Variation Of Indoor Radon Concentration Research Articles

A statistical evaluation of the geogenic controls on indoor radon concentrations and radon risk

ANOVA is used to show that approximately 25% of the total variation of indoor radon concentrations in England and Wales can be explained by the mapped bedrock and superficial geology. The proportion of the total variation explained by geology is higher (up to 37%) in areas where there is strong contrast between the radon potential of sedimentary geological units and lower (14%) where the influence of confounding geological controls, such as uranium mineralisation, cut across mapped geological boundaries. When indoor radon measurements are grouped by geology and 1-km squares of the national grid, the cumulative percentage of the variation between and within mapped geological units is shown to be 34–40%. The proportion of the variation that can be attributed to mapped geological units increases with the level of detail of the digital geological data. This study confirms the importance of radon maps that show the variation of indoor radon concentrations both between and within mapped geological boundaries.

Analysis of seasonal variation of indoor radon concentration in Tehri Garhwal, Northern India

The seasonal variation analysis of indoor radon has been carried out in the hilly region of Tehri Garhwal, Northern India by using LR-115 Type II, plastic track detector. In the analysis the winter/summer ratio radon values were found to vary from 0.63 to 1.64 and 1.02 to 1.22 for cemented houses and mud houses, respectively. Over all the average value of winter/summer ratio was found maximum in both cemented and mud houses respectively.

Annual average and seasonal variations of indoor radon concentrations in Piedmont (Italy) using three different detection techniques

One year survey of indoor radon concentrations was carried out in public buildings, schools and dwellings of the neighbouring small towns of Nichelino and Castagnole Piemonte, nearby Turin, Piedmont (Italy), as part of a long term assessment of local radon levels. Three kinds of detectors have been deployed for nearly 500 exposures: electrects, solid state nuclear track detectors and a continuous on-line monitor. A log-normal model was applied to estimate the fraction of dwellings with high radon concentration. The resulting effective dose-equivalent for the inhabitants of Castagnole Piemonte and Nichelino, calculated from the geometric means, is 0.7 and 0.5 mSv y - 1 , respectively.

Using the Real-time Radon-222 Profile to Quantify the Specific Radon Production Rate in an Air-conditioned Building

The real-time indoor and outdoor radon-222 profiles on the fourth floor of a university library were measured through five consecutive days, with the Heating, Ventilating and Air Conditioning (HVAC) system operating on part load. The premises were served by a main air-handling unit (AHU-1) and a subordinate unit (AHU-2) of the HVAC system, but AHU-2 was shut down for maintenance. It required full operation of AHU-1 for 1.7h to reduce the radon concentration from the overnight peak down to the recommended action level (200Bq·m-3). Clear characteristics of indoor radon profiles were observed, with the diurnal variations of indoor radon concentrations strongly coupled to the operation schedule of AHU-1. The specific radon production (value-Φ) of the site could be quantified from the characteristic profiles. This can be used to investigate the radon emission rate of a site, as well as to simulate the indoor radon concentrations at different ventilation rates. The value-Φ was 21.0Bqh-1·m-3, with a standard deviation of 0.6Bqh-1·m-3. Furthermore, it was found that a morning purge, by the fresh air intake fan operating for 2h before library opening hours, could not effectively remove the overnight accumulation of the pollutant.

Problems in radon measurements in context of epidemiological studies

Epidemiological case control study is considered to be primary instrument to investigate the relationship between population indoor radon exposure and risk of lung cancer. A number of such studies had been completed in last 15 years and others are running now. Considering indoor radon and progeny some specific efforts should be undertaken to assess the exposure. While the lungs exposure after inhalation arises mainly due to radon progeny, in the case of the radon gas measurements application the researchers have to address the disequilibrium between radon and radon progeny. It is widely accepted by researchers and approved by ICRP that worldwide average value of equilibrium factor is 0.4 though real equilibrium factor value can deviate significantly from average. Temporal variation of indoor radon concentration complicates the evaluation of exposure as well. Three types of variation can be emphasized: diurnal, seasonal and long time. Experimental and modeling investigation of radon entry shown that pattern of indoor radon temporal variation firmly depends on relationship between entry rates of primary radon sources (diffusive and advective) and influencing factors are construction characteristics, climatic condition and life style. To find appropriate parameters describing radon disequilibrium and temporal variation it is necessary to perform special investigation in the representative sample of houses.

210Po implanted in glass surfaces by long term exposure to indoor radon.

Recent epidemiologic investigations of the relationship between residential radon gas exposure and lung cancer relied on contemporary radon gas measurements to estimate past radon gas exposures. Significant uncertainties in these exposure estimates can arise from year-to-year variation of indoor radon concentrations and subject mobility. Surface implanted 210Po has shown potential for improving retrospective radon gas exposure estimates. However, in previous studies, the ability of implanted 210Po activity to reconstruct cumulative radon gas exposure was not tested because glass was not available from homes with known radon-gas concentration histories. In this study, we tested the validity of the retrospective radon gas reconstruction using implanted 210Po surface activity by measuring glass surfaces from homes whose annual-average radon gas concentrations had been measured almost every year during two decades. Regression analysis showed a higher correlation between measured surface activity and cumulative radon gas exposure in these homes (R2>0.8) than was observed in homes where only contemporary radon gas measurements were available. The regression slope (0.57 ky m(-1)) was consistent with our earlier retrospective results. Surface activity measurements were as reliable for retrospective radon gas exposure reconstruction as yearlong gas measurements. Both methods produced estimates that were within 25% of the long-term average radon gas concentrations in a home. Surface measurements can be used for home screening tests because they can provide rapid, reliable estimates of past radon gas concentrations. Implanted 210Po measurements are also useful in retrospective epidemiologic studies that include participants who may have been exposed to highly variable radon concentrations in previously occupied or structurally modified homes.

A Study of Diurnai Variation of Indoor Radon Concentrations.

A Study of Diurnai Variation of Indoor Radon Concentrations.

Diurnal variation of indoor radon concentration in Malaysia

This paper reports time continuous measurement of radon in a sub-basement room in order to show the hourly diurnal variation in indoor radon concentration. The variation in temperature and humidity was also recorded.

Bayesian prediction of mean indoor radon concentrations for Minnesota counties.

Past efforts to identify areas with higher than average indoor radon concentrations by examining the statistical relationship between local mean concentrations and physical parameters such as the soil radium concentration have been hampered by the variation in local means caused by the small number of homes monitored in most areas. In this paper, indoor radon data from a survey in Minnesota are analyzed to minimize the effect of finite sample size within counties, to determine the true county-to-county variation of indoor radon concentrations in the state, and to find the extent to which this variation is explained by the variation in surficial radium concentration among counties. The analysis uses hierarchical modeling, in which some parameters of interest (such as county geometric mean radon concentrations) are assumed to be drawn from a single population, for which the distributional parameters are estimated from the data. Extensions of this technique, known as random effects regression and mixed effects regression, are used to determine the relationship between predictive variables and indoor radon concentrations; the results are used to refine the predictions of each county's radon levels, resulting in a great decrease in uncertainty. The true county-to-county variation of geometric mean radon levels is found to be substantially less than the county-to-county variation of the observed geometric means, much of which is due to the small sample size in each county. The variation in the logarithm of surficial radium content is shown to explain approximately 80% of the variation of the logarithm of geometric mean radon concentration among counties. The influences of housing and measurement factors, such as whether the monitored home has a basement and whether the measurement was made in a basement, are also discussed. The statistical method can be used to predict mean radon concentrations, or applied to other geographically distributed environmental parameters.

Seasonal Variations of Radon Concentrations in Single-Family Houses with Different Sub-Structures

Seasonal variations of indoor radon concentrations have been studied in 70 single-family houses selected according to the type of sub-structure and the type of soil underneath the house. Five categories of sub-structure were included - slab-on-grade, crawl space, basement, and combinations of basement with slab-on-grade or crawl space. Half of the houses are located on clayey till and the other half on glaciofluvial gravel. In each house radon was measured in a living room and a bedroom, in the basement if present, and in the crawl space if present and accessible. The measurements were made with track detectors on a quarterly basis throughout a year. For living rooms and bedrooms the seasonal variations range from being highly significant for the slab-on-grade houses to being insignificant for the crawl space houses. For basements and crawl spaces the geometric mean radon concentrations do not show significant seasonal variations.

福岡・鹿児島における屋内ラドン濃度調査

It is now well established that radon and its daughter products account for nearly half of the average population exposure to ionizing radiations and that radon is the greatest single source of natural radiation to the population. Radon and its daughters are alpha-emitters, which are more biologically damaging than beta- and gamma-radiations. A nationwide survey of radon concentration was conducted by the National Institute of Radiological Sciences in order to estimate the contribution of radon and its daughters to the population dose in Japan. Authors surveyed indoor radon concentrations in Fukuoka and Kagoshima prefectures as part of this project. A passive type radon dosimeter, in which a sheet of polycarbonate film as the alpha-ray detector was mounted, was used to measure indoor radon concentrations. The resulting distribution of the average annual indoor radon concentrations in both prefectures can be characterized by an arithmetic mean of 24.4 Bq/m3 and a standard deviation of 13.1 Bq/m3, by a geometric mean of 22.2 Bq/m3, and by a median of 20.7 Bq/m3. The geometric means of the distributions for Fukuoka and Kagoshima were 25.4, and 18.4 Bq/m3, respectively. Radon concentrations were also generally high in winter and low in summer. Regarding the analysis of correlations between the concentrations and construction materials, radon concentrations were generally high in Japanese houses with earthen walls and in concrete structures. These results showed that seasons, the type of building materials, and regional differences were significant factors in the variation of indoor radon concentration.