Measurement and analysis of long-term variation of atmospheric Be activity concentrations in Dazaifu (western Japan)

Narazaki, Yukinori*; Sakoda, Akihiro; Akata, Naofumi*; Ito, Hisanori*; Momoshima, Noriyuki*

Journal of Environmental Radioactivity, 284, p.107612_1 - 107612_7, 2025/04

https://doi.org/10.1016/j.jenvrad.2024.107612

Atmospheric Be activity concentration was continuously measured in Dazaifu, western Japan, from 1999 to 2020, and its variation was analyzed. Daily Be data analysis, encompassing an analysis for 22 years, revealed a concentration range of not detected - 18 mBq/m, characterized by substantial monthly variation and smoothed annual variation. An average daily Be activity concentration of 5.0 2.6 mBq/m was considered to be representative at the ground-surface-level in 30-40N. Results from a two-way Analysis of variance (ANOVA) indicated statistical significance in monthly and annual Be variabilities. The monthly variability of Be activity concentration was approximately four times greater than the annual variability. Frequency analysis revealed that the monthly variability comprised major 12-month and minor 6-month periodicities. The substantial decrease in Be activity concentration during summer, a primary driver of monthly variation, was also observed at other locations in Japan, attributed to a stable high-pressure system in the Pacific Ocean that stalled over Japan's southern seas, followed by the inflow of air masses containing low Be activity concentrations. The annual variation was primarily influenced by the 11-year solar activity cycle, which affects the intensity of cosmic rays that produce Be.

Effect of radon inhalation on murine brain proteins; Investigation using proteomic and multivariate analyses

Naoe, Shota*; Tanaka, Ayumi*; Kanzaki, Norie; Takenaka, Reiju*; Sakoda, Akihiro; Miyaji, Takaaki*; Yamaoka, Kiyonori*; Kataoka, Takahiro*

Acta Medica Okayama (Internet), 78(5), p.387 - 399, 2024/10

http://doi.org/10.18926/AMO/67663

Seasonal variations in radon and thoron exhalation rates from solid concrete interior walls observed using in situ measurements

Sakoda, Akihiro; Ishimori, Yuu; Hasan, Md. M.*; Jin, Q.*; Iimoto, Takeshi*

Atmosphere (Internet), 15(6), p.701_1 - 701_12, 2024/06

https://doi.org/10.3390/atmos15060701

Building materials such as brick and concrete are known indoor radon (Rn) and thoron (Rn) sources. Most radon and thoron exhalation studies are based on the laboratory testing of pieces and blocks of such materials. To discuss if laboratory findings can be applied to a real-world environment, we conducted intensive in-situ exhalation tests on two solid concrete interior walls of an apartment in Japan for over a year. Exhalation rates of radon () and thoron () were measured by a measurement system, mainly consisting of an accumulation chamber and dedicated monitors. The indoor air temperature () and absolute humidity () were measured in parallel, and the wall-surface temperature and water content were occasionally measured. All data obtained here were investigated to reveal environmental and material-associated factors affecting exhalation from the concrete walls. There were weak correlations between or and T or at one tested wall, and moderate correlations of and strong correlations of with or at the other wall. Our findings on were consistent with those in a previous laboratory work where a concrete sample was subject to various temperatures, although a corresponding laboratory study of could not be collected. Additionally, moderate or strong correlation between and was observed for both tested walls. The comparison of the measured data and theoretical calculations revealed a new issue on how much impact each process of the emanation and migration within concrete pore spaces has on radon and thoron exhalation. This study provides an insight into parameterizing radon and thoron source inputs in modeling the spatiotemporal dynamics of indoor radon and thoron.

The Report on "study meetings about the ICRP Internal Dosimetry"

Nakajima, Junya; Hirota, Seiko*; Tsuji, Tomoya; Watanabe, Yuki; Sakoda, Akihiro; Kobayashi, Noriko*

Hoken Butsuri (Internet), 58(1), p.13 - 20, 2023/04

https://doi.org/10.5453/jhps.58.13

no abstracts in English

Changes in sulfur metabolism in mouse brains following radon inhalation

Kanzaki, Norie; Sakoda, Akihiro; Kataoka, Takahiro*; Sun, L.*; Tanaka, Hiroshi; Otsu, Iwao*; Yamaoka, Kiyonori*

International Journal of Environmental Research and Public Health, 19(17), p.10750_1 - 10750_14, 2022/09

https://doi.org/10.3390/ijerph191710750

Reactive sulfur species (RSS) involve oxidative stress deeply and contribute anti-inflammatory effect, but no studied have focused on RSS changes after irradiation. In this study, we comprehensively analyzed the metabolites, focusing on RSS in mouse brain following radon inhalation. The ratio of oxidized glutathione to reduced glutathione and proportion of RSS in GSH or cysteine increased by radon inhalation. The sulfur ion might bind to GSH or cysteine chemically under conditions of oxidative stress, even at very low-dose exposure. We performed the overall assessment of high-dimensional data by applying machine learning and showed the specific characteristics of the effects by the exposure conditions. Our results suggested that RSS could produce a biological defense against oxidative stress following radon inhalation.

The Young generation in radiation protection (IRPA YGN) in social media and online learning; "Brave New World" or "Online Nightmare"?

Andresz, S.*; Papp, C.*; Clarijs, T.*; Sakoda, Akihiro; Sez-Muoz, M.*; Qiu, R.*

Journal of Radiological Protection, 42(3), p.031516_1 - 031516_10, 2022/09

https://doi.org/10.1088/1361-6498/ac8a54

While online working seems to become more common since the start of the Covid-19 pandemic, social media has the potential to offer greater interactivity and networking capacities. It seems therefore relevant for the IRPA Young Generation Network to investigate the usage of social media by the young generation in radiation protection trough a survey disseminated online. It was also the opportunity to investigate the early feedbacks about on-line learning. The survey collected 89 answers from 15 countries. The most commonly used social media platforms are first Facebook, then LinkedIn and Twitter, but other social media where reported too. The respondents have a multi-objectives approach on social media, using it for different purposes (chiefly for sharing of news and RP related information/education material) and different audiences (ex. public, professional audience), and are not frenetic users based on the frequencies of publication and consultation and the challenges they see within social media. The survey collected the view of the young generation about their practical experience about learning in virtual setting and its advantages and disadvantages vs. in-person. Most participants expressed mixed-feeling about on-line learning. These results show that the young generation can play a role in supporting the extra and intra-communication of the RP community.

Radon solubility and diffusion in the skin surface layer

Sakoda, Akihiro; Ishida, Tsuyoshi*; Kanzaki, Norie; Tanaka, Hiroshi; Kataoka, Takahiro*; Mitsunobu, Fumihiro*; Yamaoka, Kiyonori*

International Journal of Environmental Research and Public Health, 19(13), p.7761_1 - 7761_12, 2022/07

https://doi.org/10.3390/ijerph19137761

In specific situations such as bathing in a radon spa, where the radon activity concentration in thermal water is far higher than that in air, it has been revealed that radon uptake via skin can occur and should be considered for more precise dose evaluation. The primary aim of the present study was to numerically demonstrate the distribution as well as the degree of diffusion of radon in the skin, with a focus on its surface layers (i.e., stratum corneum). We made a biokinetic model that included diffusion theory at the stratum corneum, and measured radon solubility in the stratum corneum to get a crucial parameter. The implementation of the model suggested that the diffusion coefficient in the stratum corneum was as low as general radon-proof sheets. The depth profile of radon in the skin was found to be that after a 20-minute immersion in water, the radon activity concentration at the top surface skin layer was approximately 1000 times higher than that at the viable skin layer. The information on the position of radon as a radiation source would contribute to special dose evaluation where specific target cell layers are assumed for the skin.

Commencement of discussion toward the next ICRP general recommendations; Report on the symposium on international radiological protection trends and the survey on interesting radiological protection topics among young JHPS members

Sakoda, Akihiro; Tsuji, Tomoya; Hirota, Seiko*; Watanabe, Yuki

Hoken Butsuri (Internet), 57(2), p.108 - 114, 2022/06

https://doi.org/10.5453/jhps.57.108

no abstracts in English

Status of radon exposure in Bangladeshi locations and dwellings

Hasan, Md. M.*; Janik, M.*; Sakoda, Akihiro; Iimoto, Takeshi*

Environmental Monitoring and Assessment, 193(12), p.770_1 - 770_10, 2021/12

https://doi.org/10.1007/s10661-021-09571-4

Potentially higher cancer risk due to exposure from natural background radiation was indicated for Bangladeshi population by estimations based on the countrywide study. Several regions with elevated natural background exhibited higher soil radium and thorium contents than the world average. Being the decay products of these radioactive elements, natural radon isotopes could constitute environmental risk factors for internal radiation exposure to the lungs of people living in these areas. Although lung cancer is one of most prevalent types of cancer in Bangladesh, its status and features are still unclear. To clarify the present status of one of the potential risk factors for lung cancer in the country, this review intends to ascertain the countrywide radon exposure, and its pathways by types of local dwelling and by regions; which would provide an indication of the internal exposures in areas of elevated natural background radiation and radionuclides of soil as well as an understanding of the preliminary contribution of environmental radon on the country's lung cancer prevalence. In this review, countrywide air radon exposures for Bangladeshi dwellings and workplaces are organized from peer-reviewed published papers. Radon has been identified as one of influential sources of radiation dose in Bangladesh with its higher radon exhalation and emanation rate from soil. A novel nationwide depiction of the overall indoor and soil radon levels for Bangladesh has been made through radiation maps. This would be helpful for designing future systematic radon/radiological surveys and research on the country's lung cancer prevalence.

Cosmogenic Be; Particle size distribution and chemical composition of Be-carrying aerosols in the atmosphere in Japan

Narazaki, Yukinori*; Sakoda, Akihiro; Takahashi, Shunta*; Momoshima, Noriyuki*

Journal of Environmental Radioactivity, 237, p.106690_1 - 106690_7, 2021/10

https://doi.org/10.1016/j.jenvrad.2021.106690

The particle size distributions of airborne aerosols with Be were measured using cascade impactors at Dazaifu, a city in western Japan, in 2018 to observe their seasonal variation. Be was found to be attached to aerosols with a particle size of less than 2.1 m; in general, particles sized 0.43-0.65 m had the highest Be activity concentrations. The activity median aerodynamic diameter (AMAD) of Be was in the range of 0.39-0.52 m, which is the size range of particles that can reach human alveoli, and had an annual mean of 0.430.035 m. The activity concentrations of Be were significantly lower in summer, which affected its activity concentrations in the particle size distributions of Be. The particle size distribution of Be-carrying aerosols was also affected by that of the aerosol particles in the atmosphere. Finally, findings suggest that Be was mainly attached to sulfate aerosols (particularly ammonium sulfate aerosols).