Radon exhalation rate and natural radionuclide content in building materials of high background areas of Ramsar, Iran

Indoor radon measurement in buildings of a university campus in central Iran and estimation of its effective dose and health risk assessment

Indoor radon is a serious health concern and contributes about 10% of deaths from lung cancer in the USA and Europe. In this study, radon and thoron levels of 20 multi-floor buildings on the campus of Isfahan University of Medical Sciences were measured in cold and hot seasons of a year. SARAD- RTM1688 radon and thoron monitor was used for measurement. The annual effective dose of radon exposure was also estimated for residences on the campus. The results showed that radon concentration was below the WHO guideline (100 Bq m- 3) in most of the buildings. The ranges of radon were from 3 ± 10% to 322 ± 15% Bq m- 3 in winter and from below the detectable level to 145 ± 8% Bq m- 3 in summer. Mostly, the radon concentration in the basement or ground floors was higher than upper floors, however, exceptions were observed in some locations. For thoron, no special trends were observed, and in the majority of buildings, its concentration was below the detectable level. However, in a few locations besides radon, thoron was also measured at a high level during both seasons. The average annual effective dose via radon exposure was estimated to be 0.261 ± 0.339 mSv y- 1. The mean excess lung cancer risk (ELCR) was estimated to be 0.10%. It was concluded that indoor air ventilation, buildings' flooring and construction materials, along with the geological structure of the ground could be the factors influencing the radon concentration inside the buildings. Thus, some applicable radon prevention and mitigation techniques were suggested.

Interaction of MS prevalence, radon gas concentration, and patient nutrition: a case-control study

In general, ecological findings indicate a positive correlation between MS and the intake of certain foods. This study aimed to investigate the relationship between radon (Rn) gas concentration and nutrition of patients in food groups with MS. Demographic information, diet, and building characteristics were collected by a questionnaire. Indoors Rn gas was measured using CR-39 detectors. Three models were used in the study of food intake. The interaction analysis between MS prevalence, diet, residential building characteristics, and Rn gas content was performed using SPSS 2020. The total Rn was significantly associated with cooling devices (P = 0.021). Buildings > 20 years had higher Rn concentrations than buildings < 20 years (P = 0.038). Also, no significant relationship was found between Rn-total and MS concentrations, but the total Rn concentration was higher in people homes with MS. Case group used more processed meat than the control (P < 0.001). The case group consumed more butter than the control, which was significant in Model III (P < 0.04). Tomato consumption in the case group was significantly higher than the control (P < 0.03). According to the results there was no interaction between Rn gas concentration in any of the food groups in each cases. However, future studies with larger sample sizes will be needed prospectively.

Is there a relationship between homes' radon gas of MS and non-MS individuals, and the patients' paraclinical magnetic resonance imaging and visually evoked potentials in Yazd-Iran?

Long-term inhalation of radon gas can cause harm to humans and lead to many diseases. One of these diseases is multiple sclerosis (MS), the most common chronic disease of the central nervous system, which alters the brain structure and impedes the rapid transmission of nerve signals throughout the neuron system. Therefore, this study aimed to investigate the relationship of the radon gas concentration in residential homes of MS and non-MS individuals with their results of paraclinical MRI and VEP in Yazd City, Iran. The radon gas concentration was measured in residential homes of 44 people with MS and 100 healthy people. To this end, the questionnaire of radon gas monitoring in residential buildings was administered, and the radon gas concentration was measured by CR-39 detectors. The mean radon concentrations in the homes of MS and non-MS people were 69.51 and 70.83, respectively. A significant positive relationship was found between radon concentration and building's age (P = 0.038). Furthermore, radon concentration had a significant inverse relationship with the building's ventilation (P = 0.053) and cooling systems (P = 0.021). No significant relationship was observed between total radon concentration and MS incidence (P = 0.88). Moreover, no significant correlation was found between radon concentration and location of the plaque in MRI test results of the patients. However, it showed an inverse non-significant correlation with the plaque's number (r = - 0.12, P = 0.42). Further studies in this area are recommended.

Radon and thoron exhalation rate, emanation factor and radioactivity risks of building materials of the Iberian Peninsula

Radon (²²²Rn) and thoron (²²⁰Rn) are radioactive gases emanating from geological materials. Inhalation of these gases is closely related to an increase in the probability of lung cancer if the levels are high. The majority of studies focus on radon, and the thoron is normally ignored because of its short half-life (55.6 s). However, thoron decay products can also cause a significant increase in dose. In buildings with high radon levels, the main mechanism for entry of radon is pressure-driven flow of soil gas through cracks in the floor. Both radon and thoron can also be released from building materials to the indoor atmosphere. In this work, we study the radon and thoron exhalation and emanation properties of an extended variety of common building materials manufactured in the Iberian Peninsula (Portugal and Spain) but exported and used in all countries of the world. Radon and thoron emission from samples collected in the closed chamber was measured by an active method that uses a continuous radon/thoron monitor. The correlations between exhalation rates of these gases and their parent nuclide exhalation (radium/thorium) concentrations were examined. Finally, indoor radon and thoron and the annual effective dose were calculated from radon/thoron concentrations in the closed chamber. Zircon is the material with the highest concentration values of ²²⁶Ra and ²³²Th and the exhalation and emanation rates. Also in the case of zircon and some granites, the annual effective dose was higher than the annual exposure limit for the general public of 1 mSv y⁻¹, recommended by the European regulations.

EXHALATION OF RADON FROM NATURALLY OCCURRING RADIOACTIVE MATERIALS (NORM) IN NIGERIA

Radon-222 mass exhalation rate, EM, and surface exhalation rate, EA, have been determined for some building materials and fertilizers in Nigeria by accumulation method using AlphaGUARD radon monitor. The building materials include granite, cement, tile, white marble, brick, concrete and sand. The mean EM of the building materials varied from 0.06 ± 0.03 for white marble to 0.23 ± 0.15 Bq kg-1 h-1 for brick. The mean EA ranged between 1.06 ± 0.56 Bq kg-1 h-1 and 3.15 ± 1.52 Bq m-2 h-1 for white marble and brick, respectively. Most of the EM and EA of the building materials were higher than those of other countries. For the fertilizers, the EM and EA ranged from 0.13 ± 0.01 to 0.42 ± 0.03 Bq kg-1 h-1 and 2.11 ± 0.56 to 4.81 ± 1.24 Bq m-2 h-1 with mean values of 0.25 ± 0.07 Bq kg-1 h-1 and 3.24 ± 0.93 Bq m-2 h-1, respectively. The radon mass and surface exhalation rates of the fertilizers were higher than those of the building materials.

First indoor radon mapping and assessment excess lifetime cancer risk in Iran

Radon (222Rn) is believed to be the main contributor to lung cancer second to smoking. The first national indoor radon map derived from some scattered regional radon surveys in Iran. The arithmetic mean of indoor radon concentration was calculated to 117.4 ± 97.7 Bq/m3. The mean excess life time cancer risk (ELCR) values were found to be in the range of 0.1%-4.26%, with an overall average value of 1.01%. The mean radon-induced lung cancer risk was 46.8 per million persons. Absence of sufficient indoor radon data showed that national wide monitoring programs should be activated in uncovered areas. Meanwhile, in order to provide further baseline values for radon mapping, we attempted to survey the radon levels inside 50 dwellings of Shabestar County in northwest of Iran. The investigation was also focused on the effects of some buildings related variables. The radon levels recorded varied from 3.92 to 520.12 Bq/m3, with a mean value of 56.19 ± 45.96 Bq/m3. In 9% of dwellings radon concentration exceeded 100 Bq/m3, the limit recommended by the World Health Organization. The average annual effective dose received by the residents of studied area was calculated to be 1.4 mSv. The ELCR was estimated to be 0.54%.

Assessment of radioactivity from selected soil samples from Halfa Aljadida area, Sudan

In this research, the results of radon concentration, surface and mass exhalation rates, radium concentration, effective dose rate and the alpha index have been investigated in a number of 198 soil samples that have been collected from various residential locations of Halfa Aljadida area, Sudan. The can technique, containing CR-39 have been used. From our results, the average value of soil gas radon concentration was found to be 1.96±0.22 kBq·m−3. The average values of surface and mass exhalation rates were 1.73±0.19 Bq·m−2·h−1 and 34.79±3.87 mBq·kg−1·h−1, respectively. The radium concentration average value was 8.06±0.90 Bq·kg−1. While the average value of the effective dose rate was recorded to be 54.69±6.11 mSv·y−1. The average value of alpha index of studied samples was (4.03±0.45)×10−2. From the study, a good positive and linear correlation between radium concentration, surface and mass exhalation rates of soil samples were present. In addition to that, a positive and linear correlation between radium and radon concentrations was found. Finally, a comparison between the results and other findings was conducted and the results imply the fact that the area under consideration is safe as if the health hazard are mentioned.

Indoor radon concentration in Korea residential environments

The purpose of this study is to provide basic data for the evaluation and management of health effects with respect to exposure to radon within residential environments in South Korea. It is part of a case-control study to develop a management plan based on indoor radon exposure levels and assess their impact on health. To investigate the long-term cumulative concentration levels of radon, 599 patients who have respiratory diseases were recruited in South Korea, and alpha track detectors were installed in their residences for a period of 3 months from mid-2015 to late 2016. A survey was then conducted to determine the factors affecting the radon concentration. The radon concentration levels were analyzed in conjunction with the survey results. The results show that the arithmetic mean of the radon concentrations in domestic residences was in the range of 70.8 ± 65.2 Bq/m³. An analysis of covariance (ANCOVA) was performed to identify the environmental factors affecting the radon concentration and contributing to variations in the residential radon concentration based on the height of the residence. The results show that the contribution of the local environmental factor to the variation in radon concentration (p < 0.05) was greater than that of other environmental factors. Although no statistically significant difference was found with regard to the construction year of the building before the control (p > 0.05), the same was found with regard to the construction year after the control (p < 0.05).

ASSESSMENT OF RADIUM ACTIVITY CONCENTRATION AND RADON EXHALATION RATES IN IBERIAN PENINSULA BUILDING MATERIALS

Radium (226Ra) is a natural radioactive element of the uranium decay series, which could also be present in building materials. Radon (222Rn) is continuously produced by the decay of 226Ra and its presence inside buildings can contribute to the increase of the population exposure to ionizing radiation. In this work, the amount of radium activity concentration and radon exhalation rates in several types of building materials that are commonly used in the Iberian Peninsula have been tested. The radium activity concentration was measured by gamma-ray spectrometry, whereas the radon exhalation rates were carried out using a continuous radon monitor (active measuring technique) and a solid state nuclear track detectors (passive measuring technique). The 226Ra mean values range from 5.0 to 123.4 Bq kg-1. As expected, the results show that the radon exhalation rate is higher in granites samples relatively to others building materials analysed. A positive correlation was found between radium activity concentration and radon exhalation rates in both techniques. The emanation fraction and alpha index were also calculated.

The Influence of Internal Wall and Floor Covering Materials and Ventilation Type on Indoor Radon and Thoron Levels in Hospitals of Kermanshah, Iran

BACKGROUND

Building materials and the ventilation rate of a building are two main factors influencing indoor radon and thoron levels (two radioactive gases which have the most important role in human natural radiation exposure within dwellings).

OBJECTIVES

This analytical descriptive study was intended to determine the relationship between indoor radon and thoron concentrations and the building materials used in interior surfaces, as well as between those concentrations and the type of ventilation system (natural or artificial).

MATERIALS AND METHODS

102 measurements of radon and thoron levels were taken from different parts of three hospital buildings in the city of Kermanshah in the west of Iran, using an RTM-1688-2 radon meter. Information on the type of building material and ventilation system in the measurement location was collected and then analyzed using Stata 8 software and multivariate linear regression.

RESULTS

In terms of radon and thoron emissions, travertine and plaster were found to be the most appropriate and inappropriate covering for walls, respectively. Furthermore, granite and travertine were discovered to be inappropriate materials for flooring, while plastic floor covering was found suitable. Natural ventilation performed better for radon, while artificial ventilation worked better for thoron.

CONCLUSIONS

Internal building materials and ventilation type affect indoor radon and thoron concentrations. Therefore, the use of proper materials and adequate ventilation can reduce the potential human exposure to radon and thoron. This is of utmost importance, particularly in buildings with a high density of residents, including hospitals.

On the calibration of a radon exhalation monitor based on the electrostatic collection method and accumulation chamber

The radon exhalation rate can be obtained quickly and easily from the evolution of radon concentration over time in the accumulation chamber. Radon monitoring based on the electrostatic collection method is not interfered with by (220)Rn. In this paper, we propose that the difference between radon and (218)Po concentrations in the measurement cell of this kind of radon exhalation monitor is the main system error, and it changes with time and different effective decay constants. Based on the results of simulation experiments, we propose that the calibration factor obtained from the suitable experiment cannot completely correct the system error, even if it is useful to reduce the measurement error. The better way for reducing measurement error is to use the new measurement model which we have proposed in recent years.

A systematic review of radon investigations related to public exposure in iran

Background

The main sources of radiation exposure of all living organisms including humans are natural. In fact, radon and its decay products are the cause of 50% of the total dose that is derived from natural sources. Because of the significant health hazards of radon gas, its levels are widely monitored throughout the world. Accordingly, considerable researches have also been carried out in Iran.

Objectives

The aim of this research is a systematic review of the most recent studies associated with evaluation of radon gas levels in Iran. The main emphasis of this study was on public exposure to radon gas.

Materials and Methods

The most important route of exposure to such radiation is indoor places. In this investigation measurement of radon in water resources, tap water, indoor places and exhalation of radon from building material, the major sources of indoor radon gas emission, were considered.

Results

Significantly high levels of radon gas were found mostly in water and residenvial buildings.

Conclusions

It conclusion with regard to the study of building materials, granite stone and adobe coverings cannot be recommended for construction purposes.

Natural radionuclide and radiological assessment of building materials in high background radiation areas of Ramsar, Iran

Building materials, collected from different sites in Ramsar, a northern coastal city in Iran, were analyzed for their natural radionuclide contents. The measurements were carried out using a high resolution high purity Germanium (HPGe) gamma-ray spectrometer system. The activity concentration of (226)Ra, (232)Th, and (40)K content varied from below the minimum detection limit up to 86,400 Bqkg(-1), 187 Bqkg(-1), and 1350 Bqkg(-1), respectively. The radiological hazards incurred from the use of these building materials were estimated through various radiation hazard indices. The result of this survey shows that values obtained for some samples are more than the internationally accepted maximum limits and as such, the use of them as a building material pose significant radiation hazard to individuals.