Indoor Radon Levels Research Articles

Investigation of the indoor 222Rn and 220Rn levels in the residential environment and estimation of the annual effective radiation dose for ordinary residents.

To evaluate the health risk of radon and its progeny, a large amount of accurate monitoring data is needed according to the theory and practice of health risk assessment. However, the indoor radon levels in different regions in China and worldwide reveal temporal and spatial variations. In addition, the residents living in different areas follow distinct living modes. Therefore, it is recommended and accepted by many researchers to detect the radon level in local areas and subsequently conduct health risk assessments based on local detection data. In this study, 21 bedrooms of households in Weifang city were selected, and the indoor 222Rn and 220Rn levels were detected with RAD7 radon detector in winter, while the annual effective radiation dose was calculated for ordinary residents in Weifang city. Our investigation showed that the 24- and 12-hour average levels of 222Rn were 35.7±15.2 Bq/m3 and 36.2±15.8 Bq/m3, respectively. The 24- and 12-hour average levels of 220Rn were 30.4±12.3 Bq/m3 and 22.4±11.6 Bq/m3, respectively. There were significant differences in the average levels of 222Rn and 220Rn between floors. The estimated annual effective radiation dose received by ordinary residents in Weifang city was 1.7193 mSv, of which 0.9479 mSv originated from 222Rn and its progeny and 0.7714 mSv originated from 220Rn and its progeny, accounting for 55.1% and 44.9%, respectively, of the total dose. Our findings suggest that 220Rn should not be ignored by local residents in Weifang city, and more attention should be paid to 220Rn in future research.

Radon Survey in Bank Buildings of Campania Region According to the Italian Transposition of Euratom 59/2013.

222Rn gas represents the major contributor to human health risk from environmental radiological exposure. In confined spaces radon can accumulate to relatively high levels so that mitigation actions are necessary. The Italian legislation on radiation protection has set a reference value for the activity concentration of radon at 300 Bq/m3. In this study, measurements of the annual radon concentration of 62 bank buildings spread throughout the Campania region (Southern Italy) were carried out. Using devices based on CR-39 solid-state nuclear track detectors, the 222Rn level was assessed in 136 confined spaces (127 at underground floors and 9 at ground floors) frequented by workers and/or the public. The survey parameters considered in the analysis of the results were: floor types, wall cladding materials, number of openings, door/window opening duration for air exchange. Radon levels were found to be between 17 and 680 Bq/m3, with an average value of 130 Bq/m3 and a standard deviation of 120 Bq/m3. About 7% of the results gave a radon activity concentration above 300 Bq/m3. The analysis showed that the floor level and air exchange have the most significant influence. This study highlighted the importance of the assessment of indoor radon levels for work environments in particular, to protect the workers and public from radon-induced health effects.

Evaluation of Indoor Radon and It’s Health Risks Parameters within Azuabie, Trans-Amadi and Nkpogu Towns, in Port Harcourt, Rivers State, Nigeria

Evaluation of indoor radon level and its health risk parameters has been carried out in three communities Azuabie, Trans-Amadi and Nkpogu towns in Port Harcourt, Rivers State, Nigeria. A pocket sized Corentium Arthings digital radon detector meter was used to record the indoor radon concentration levels. The geographical coordinates were recorded using a hand-held geographical positioning system (GPS) for the various sample points. A total of 30 sample points were evaluated, with 10 sample points for each town respectively. The results of the concentration levels showed that for Azuabie (AZ) town, the concentration level varied from 6.660 Bqm-3 to 13.690 Bqm-3 with an average of 10.65±0.95Bqm-3. Nkpogu (NK) town the results of the indoor concentration level ranged from 9.250 Bqm-3 to 18.870 Bqm-3 with an average of 13.32±1.02 Bqm-3, Nkpogu (NK) town, the indoor concentration level ranged from 7.030 Bqm-3 to 20.350 Bqm-3 with an average of 12.25±1.34Bqm-3. The annual absorbed dose for Azuabie, Trans-Amadi and Nkpogu varied as follows, 1.680 mSvy-1 – 3.921 mSvy-1, 2.334 mSvy-1 – 47610 mSvy-1 and 1.774 mSvy-2 – 5.134 mSvy-1 respectively. The annual effect dose rate for the three towns ranged from 0.403 mSvy-1 – 0.941mSvy-1, 0.560 mSvy-1 - 1.143 mSvy-1 and 0.426 mSvy-1 – 1.143mSvy-1. The excess life time cancer risk varied from 1.4117 – 3.294, 1.9607 – 3.999 and 1.4901 – 3.999 respectively. The results of the indoor concentration levels annual and the absorbed dose and the annual effective dose rate are all below the ICRP safe limit. However, the results of the excess life time cancer risk are all higher than the ICRP safe standard limit of 0.029×10-3.

Building design, resident's behavior, and indoor radon in the Commonwealth of Kentucky

This research aims to identify the impact of foundation type on average indoor radon levels in houses in the Commonwealth of Kentucky. It compares the averages of indoor Radon in 4 houses in Warren County, Kentucky, an area classified as zone 1 by the US Environmental Protection Agency. The predicted averages of indoor Radon greater than four pCi/L. The four houses are wood-frame structures; two of them are built on slabs-on-grade, the other two are raised on crawl spaces. A questionnaire was used to gather data about the occupant's behavior towards the indoor air quality in their houses during the test period. A T-test was performed to analyze the radon readings. The data analysis shows a significant difference in indoor Radon between houses of different foundation types. Unlike the previous studies, the houses built on slabs-ongrade show significantly lower averages of indoor Radon than those built on crawlspaces. Also, the results confirm earlier studies regarding the impact of the user's behavior on indoor air quality. Natural ventilation can significantly reduce the averages of indoor Radon. A limitation of this study is that it was carried out in only four houses. More surveys of indoor Radon in buildings with different foundation types are required for results to be generalizable.

A Quantitative Assessment of Indoor Radon Level and Its Annual Effective Dose in Buildings of Gachin Rural District in Hormozgan Province, Iran

Introduction: Measurement of indoor radon concentration and its determining factors is crucial for improving public health and developing proper methods that can reduce indoor radon concentrations. This study aimed to measure the indoor radon concentration and to examine its variations in relation to variables, such as the construction materials, ventilation, and age of buildings. Material and Methods: Indoor radon concentrations were measured using solid-state nuclear track detectors (SSNTDs) during winter. Each detector was mounted 50-90 cm above the surface flooring of bedrooms and living rooms. After three months of exposure, the detectors were collected and transferred to a laboratory. They were then etched in 6.25 N NaOH solution in a bath at a constant temperature of 90°C for 240 minutes. Next, the detectors were washed with distilled water and dried. The alpha particle tracks were counted using an automatic alpha track counting system. Results: The mean radon concentration was 53.20 Bq/m3,and 94% of the samples had a radon concentration 3, which is the action level proposed by the World Health Organization (WHO). The annual effective dose varied from 0.25 mSvy-1 to 3.05 mSvy-1, with a mean dose of 0.91 mSvy-1. The results showed that the type of constructed materials and ventilation influence the indoor radon concentration in winter. Conclusion: The annual effective dose in the study area was below the global average of 1.15 mSvy-1. Therefore, local residents must be informed about the health risks of high radon concentrations and understand the role of improved ventilation in reducing the indoor radon levels.

Study of the possibility of using radon potential maps for identification of areas with high indoor radon concentration

In this study, five different methods for determining the geogenic radon potential are compared in the Mochovce region, Slovakia. Based on these methods, maps of radon potential were made and localities with suspected elevated indoor radon levels were identified. Subsequently, indoor radon concentrations measurements were performed there. Based on the measurements in six municipalities, an approximately linear relationship was found between the values of geogenic radon potential and indoor radon concentrations. These results confirm the usability of radon potential maps as valuable tools for characterizing radon-prone areas.

Estimating population lung cancer risk from radon using a resource efficient stratified population weighted sample survey protocol – Lessons and results from Ireland

A 2018 estimate indicates that there were 226,057 radon-attributable lung cancer deaths in 66 countries that had representative radon surveys. This is a shocking figure, and as it comes from only 66 countries it underestimates the worldwide death toll. Any research that enables countries to conduct representative radon surveys and to understand better the risk to citizens from radon is surely welcome. We hope this paper provides a useful methodology for estimating population risk.The estimation of population weighted average indoor radon levels requires statistically valid sampling methodologies that use a representative sample of occupied homes throughout the country. A literature review indicates that in many population weighted surveys, the sampling methodology may not have been designed to do this. This paper describes a simple, resource efficient methodology which produces statistically valid and reliable estimates based on a small scale sample that is representative of the population distribution. The resource efficient design of this study enables it to be repeated at frequent intervals providing for a longitudinal analysis of the population risk from indoor radon.This survey was conducted in Ireland using 653 measurements and a representative sampling strategy to provide a baseline population weighted radon exposure for future comparisons. This study estimates the average population weighted indoor radon concentration in Ireland to be 97.83 Bq m−3 (95% Confidence Interval 90.69 Bq m−3 to 105.53 Bq m−3), and that there are an estimated 350 lung cancer cases and 255 deaths per year due to radon exposure. The mortality rate of 5.3 per 100,000 due to indoor radon, demonstrates that radon remains one of the highest preventable causes of death in Ireland.

The Anthropogenic Impact on Indoor Radon Concentrations for Secunda, Mpumalanga Province, South Africa.

Secunda is a town built amid the coalfields of the Mpumalanga province of South Africa. Surrounding the town are 11 coal-fired plants (CFPs) contributing around 59% of the country's energy needs. It is also home to Sasol Synfuels, which produces synthetic gas through coal gasification and natural gas reforming. Coal, like most materials found in nature, contains trace elements of the naturally occurring primordial radionuclides 40K, 238U, 232Th, and their decay products. The milling and combustion of coal in a CFP increases the mass concentration of these trace elements, and the residuals end up on ash heaps as fly ash, bottom ash, and boiler slag. A small percentage of fly ash also ends up in the atmosphere. This paper sets out to determine the anthropogenic impact of the industrial activity on indoor radon in the town of Secunda in the Mpumalanga region of South Africa. Measurements were done in 37 homes during July when higher indoor radon levels are expected due to homes typically being closed due to the low temperatures. The average indoor radon concentration was found to be 76.4 Bq m-3. This indicates that the fallout from the industrial activity surrounding Secunda does not enhance the emanation of radon. This may be due to the type of activity or the climate and prevailing winds mitigating its indoor build-up. Measurements during the warmer months and in neighboring towns with different industrial activities are required to confirm the trends established by this research.

Assessment of environmental health risks due to indoor radon levels inside workplaces in Sudan

ABSTRACT The main objective of this study is to assess the environmental health risks due to radon gas accumulation and to compare the concentrations in different kinds of workplaces in Khartoum town, Sudan. However, typical persons spend about one-third of the day at their workplace. For this purpose, a number of 231 measurements were performed in Pharmacies, Schools, Restaurants, Health-care centres, offices, shops, libraries and internet coffee shops by using CR-39 solid-state nuclear track detectors (SSNTD). Results show that the radon concentration values ranged from 16 to 103 Bqm−3, with an average of (54 ± 9) Bqm−3. The mean value of the calculated effective dose was found to be (1.35 ± 0.24) mSvy−1. The relative lung cancer risk due to radon exposure in all workplaces was found to be 1.048%. The results of the study indicated the importance of performing this type of measurement because the exposure of workers can reach high values in some workplaces.

Indoor radon levels in Hungarian kindergartens

Annual average indoor radon activity concentration was studied in 88 Hungarian kindergartens in 76 towns of 10 different counties. Annual average indoor radon activity concentration in the kindergartens was 61 Bq m− 3, maximum was 160 Bq m− 3. In the kindergartens the seasonal variation of radon is not so strong like in dwellings, because of the permanent ventilation and the closed period during the summer break.

Influence of climate and weather on the mitigation of radon exposure in two towns of the Western Cape, South Africa

ABSTRACT Globally, exposure to high levels of radon gas is a known health risk. Granite commonly contains high concentrations of uranium and subsequently high exhalation of radon gas. In the Saldanha Bay area of South Africa, granites dominate the underlying geology as well as the surface characteristics of the area. This implies that elevated levels of radon gas may exist in houses in the area. However, a survey of indoor radon concentrations in the town of Vredenburg in the Saldanha Bay area recorded average indoor radon concentrations well below those recommended as threshold levels by international bodies. The average radon concentrations are also significantly below those recorded in Paarl, a town about 100 km south-east of Vredenburg with a similar underlying geology, but different climatological characteristics. Indoor radon concentrations were measured in 34 homes in Vredenburg, and 62 houses in the west side of Paarl, on or near the granite outcrops. Electret ion chambers (E-PERMTM) from Rad-Elec Inc were used to measure indoor radon in the randomly selected houses in each area. For both surveys, the electrets were deployed for periods of between 5 and 20 days. The Paarl survey was conducted between October 2003 and March 2004, while houses in Vredenburg were surveyed during January and February 2019. In this article, researchers develop a theory to explain the lower than predicted indoor radon concentrations, as well as the difference in results obtained from the Vredenburg and Paarl surveys. They attribute these anomalies to the mitigating effect of the prevailing climatological conditions of the Saldanha Bay area and the generally mild climate experienced at both sites. The research postulates that these conditions can significantly reduce the health hazard associated with elevated indoor radon levels.

Full Analysis of Lung Cancer Mortality/Radon Relationship with Simple Nonlinear Concepts.

We analyze the relationship between the lung cancer mortality and the indoor radon intensity from the viewpoint of nonlinear mathematics. We conclude that their relationship is governed by the proportionality law where the cumulative lung cancer mortality Y is negatively proportional to the cumulative radon intensity X; or specifically, the nonlinear change of nonlinear face value (qYu – qY) is negatively proportional to the nonlinear change of nonlinear face value (X – Xb).The author obtained a set of data from late Professor Cohen on the lung-cancer mortality rate versus indoor radon level collected from 1,597 counties and territory of the USA. We initially presented the data as various primitive elementary graphs; then extended them to the primary graphs, leading graphs, and the proportionality graphs. The article emphasizes the building of a straight-line proportionality relationship for the dose-response data in a log-linear and/or log-log graphs. It demonstrates a straightforward methodology for solving the key upper asymptotes (Yu) for the proportionality equation using the Microsoft Excel via determining the “coefficient of determination”. (Note: q = log, Yu = upper asymptote of Y, Xb = bottom asymptote of X)

Radiometric evaluation of indoor radon levels with influence of building characteristics in residential homes from southwestern Nigeria.

Indoor radon (222Rn) measurements were carried out using solid state nuclear track detectors (SSNTD) in some dwellings from southwestern Nigeria. This was aimed at statistically assessing influence of building characteristics on the measured radon and estimating excess lifetime cancer risks (ELCR). The measured radon concentrations followed lognormal distribution and were significantly influenced by some building properties. The arithmetic mean (1.60mSv) of annual effective doses (AEDs) due to indoor radon was observed to be higher than the world average level (1.15mSv) but less than lower limit (3mSv) of International Commission on Radiological Protection (ICRP). The evaluated excess lifetime cancer risk ranged from 1.5 to 28.1 (MPy)-1 with an average value of 6.3 (MPy)-1, indicating that after exposure to indoor radon for 70years, 6 people in every 1000 are likely to suffer the risk of developing lung cancer. Adequate ventilation systems were recommended for houses with high level of radon to avoid unnecessary exposure to radon. However, the investigated data would form important component of the database required to set up guidelines and policy of controlling radon at home.

INDOOR RADON MEASUREMENTS FOR THE SOUTH AFRICAN WEST COAST PENINSULA.

Granite commonly contains high concentrations of uranium, with consequent high exhalation of radon. The geology of the West Coast peninsula of South Africa is dominated by granite, and a recent article predicted potentially high indoor radon concentrations in this region's two largest towns, Vredenburg and Saldanha. This research aimed to measure indoor radon levels in these towns. Measurements were first done for a minimum of 3d during warmer months, with houses typically being more ventilated. Thirty-four homes in Vredenburg and 27 in Saldanha were measured, and the average indoor radon determined to be 40 and 58Bqm-3, respectively. The measurements were then repeated during the colder months, and an increase in average radon concentration of 173Bqm-3 for Saldanha and 153Bqm-3 for Vredenburg was found. The granite geology and lifestyle of occupants during the colder months seem to contribute towards elevated levels of indoor radon concentrations.

STUDIES OF RADON LEVELS, RADIUM CONCENTRATION, AND ESTIMATED EFFECTIVE DOSE IN DWELLINGS AND SOILS IN GOLD MINING TOWNS IN ABIREM OF EASTERN REGION OF GHANA.

Studies have been carried in 126 dwellings for indoor radon levels and 43 soil samples for radium and radon exhalation rate of Abirem communities in Eastern region of Ghana. The measurements were done using CR-39 and HPGe techniques. Indoor radon and mean concentration ranged from 23.8 to 125.7Bq/m3, 54.7±23.7Bq/m3. Bedroom, kitchen, and sitting varied from 30.8 to 125.7Bq/m3, 23.8-63.9Bq/m3 and 23.8 to 58.4Bq/m3. Strong and weak Pearson correlation were found between radium and radon in soil, radium and indoor radon concentration. Radium concentration and mean were found to be varied from 19.5 to 38.9Bq/kg, 29.0±16.0Bq/kg. The radon exhalation rate and mean in soil were also found to be varied from 21.3 to 112.1 μBq/m2h, 65.1±27.6 μBq/m2h. Indoor radon values and radium concentration in dwellings and soil recorded 8% and 38%, respectively, more than action proposed by WHO and UNSCEAR 2000. The estimated annual effective doses and cancer risk were less than the average values recommended by UNSCEAR and ICRP.

Ambient gamma dose rate as an indicator of geogenic radon potential

Radon is the second cause of lung cancer after smoking, therefore is acknowledged as a major indoor air pollutant. Geogenic radon potential indicates regions where for natural reasons elevated indoor radon levels or elevated probability of their occurrence can be expected. The most common procedure for establishing geogenic radon potential includes measurements of soil permeability and soil gas radon concentrations. These measurements are time-consuming and expensive therefore a limited number of measurements is carried out and their results are extrapolated to the specific area. Our research aimed to analyse the usefulness of ambient gamma dose rate survey to assess radon concentration in the environment and therefore geogenic radon potential. The measurements were carried out on two granite massifs with higher (Karkonosze) and lower (Strzelin) radioactive elements contents. Seasonal variations of atmospheric radon concentrations and ambient gamma dose rates were registered with higher values during warmer and lower during colder seasons. The opposite seasonal variations were observed for soil gas radon concentrations. No distinctive seasonal variations were recorded in results of uranium, thorium and potassium contents in soil measured in situ by the gamma-ray spectrometer. The correlation coefficients were calculated on the base of annual average data. The correlations between ambient gamma dose rate and radon concentration in soil and in the atmosphere were 0.83 and 0.62 respectively, which may suggest that ambient gamma dose rate can be a useful parameter to indicate geogenic radon potential.

Seasonal Variation of Indoor Radon Concentration Levels in Different Premises of a University Building

In the present study, we aimed to determine the changes of indoor radon concentrations depending on various environmental parameters, such as the outdoor temperature, relative humidity, and air pressure, in university building premises of different applications and heights. The environmental parameters and indoor radon concentrations in four different premises were measured each working day over an eight-month period. The results showed that the indoor radon levels strongly depended on the outside temperature and outside relative humidity, whereas the weakest correlations were found between the indoor radon levels and indoor and outdoor air pressures. The obtained indoor radon concentration and environmental condition correlations were different for the different premises of the building. That is, in two premises where the ventilation effect through unintentional air leakage points prevailed in winter, positive correlations between the radon concentration and outside temperature were obtained, reaching the values of 0.94 and 0.92, respectively. In premises with better airtightness, negative correlations (R = −0.96 and R = −0.62) between the radon concentrations and outside temperature were obtained. The results revealed that high quality air isolation in premises could be an important factor for higher indoor radon levels during summer compared to winter.

The 222Rn and 220Rn concentrations in some dwellings of Mandya city and its surroundings, Karnataka, India

The measurement of 222Rn and 220Rn concentrations in air was carried out in 50 dwellings belonging to 20 locations in and around Mandya city, Karnataka. Annual mean values of 222Rn and 220Rn concentrations were found to be 22.4 ± 1.5 and 24.1 ± 1.8 Bq m−3, respectively. The total annual effective dose received by the general public due to radon and thoron was found to be 1.36 ± 0.08 mSv y−1. The doses to different organs and tissues were calculated using the International Commission on Radiological Protection (ICRP) model of the respiratory tract and inter-comparison was made. The flooring, roofing type and age of the buildings were noted and the radon levels with respect to these parameters were analysed and discussed. An attempt was made to predict the indoor radon levels in dwellings using the existing model which was based on the mass balance equation and the results were compared with measured values.

Determination of radon concentration in groundwater of Gadau, Bauchi State, Nigeria and estimation of effective dose

Owing to its proximity to rock and soil, groundwater may contain a non-negligible amount of naturally occurring radioactive materials. If so, the drinking water sourced from deep-bore wells may pose great harm to human health. Acknowledging that water plays a vital role in maintaining a healthy lifestyle, it is important to study the radiological implications of radon gas associated with the intake of groundwater. A total of 10 groundwater samples were analyzed using RAD7 alpha spectrometry (Durridge Co., USA). The measured radon concentration was found to be in the range of 4.92–82.89 (mean 38.3 Bq l−1), which is higher than the US-EPA reference level of 11.1 Bq l−1 or 300 pCi l−1 but within the permissible limit of 100 Bq/m3 set by WHO and EU for indoor radon level (i.e., for inhalation pathway). The values obtained from the studied media were found to be relatively higher than most of the data available in the literature. The mean annual effective dose for ingestion (8.05 μSv y−1) and inhalation (0.10 μSv y−1) was found to be significantly lower than the action level recommended by WHO (0.1 mSv y−1) and ICRP (3–10 mSv y−1), due to 222Rn, 3H and 40K in drinking water. Note that, such a comparison may not reflect the real scenario since our estimated dose is only contributed to by 222Rn. However, the obtained data could serve as a reference for any future radiological study of the waterbody in this region.

Assessing the Impact of Housing Features and Environmental Factors on Home Indoor Radon Concentration Levels on the Navajo Nation.

Uranium is naturally found in the environment as a radioactive metal element with high concentrations in the Southwestern US. In this region is the Navajo Nation, which spans approximately 69,930 square kilometers. A decay product of uranium is radon gas, a lung carcinogen that has no color, odor, or taste. Radon gas may pass from soil into homes; and, indoor accumulation has been associated with geographical location, seasonality, home construction materials, and home ventilation. A home and indoor radon survey was conducted from November 2014 through May 2015, with volunteers who reported residence on the Navajo Nation. Home geolocation, structural characteristics, temperature (°C) during radon testing, and elevation (meters) were recorded. Short-term indoor radon kits were used to measure indoor radon levels. 51 homes were measured for indoor radon levels, with an arithmetic mean concentration of 60.5 Becquerels per cubic meter (Bq/m3) (SD = 42.7). The mean indoor radon concentrations (Bq/m3) by house type were: mobile, 29.0 (SD = 22.9); wood, 58.6 (SD = 36.0); hogan, 74.0 (SD = 0.0); homes constructed of cement and wood, 82.6 (SD = 3.5); and homes constructed of concrete and cement, 105.7 (SD = 55.8). A key observation is that house construction type appears to be associated with the mean home indoor radon concentration. This observation has been published in that the basic structural make-up of the home may affect home ventilation and therefore indoor radon concentration levels.