Radon Progeny Research Articles

Lung cancer and radon: Pooled analysis of uranium miners hired in 1960 or later

BACKGROUND Despite reductions in exposure for workers and the general public, radon remains a leading cause of lung cancer. Prior studies of underground miners depended heavily upon information on deaths among miners employed in the early years of mine operations when exposures were high and tended to be poorly estimated. To strengthen the basis for radiation protection, we report on follow-up of workers employed in later periods of mine operations for whom we have more accurate exposure information and for whom exposures tended to be accrued at intensities that are more comparable to contemporary settings. METHODS We conducted a pooled analysis of cohort studies of lung cancer mortality among 57,873 male uranium miners in Canada, Czech Republic, France, Germany, and the United States, who were first employed in 1960 or later (thereby excluding miners employed during the periods of highest exposure and focusing on miners who tend to have higher quality assessments of radon progeny exposures). We derived estimates of excess relative rate per 100 working level months (ERR/100 WLM) for mortality from lung cancer. RESULTS The analysis included 1.9 million person-years of observation and 1217 deaths due to lung cancer. The relative rate of lung cancer increased in a linear fashion with cumulative exposure to radon progeny (ERR/100 WLM=1.33; 95% CI: 0.89, 1.88). The association was modified by attained age, age at exposure, and annual exposure rate; for attained ages <55 years, the ERR/100 WLM was 8.38 (95% CI: 3.30, 18.99) among miners who were exposed at ages >=35 years and at annual exposure rates <0.5 working levels. This association decreased with older attained ages, younger ages at exposure, and higher exposure rates. CONCLUSIONS Estimates of association between radon progeny exposure and lung cancer mortality among relatively contemporary miners are coherent with estimates used to inform current protection guidelines.

Radon Progeny Adsorption on Facial Masks.

The radioactive noble gas radon and its short-living progeny are inhaled during respiration, depositing their decay energies in the lungs. These progeny are considered responsible for more than 95% of the total effective dose and are, together with radon, classified as carcinogenic for lung cancer. Consequently, filtration of the progeny could reduce the dose to the lungs. In our study, we investigated the filtration properties of FFP2 versus surgical masks (II R) for radon and its decay products. The masks were attached to a measurement device, which enabled determination of the size distribution of radon progeny, ranging from unattached to clustered progeny. In parallel, it measured the radon activity concentration during experiments. By comparing background measurements without mask and experiments with masks, the percentage of retained unattached radon progeny was determined for FFP2 (98.8 ± 0.6%) and II R masks (98.4 ± 0.7%). For clustered progeny, the retained fraction was 85.2 ± 18.1% for FFP2 and 79.5 ± 22.1% for II R masks while radon was not filtered. We can show that masks are effective in filtering radon progeny and thus are capable of reducing the total effective dose to the lungs.

VERTICAL MIXING NEAR THE SEA SURFACE OBSERVED BY SHORT-LIVED NATURAL RADIONUCLIDES ( 214PB AND 214BI).

I performed continuous gamma-ray measurements in seawater to observe the temporal variation of radon progenies ( 214Pb and 214Bi) derived from atmospheric precipitation. Underwater gamma-ray measurements using two NaI(Tl) detectors at different installation depths (1 and 4m) were recorded from July to November 2011 at the marine observation buoy. An increase in the concentration of 214Pb+214Bi in seawater was observed due to precipitation when the wind velocity was<2ms-1. However, this increase was only detected at 1m depth and a downward spread of 214Pb+214Bi was not observed. In contrast, at a wind velocity of>8ms-1, the 214Pb+214Bi concentration ratio at 4m/1m was almost constant (0.6-0.7) for most of the measurement irrespective of precipitation intensity. Assuming one-dimensional diffusion in the water column, the apparent vertical diffusion coefficient estimated from the temporal variation of 214Pb+214Bi concentrations at 4m/1m varied from<10 to 500cm2s-1 depending on the wind velocity.

Assessment of Alpha Doses Received by Spa Workers Due to the Inhalation of 214 Po and 218 Po Radon Progeny.

In Morocco spas are more and more frequented by bathers for massages, body treatments, and aromatherapy and hair services, among others. Alpha-activities due to 222 Rn, 220 Rn and their progeny have been evaluated inside spa room atmospheres by means of a technique based on using two types of solid-state nuclear track detectors. 222 Rn and 220 Rn concentrations ranged between (67 ± 5 and 103 ± 7) Bq m -3 and (5.5 ± 0.4 and 9.8 ± 0.7) Bq m -3 for the studied spa rooms, respectively. The influence of ventilation rate in spa rooms on 222 Rn and 220 Rn concentrations has been studied. Alpha-activities due to the attached and unattached fractions of 214 Po and 218 Po radon progeny have been evaluated in various compartments of the respiratory system of spa working personnel. It has been shown that the majority of 214 Po and 218 Po radon progeny are attached to aerosols inside the considered spa rooms. Alpha-doses to the respiratory tract tissues of spa working personnel due to the energy loss of the emitted alpha-particles were evaluated. It has been shown that alpha-doses to the respiratory system of spa working personnel are influenced by exposure time of workers, mass of respiratory system target tissues, and radon concentration inside the studied spa rooms. The largest value of alpha-dose due to the 214 Po and 218 Po radon progeny from inhalation of air by female workers working 2,080 hours per year in the studied spa rooms was found equal to 5.16 mSv y -1 .

Radon concentration in groundwater of north-eastern Sicily (Italy)

This paper presents analyses of 222Rn activity concentration performed on groundwater samples collected from wells and natural springs in 70 different sites of the crystalline area of north-eastern Sicily (southern Italy), up to now poorly studied. Alpha spectroscopy of the short-lived radon progeny was used to measure the 222Rn activity concentration by means of the Durridge RAD7 + H2O setup. Radon concentrations were derived to be in the range of 1.6–57.5 Bq L-1. The higher values were detected along fluvial valleys and in the crystalline reliefs, whereas aquifers hosted in the alluvial plains show lower radon concentrations. The annual effective dose due to intake of radon by ingestion ranges from 4 to 146.8 μSv y-1. The average value (56.5 μSv y-1) is below the recommended limit of 100 μSv y-1 proposed by the World Health Organization (WHO). In addition, all the measured radon values are lower than the reference level of 100 Bq L-1 set by the Italian legislative decree 28/2016 and by the European Directive 2013/51/Euratom. Therefore, all sampling sites are fully compliant with the legislative requirements in terms of radon levels. Moreover, results show that the radon levels measured in groundwater from north-eastern Sicily are similar to those determined for the adjacent area of southern Calabria, promoting the assumption of a uniform radon signature in the crystalline domain of southern Italy. However, further studies are needed to define better the role of tectonic activity on the content of dissolved radon in groundwater.

MONTE CARLO SIMULATION OF POLONIUM ION COLLECTION IN ELECTROSTATIC FIELD FOR THE PURPOSE OF RADON DETECTOR DEVELOPMENT.

Radon detectors based on an electrostatic collection of polonium and detection of its alpha decay are a popular choice for the measurement of radon activity. Due to the nature of $^{222}$Rn decays, 88% of radon progeny have a positive charge, thus enabling their collection on an electrode. A simulation software focused on the drift and diffusion of ions in an electric field has been developed, providing a tool to study and characterise such detectors. It has been found that one such device achieves only 44% collection efficiency, caused by the loss of a large fraction of the ions before reaching the collection diode. An improvement of the design is therefore proposed, changing the placement of the sensor resulted in an simulated increase of the collection efficiency up to 93%. Preliminary measurements performed using prototypes of these detectors confirm the results of the simulations.

Residential Homes with Extremely High Indoor Radon Concentrations in Southern Lehigh County, Pennsylvania.

A housing development of 87 new homes on approximately 300 acres of former farm land was found to have 19 homes with basement radon-222 ( 222 Rn) concentrations greater than 37,000 Bq m -3 , with the highest recorded result to date being 648,000 +/- 1,031 Bq m -3 , based upon the diffusion barrier charcoal canister result. The US Environmental Protection Agency (EPA) Action Level for 222 Rn is 148 Bq m -3 . This single-family housing development is in the southeast corner of Lehigh County, Pennsylvania, about 58 km northwest of Philadelphia, in a geologic unit known as the Epler Formation. Radon testing in homes in this development began in the fall of 2014 and is now complete. Initial testing consisted of charcoal canisters mailed to homeowners. Subsequent testing in newly built homes consisted of testing prior to occupancy. This testing was quite extensive, with continuous radon monitors, passive radon monitors, and grab sampling for radon gas and progeny in the basement and on the first floor of each home as well as gamma surveys in the basement, on the first and second floors, and outside of each home. All but one of the new houses in this development had passive radon resistant features installed during the construction phase. In all cases, fans were added to the passive systems to make them active systems, which were needed to control these extremely high radon levels. Additional radon mitigation work such as adding additional suction points was also needed in several homes to reduce levels to below EPA guidelines. The unique geology and high 226 Ra soil concentrations in this specific area are the causes of these extremely high radon levels. Radon measurement data both inside these homes and in the outdoor ambient air, as well as 238 U and 222 Ra rock and soil concentrations, are presented.

Nonmalignant respiratory disease mortality in male Colorado Plateau uranium miners, 1960-2016.

To evaluate trends of nonmalignant respiratory disease (NMRD) mortality among US underground uranium miners on the Colorado Plateau, and to estimate the exposure-response association between cumulative radon progeny exposure and NMRD subtype mortality. Standardized mortality ratios (SMRs) and excess relative rates per 100 working level months (excess relative rate[ERR]/100 WLM) were estimated in a cohort of 4021 male underground uranium miners who were followed from 1960 through 2016. We observed elevated SMRs for all NMRD subtypes. Silicosis had the largest SMR (n = 52, SMR = 41.4; 95% confidence interval [CI]: 30.9, 54.3), followed by other pneumoconiosis (n = 49, SMR = 39.6; 95%CI: 29.6, 52.3) and idiopathic pulmonary fibrosis (IPF) (n = 64, SMR = 4.77; 95%CI 3.67, 6.09). SMRs for silicosis increased with duration of employment; SMRs for IPF increased with duration of employment and calendar period. There was a positive association between cumulative radon exposure and silicosis with evidence of modification by smoking (ERR/100 WLM≥10 pack-years = 0.78; 95%CI: 0.05, 24.6 and ERR/100 WLM<10 pack-years = 0.01; 95%CI: -0.03, 0.52), as well as a small positive association between radon and IPF (ERR/100 WLM = 0.06, 95%CI: 0.00, 0.24); these associations were driven by workers with prior employment in hard rock mining. Uranium mining workers had excess NMRD mortality compared with the general population; this excess persisted throughout follow-up. Exposure-response analyses indicated a positive association between radon exposure and IPF and silicosis, but these analyses have limitations due to outcome misclassification and missing information on occupational co-exposures such as silica dust.

Assessment of indoor radon concentration and time-series analysis of gamma dose rate in three thermal spas from Portugal

This work is a follow-up study on the exposure to indoor radon levels in Portuguese thermal spas. The previous research involved 16 thermal spas, where radon measurements in air and thermal mineral water were performed twice a year, from 2012 to 2016. These studies revealed concerning radon concentrations both in air and water. Therefore, a follow-up study on long-term radon measurements was conducted to estimate the year-round average radon exposure. The closer the long-term measurement is to 365 days, the more representative it will be of annual average radon levels. Continuous measurements over 1 year for the indoor radon levels are now presented for three of the 16 previously studied thermal spas, together with a time-series analysis of the gamma dose rates registered within the facilities of these thermal spas (TS). An attempt to identify possible patterns in the variation of gamma dose rates was made. Hourly gamma dose rates were modelled and forecasted using the Box–Jenkins seasonal time series models (SARIMA). The results showed that between December 2018 and November 2019, the indoor radon concentration varied from 202 to 1941 Bq/m3 (TS1), from 52 to 191 Bq/m3 (TS2), and from 937 to 1750 Bq/m3 (TS3). Approximately 60% of the obtained values for radon concentration in the indoor air exceed the reference level of 300 Bq/m3. Gamma dose rates were continuously measured with GAMMA SCOUT® detectors for hourly readings (µSv/h) between 83 and 229 days. On average, the results are similar in all considered locations and range between 0.169 and 0.264 µSv/h, although variations are different in winter and summer. The calculated effective doses ranged between 3.49 and 18.65 mSv/year (TS1), between 1.37 and 2.53 mSv/year (TS2), and between 13.89 and 22.97 mSv/year (TS3). For occupational exposure purposes, workers would be classified as category A in nine locations (out of 20), as the exposure is liable to exceed an effective dose of 6 mSv/year. For the time-series analysis, the obtained models captured the dynamics of the time series data and produced short-term forecasts. Their accuracies have been quantified by minimizing the root mean square error, the mean absolute error due to the actual forecast, and the mean absolute scaled error. The current results corroborate the conclusions of previous research and give continuous data on occupational exposure to radon for three Portuguese thermal spas. For TS1 and TS3, the indoor radon levels are much higher than the reference level. Under this circumstance, mitigation measures must be implemented to reduce the radon levels accordingly with the Euratom Directive 2013/59 and the Decree-Law No. 108/2018. In general, the gamma dose rates were below 1 μSv/h and, therefore, the contribution to the annual effective dose is not significant. Nevertheless, the variation of the gamma dose rates showed a coherent behavior with the radon progeny build up in closed spaces, as when the considered facilities were closed for certain periods. The time series analysis made it possible to fit some models to the gamma dose rate variation, and although the produced models cannot forecast exact gamma dose rates, they can provide valuable information to build sound planning and decision-making strategies in occupational exposure.

A COMPREHENSIVE STUDY ON INDOOR RADON, THORON AND THEIR PROGENY LEVEL IN DIMAPUR DISTRICT OF NAGALAND, INDIA.

Indoor radon (222Rn), thoron (220Rn) and their progeny concentrations were detected in several homes in Dimapur district, Nagaland, utilizing Direct Radon and Thoron progeny sensors based on solid-state Nuclear Track Detectors (Type-2 film) and pinhole type radon-thoron discriminating dosemeters. For three separate seasons, the annual inhalation dose has been determined in 80 residences in the research regions. The residences were chosen to have various types of housing, such as concrete, semi-wood/bamboo and bamboo, with varying levels of ventilation that contribute to indoor 222Rn, 220Rn and their progeny. The inhalation dose in the survey area lies between 0.33 and 3.04mSvy-1 and is within the reference value as suggested by ICRP, 2018.

Study of alpha spectrometry for detection of radon and progeny using gas micro-strip detector

In this paper, simulation of a gas micro-strip detector by using the MCNPX code, the feasibility of alpha spectroscopy for radon and its progeny has been investigated. Initially, for the verification of the code, the range of alpha particles released from 222Rn gas in the air has been obtained in the standard condition, which is consistent with the experimental results. Subsequently, the energy loss per unit path length, range of alpha particles and radon progeny was measured, then the relationship between the range, the energy and the air pressure has been achieved. Finally, the simulation results have been compared with the results of the particle range relationship, pressure and energy, and the radon spectroscopy has been performed with the studied detector. The comparison of the spectrum obtained with the simulated micro-strip detector and the experimental results shows that the introduced micro-strip detector, in addition to the ability to measure radon and daughters, also has the ability to extract the spectrum from it.

Continental thunderstorm ground enhancement observed at an exceptionally low altitude

Abstract. Two long-lasting thunderstorm ground enhancement (TGE) events were registered at the Milešovka meteorological observatory in Czechia (50.55∘ N, 13.93∘ E; 837 m altitude) on 23 April 2018, during linearly organized thunderstorms. Two intervals of increased photon counts were detected by a plastic scintillator, respectively lasting 70 and 25 min and reaching 31 % and 48 % above the background radiation levels. Using numerical simulations, we verified that the observed increases in count rates are consistent with the energy spectrum of previously observed TGEs. We investigated the relevant data from a suite of meteorological instruments, a Ka-band cloud radar, an electric field mill, and a broadband electromagnetic receiver, all placed at the Milešovka observatory, in order to analyse the context in which these unique continental TGEs occurred at an exceptionally low altitude. The onset of the TGEs preceded the onset of precipitation by 10 and 3 min, respectively, for the two events. Both this delayed rain arrival and an energy threshold of 6.5 MeV for registered particles clearly exclude the detection the decay products of the radon progeny washout during the TGE intervals. At the same time, the European lightning detection network EUCLID detected numerous predominantly negative intracloud lightning discharges at distances closer than 5 km from the particle detector, while the occurrence of cloud-to-ground discharges was suppressed. The cloud radar recorded presence of graupel below the melting level, and the composition of hydrometeors suggested good conditions for cloud electrification. The observed variations in the near-surface electric field were unusual, with very brief negative-electric-field excursions reaching −20 kV in a quick succession. At the same time, sub-microsecond unipolar pulses emitted by close corona discharges saturated the broadband magnetic loop antenna. All these measurements indicate that a strong lower positive-charge region was present inside the thundercloud. The bottom thundercloud dipole was probably responsible for acceleration of the seed electrons in the air. These seed electrons might originate in the secondary cosmic ray particles but could also come from a high concentration of radon in the air collected during the propagation of the convective system above the uranium-rich soils before the thunderstorms overpassed the Milešovka observatory.

INTERNAL EXPOSURE FROM INDOOR RADON, THORON AND THEIR PROGENY IN RESIDENCE AROUND HIGH BACKGROUND RADIATION AREA, PHANG NGA PROVINCE, THAILAND.

A passive integrating discriminative radon-thoron monitor (Raduet) and a radon-thoron progeny monitor with a solid-state nuclear tracking detector were used for estimating indoor radon, thoron and their progeny concentrations in residential areas around the old mines of southern Thailand. Exposure to high background radiation levels from natural 238U and 232Th in the tin mine areas or active fault areas may increase the risk of lung cancer in the respiratory system when considering the health effects of the surrounding inhabitants. In this study, radon thoron and their progeny concentrations from inhalation in the study site have been assessed in dose at volunteer houses to confirm radiation effects. The annual effective doses due to inhalation of radon-thoron, radon progeny and thoron progeny using the ICRP latest dose conversion factors were estimated to be 3.0-4.6, 2.5-3.7 and 0.4-1.0mSv, respectively, and as 5.9-9.0mSv in total.

Environmental Gamma Dose Rate Monitoring and Radon Correlations: Evidence and Potential Applications

Gamma emitting radionuclides naturally present in the Earth’s crust and the radon exhaled by soil in the atmosphere with its short-lived progeny are two of the main contributors to the environmental gamma dose rate that typically characterizes an outdoor measurement site. The present work aims to investigate variations in the environmental dose-rate time series originated by different natural phenomena, such as weather and seismic events, which can modify the radon concentration in the air. The data analyzed here were acquired over a five-year period using a Reuter–Stokes high-pressure ionization chamber placed in the ENEA Casaccia Research Center (Rome, Italy), from November 2013 to December 2018. The detector was set to take a single measurement of the equivalent ambient dose H*(10) every 15 min, thereby collecting more than 184,000 values over the five-year period under consideration. The detector’s sensitivity to the short-lived radon progeny was verified in a preparatory study performed by means of simultaneous radon flux measurement on field. Variations induced by meteorological events as well as variations potentially induced by seismic events were investigated by implementing different data analysis techniques. In the latter case, a retrospective preliminary study was conducted, applying the ARFIMA class of models in order to test the method’s potential. The analysis techniques, results and potential applications are presented and discussed in this article.

Lung Cancer and Radon: Pooled Analysis of Uranium Miners Hired in 1960 or Later.

Background:Despite reductions in exposure for workers and the general public, radon remains a leading cause of lung cancer. Prior studies of underground miners depended heavily upon information on deaths among miners employed in the early years of mine operations when exposures were high and tended to be poorly estimated.Objectives:To strengthen the basis for radiation protection, we report on the follow-up of workers employed in the later periods of mine operations for whom we have more accurate exposure information and for whom exposures tended to be accrued at intensities that are more comparable to contemporary settings.Methods:We conducted a pooled analysis of cohort studies of lung cancer mortality among 57,873 male uranium miners in Canada, Czech Republic, France, Germany, and the United States, who were first employed in 1960 or later (thereby excluding miners employed during the periods of highest exposure and focusing on miners who tend to have higher quality assessments of radon progeny exposures). We derived estimates of excess relative rate per 100 working level months (ERR/100 WLM) for mortality from lung cancer.Results:The analysis included person-years of observation and 1,217 deaths due to lung cancer. The relative rate of lung cancer increased in a linear fashion with cumulative exposure to radon progeny (ERR/100 ; 95% CI: 0.89, 1.88). The association was modified by attained age, age at exposure, and annual exposure rate; for attained ages , the ERR/100 WLM was 8.38 (95% CI: 3.30, 18.99) among miners who were exposed at of age and at annual exposure rates of working levels. This association decreased with older attained ages, younger ages at exposure, and higher exposure rates.Discussion:Estimates of association between radon progeny exposure and lung cancer mortality among relatively contemporary miners are coherent with estimates used to inform current protection guidelines. https://doi.org/10.1289/EHP10669

Nuclear structure of radon progeny within the IBM framework

Nuclear structure of radon progeny within the IBM framework

Impact of the Coarse Indoor Non-radioactive Aerosols on the Background Radon Progenies' Compensation of a Continuous Air Monitor.

This paper addresses the problem of false positive alarm when using a continuous air monitor (CAM) in decommissioning sites of nuclear facilities. CAMs are used to measure airborne activity and play an important role in the radiation protection of workers likely to be exposed to radioactive aerosols. Monitors usually sample aerosols on a membrane filter. Radioactive particles sampled are detected through the alpha and beta decays that they emit. These latter ionizing particles are measured online by spectrometry thanks to a Passivated Implanted Planar Silicon detector (PIPS). Alpha and beta decays, in this context, come mainly from the natural radon progeny (218Po, 214Pb, and so on) and, in the case of radioactive contamination, also from artificial radionuclides such as 239Pu or 137Cs. The aim of the CAM is to alert the workers when the artificial airborne activity occurs, always considering the presence of a variable background due to the natural particulate airborne activity. The CAM-specific algorithm considers this background dynamically and continuously, often by using a constant parameter. However, non-radioactive aerosols are also sampled on the membrane filter. These latter make the discrimination more difficult as they lead to the deterioration of the alpha-energy spectrum. In this paper, the effect of coarse non-radioactive aerosols on the CAM response is highlighted with four aerosol size-distributions. The evolution of the background is characterized as a function of the aerosol mass sampled, with the example of a simple algorithm. Thus, in this paper, results show a positive correlation of the background with the aerosol mass sampled by the CAM. In addition, results highlight at least two different evolutionary trends according to the aerosol size distribution. An explanation of these evolutions is given by considering the penetration profile of the natural radioactive aerosols in the granular deposit above the CAM filter. The main consequence of these results is that the background could not be considered as proportional to radon progeny as it is currently used.

Radon Exhalation Rates of Soil Samples from Khon Kaen Province, Thailand

Radon, which can be also detected in water, forms naturally from the decay of uranium and radium found in different amounts in soil and rock. Radon from soil gases is the main cause of health hazards. Radon exhalation escapes from the ground into the air, where radon and radon progeny decays and produces radioactive particles. When inhaled, they can damage the deoxyribonucleic acid and potentially cause lung cancer. Hence, this study measured the radon exhalation rates in soil samples from 26 districts of Khon Kaen Province, Thailand by the active detector method. The closed-loop measurement system in the active detector was made up of the electronic radon detector and a bulk chamber in a 2.8-L volume. The measurement time for each sample was 24 h. Results showed that the radon concentration in soil samples varied from 5.60 to 67.10 Bq m-3 (average: 21.94±4.55 Bq m-3). The radon mass exhalation rates ranged from 7.34 to 17.51 mBq kg-1 h-1 (average: 11.39±3.38 mBq kg-1 h-1) while the radon surface exhalation rates were in the range of 0.29 to 1.31 mBq m-2 h-1 (average: 0.81±0.90 mBq m-2 h-1). The radon surface exhalation rate of the soil samples was below the average worldwide value of 57,600 mBq m-2 h-1 as set by the United Nations Scientific Committee on the Effects of Atomic Radiation. It was concluded that the soil from the province does not pose any radiological health hazard to the general public.

INVESTIGATION OF ENVIRONMENTAL RADIOACTIVITY AT A DECOMMISSIONED URANIUM MINE IN SOUTHERN CHINA.

An environmental radioactivity survey was performed on a uranium mine that has been decommissioned for >10 y. According to the characteristics of this uranium mine, the relevant parameters, such as the surface-absorbed dose rate in air, the radon and radon progeny concentrations in the air, the radon exhalation rate from the soil surface and the concentrations of natural radionuclides in soil and surface water, were measured. The results show that the maximum annual effective doses of residents and employees in the uranium mine caused by radon and radon progenies inhalation were 1.48 and 1.74mSv, respectively, and the maximum annual effective doses of residents and employees caused by gamma-ray external radiation were 1.16 and 1.32mSv, respectively.

Evaluation of indoor radon levels in Staff offices of Umm Al Qura University, Saudi Arabia

Radiation is a natural part of the environment that people interact continuously, and radon is one of the most important sources because of its abundance and mobility. Due to gas form, radon can reach and accumulate in living places easily. Inhalation of radon and its progenies is an important risk factor for health hazards. Accurate measurement of radon levels is quite essential for the dose evaluation of radon exposure in buildings. In this present work, radon concentration was measured indoor 30 office in the College of applied Sciences/Umm Al-Qura University. Radon was measured with a portable Radon counter (Rad 7 detector, Durridge-USA), which was placed on the middle of office at a height of about 0.8 m. 222Rn gas levels were registered in Bq/m3. The measured concentration of radon in the air of office ranged from 14.2 ± 5.68 Bq/m3 to 23.9 ±7.52 Bq/m3 with a mean of 18.96 ± 8.3 Bq/m3, while that of the progeny of radon varied from 0.00164 to 0.00266 WLM Y-1 (average: 0.00211). The mean indoor concentration of radon was considerably less than the lower levels prescribed by EEC 400 Bq/m3, ICRP 200–600 Bq/m3, NRPB 200 Bq/m3, EPA 148 Bq/m3, and WHO 100 Bq/m3. The mean annual effective dose calculated 0.012 mSv y−1, which is less than the UNSCEAR and WHO recommended global lower average dose value of 1 mSv/y. The hazard indices (PAEC, and CPPP) values were lower than the permissibility limit value.