal fluctuation of radon concentration. Negative correlation of indoor radon concentration in the buildings and the mean temperature outside was observed in most examined buildings. The lowest coefficient range, determining which part of the annual mean value would be obtained in the 6-month observation, was gained for exposure begun in April or October.     

The effects of geology and the impact of seasonal correction factors on indoor radon levels: a case study approach

Geology has been highlighted by a number of authors as a key factor in high indoor radon levels. In the light of this, this study examines the application of seasonal correction factors to indoor radon concentrations in the UK. This practice is based on an extensive database gathered by the National Radiological Protection Board over the years (small-scale surveys began in 1976 and continued with a larger scale survey in 1988) and reflects well known seasonal variations observed in indoor radon levels. However, due to the complexity of underlying geology (the UK arguably has the world's most complex solid and surficial geology over the shortest distances) and considerable variations in permeability of underlying materials it is clear that there are a significant number of occurrences where the application of a seasonal correction factor may give rise to over-estimated or under-estimated radon levels. Therefore, the practice of applying a seasonal correction should be one that is undertaken with caution, or not at all. This work is based on case studies taken from the Northamptonshire region and comparisons made to other permeable geologies in the UK.     

Indoor radon monitoring in Northern Iran using passive and active measurements

In this work we present the results of a 2-year survey of indoor radon variations in four cities of Lahijan, Ardabil, Sar-Ein and Namin in North and Northwest Iran. We used both passive and active measurements by solid state nuclear track detectors (SSNTDs) with CR-39 polycarbonate and PRASSI Portable radon Gas Surveyor. A total of 1124 samplers in Lahijan, Ardabil, Sar-Ein and Namin were installed. Sampling frequency was seasonal and sampling locations were randomly chosen based on dwelling structures, floors, geological formations, elevation and temperature variation parameters. For quality assurance, 281 active measurements and double sampling were carried out. Based on our results and the results of previous surveys, Ardabil and Lahijan have the second and third highest radon concentration in Iran, respectively (Ramsar is first). The average radon concentration during the year in Lahijan, Ardabil, Sar-Ein and Namin were 163, 240, 160 and 144 Bq/m(3) with medians of 160, 168, 124 and 133 Bq/m(3), respectively. These concentrations give rise to annual effective doses of 3.43 mSv/y for Lahijan and 5.00 mSv/y for Ardabil. The maximum recorded concentration was 2386 Bq/m(3) during winter in Ardabil and the minimum concentration was 55 Bq/m(3) during spring in Lahijan. Relationships between radon concentration and building materials and room ventilation were also studied. The dosimetry calculations showed that these four cities could be categorized as average natural radiation zones. The correlation coefficients relating warm and cold season radon variation data were obtained.