Ambient Radiation Levels Research Articles

Ambient gamma radiation level around Kaveri river basin, Karnataka state, India.

Studies on ambient gamma radiation in indoor and outdoor environment and their effect on human health have created interest among the researchers across the world. The present study represents the results of indoor and outdoor ambient gamma dose rates around the Kaveri river basin from Talakaveri (Madikeri district) to Mekedatu (Ramanagara district) by using portable Environmental Radiation Dosemeter. The annual effective dose in the present study area varies between 0.14mSv.y-1 and 0.58mSv.y-1 with an average value of 0.30mSv.y-1 for indoor radiation. The outdoor annual effective dose ranged between 0.01mSv.y-1 and 0.14mSv.y-1 with an average value of 0.06mSv.y-1. The total annual effective dose varies from 0.17 to 0.72mSv.y-1 with an average value of 0.36mSv.y-1. The calculated values of indoor and outdoor annual effective dose in the study area (are found to be lower than the world average values (1mSv.y-1 and 0.48mSv.y-1).

A Fluorescent Polymer for Facile One‐Step Writing of Polychromic Hidden Information in Flexible Films

AbstractA poly(para)phenylene conjugated polymer is developed to store information via a quick and facile optical writing method. After exposure to UV light, co‐fluorescence (films with two or more written emission colors –, i.e., “double‐on”) and “on‐off” states are written into the flexible polymer films. The hidden information is invisible under ambient lighting and can only be read with an appropriate light source, optical filter, and/or magnifier, thus providing a level of security for information encoded into the films. The physical and chemical mechanisms are discussed responsible for the rapid fluorescence changes that occur under UV exposure and demonstrate microscale multi‐colored artwork and hidden QR codes written into pliable and freestanding films. Depending on the preparation, the written patterns remained easily visible and stable after exposure to water and to ambient levels of UV background radiation.

A study on the ambient electromagnetic radiation level of 5G base stations in typical scenarios

Knowledge of the electromagnetic radiation characteristics of 5G base stations under different circumstances is useful for risk prevention, assessment, and management. This paper selects several typical scenes (Open spaces, building concentration areas, user and building intensive areas) for electromagnetic radiation monitoring, and analyzes the relationship between ambient radiated power density and base station background. The results show that the factors that have significant impacts on the environmental radiation power density of 5G base stations including transmission distance, base station distribution, user density, building reflection superposition and so on. The radiation energy decays rapidly with distance. When the density of the building distribution is too large, the superposition effect caused by the reflected wave is concentrated at the distance of 50-70 meters. When the user density decreases (the superposition effect of reflected waves decreases), the 5G monitoring value follows the direct wave attenuation law and decreases rapidly with the increase of distance. Points with higher measured radiation in the simple access condition also had higher measured radiation in the high-speed download condition. With the popularization of 5G mobile phones and the increase of user density, the resource utilization of a single user will decline to the normal operation state, and the radiation environmental impact will be further reduced.

Study of Natural Background Radiation in Bagmati Province, Nepal

In this research, we explored the influence of natural sources on ambient radiation levels in the surrounding environment. Our investigation involved conducting a comprehensive survey of background radiation across seven districts in the Bagmati province. We utilized a Radalert 100 radiation monitor to measure the background dose rate at 141 different locations. The recorded background ionizing radiation at these sites varied from 0.022 mR/hr to 0.028 mR/hr, averaging at 0.025 mR/hr. The mean dose rate was determined to 2.129 ± 0.172 mSv/y. Subsequently, the obtained dose rates were used to compute the Annual Effective Dose equivalent (AEDE) for the local population, revealing values ranging from 0.240 mSv/yr to 0.294 mSv/yr, with an average of 0.270 mSv/yr. Significantly, these AEDE values exceeded the International Commission for Radiation Protection (ICRP) limit of annual effective dose (1mSv/yr) recommended for the general public. The elevated AEDE levels are likely attributed to the geological characteristics and rock formation in the study area. Despite the higher AEDE, it is important to note that our overall findings suggests no substantial radiological hazard to the public in the study regions.

Investigation of the thermodynamic performance of a direct-expansion solar-assisted heat pump under very cold climatic conditions with and without glazing

This study investigates the long-term thermodynamic performance of a direct-expansion solar-assisted (DX-SAHP) system for hot water production in an average Canadian household. Performance is evaluated using realistic time-varying demand profiles and DX-SAHP with and without glazing under cold climatic conditions. A mathematical model for determining the system's long-term thermodynamic performance based on the first law of thermodynamics and heat transfer fundamentals is developed and thoroughly validated. The solution is implemented in MATLAB®. The CoolProp® database is coupled with MATLAB® and used to determine the working fluid's thermal physical properties. Besides, the thermodynamic performance of the DX-SAHP throughout the year, operating with low global warming potential (GWP) and class A safety refrigerants, was evaluated. Moreover, the influence of solar irradiation and ambient air temperature on the DX-SAHP's thermodynamic performance is studied. Results indicate that the monthly average coefficient of performance (COP) varies between 2.5 and 3.8, while the monthly average energy consumption of the system varies between 170 and 275 kWh. The obtained figures for COP and power consumption demonstrate the high-efficiency potential of the DX-SAHP system, making it an attractive alternative to reduce energy costs and CO2 emissions in residential water heating. In addition, results show that R1233zd gives the highest COPs, followed by R152a, R1234ze, R134a, R1234yf and R32. Besides, the long-term simulation results indicate that the DX-SAHP water heater without glazing has superior thermal performance compared to one with glazing. Also, results show that the COP rises as the ambient temperature or solar radiation level increases.

Unveiling Insights: Harnessing the Power of the Most-Frequent-Value Method for Sensor Data Analysis.

The paper explores the application of Steiner's most-frequent-value (MFV) statistical method in sensor data analysis. The MFV is introduced as a powerful tool to identify the most-common value in a dataset, even when data points are scattered, unlike traditional mode calculations. Furthermore, the paper underscores the MFV method's versatility in estimating environmental gamma background blue (the natural level of gamma radiation present in the environment, typically originating from natural sources such as rocks, soil, and cosmic rays), making it useful in scenarios where traditional statistical methods are challenging. It presents the MFV approach as a reliable technique for characterizing ambient radiation levels around large-scale experiments, such as the DEAP-3600 dark matter detector. Using the MFV alongside passive sensors such as thermoluminescent detectors and employing a bootstrapping approach, this study showcases its effectiveness in evaluating background radiation and its aptness for estimating confidence intervals. In summary, this paper underscores the importance of the MFV and bootstrapping as valuable statistical tools in various scientific fields that involve the analysis of sensor data. These tools help in estimating the most-common values and make data analysis easier, especially in complex situations, where we need to be reasonably confident about our estimated ranges. Our calculations based on MFV statistics and bootstrapping indicate that the ambient radiation level in Cube Hall at SNOLAB is 35.19 μGy for 1342 h of exposure, with an uncertainty range of +3.41 to -3.59μGy, corresponding to a 68.27% confidence level. In the vicinity of the DEAP-3600 water shielding, the ambient radiation level is approximately 34.80 μGy, with an uncertainty range of +3.58 to -3.48μGy, also at a 68.27% confidence level. These findings offer crucial guidance for experimental design at SNOLAB, especially in the context of dark matter research.

Exposure to ionizing radiation and liver histopathology in the tree frogs of Chornobyl (Ukraine)

Ionizing radiation has the potential to damage organic molecules and decrease the health and survival of wildlife. The accident at the Chornobyl Nuclear Plant (Ukraine, 1986) led to the largest release of radioactive material to the environment. Among the different organs of a vertebrate, the liver plays a crucial role in detoxification processes, and has been used as a biomarker to investigate cellular damage in ecotoxicological research. Here, we examined the impact of the exposure to the current levels of ionizing radiation present in the Chornobyl Exclusion Zone on the liver of Eastern tree frogs (Hyla orientalis). We quantified the area of melanomacrophage cells and morphological variables of hepatocytes, two cell types often used to estimate damage caused by pollutants in vertebrates. First, we investigated whether these hepatic parameters were indicative of frog (individual) condition. Then, we analyzed the effect of individual absorbed dose rates and ambient radiation levels on frog livers. Most of the studied parameters were correlated with individual body condition (a good predictor of amphibian fitness and survival). We did not detect marked morphological lesions in the liver of frogs captured in medium-high radiation environments. The area occupied by melanomacrophages and the morphology of hepatocytes did not change across a gradient of radiocontamination covering two orders of magnitude. Once accounting for body condition and sampling locality, the area of melanomacrophages was lower in areas with high radiation levels. Finally, the area occupied by melanomacrophages was not linked to dorsal skin coloration. Our results indicate that current levels of radiation experienced by tree frogs in Chornobyl do not cause histopathological damage in their liver. These results agree with previous physiological work in the species in the Chornobyl area, and encourage further molecular and physiological research to fully disentangle the current impact of the Chornobyl accident on wildlife.

Variation of annual indoor and outdoor gamma dose rate in the lower Himalayan region of Reasi district of Jammu and Kashmir, India

The exposure from natural sources of radiation imparts a major contribution to doses, both due to external and internal exposures that would be received by members of public, and its levels rely upon the lithology, altitude, and building construction materials. The measurement results of ambient indoor and outdoor radiation levels at 28 locations (villages) of Reasi district, Jammu and Kashmir, India, are presented. The ambient radiation levels were measured utilizing a portable gamma survey meter. For the outdoor environment, the minimum and maximum gamma dose rates were 0.09 and 0.29 μSv/h, whereas, at indoors, the minimum and maximum gamma dose rates were 0.08 and 0.22 μSv/h, respectively. Impact of elevation (height above sea level) on radiation levels has been investigated, and it revealed a weak positive relationship with altitude. Effects of lithology on indoor and outdoor gamma dose rates have likewise been investigated. The average annual effective dose value due to ambient radiation levels was well within the world average values.

Assessment of natural radioactivity level before and after a mud-volcano eruption: A study from Piparo mud-volcano, Trinidad and Tobago

The present study was conducted in the Piparo mud-volcano, which is situated in the central part of the island of Trinidad, is geologically connected with the Central Fault Range Zone (CFRZ). This fault zone is a neotectonic (active) strike-slip fault system and an extension of the Andes Mountain chain. This study was aimed at detecting the possible gamma radiation level in Piparo MV after its eruption in September 2019 and finding the change in the ambient radiation level after that eruption. To achieve this aim, gamma radiation data were collected for 6 months (three times at 3 months interval) after this eruption. As a pilot study, gamma radiation measurements were measured with the help of a portable Geiger Muller counter from 32 locations. Radiation levels were nearly 2 times higher than the average background levels in the country indicating Piparo mud-volcano could have controlled the elevated radiation levels in the area. Good correlations were also found between elevated radiation in the northern and western sides of the main crater and presence of auxiliary craters in the same sides. Previous studies reported that the northern side of the crater was more active, and the present study also supported their observation. Good correlation (with coefficient >0.9) indicates that these radioactivity values might be syngenetic. Continuous release and slow reduction of radiation levels (only 13% over 6 months) may indicate a continuous activity in Piparo mud-volcano and may support CRFZ as a creep fault.

Cutaneous malignant melanoma incidence is strongly associated with European depigmented skin type regardless of ambient ultraviolet radiation levels: evidence from Worldwide population-based data.

Current public health advice is that high ultraviolet radiation (UVR) exposure is the primary cause of Malignant Melanoma of skin (CMM), however, despite the use of sun-blocking products incidence of melanoma is increasing. To investigate the UVR influence on CMM incidence worldwide WHO, United Nations, World Bank databases and literature provided 182 country-specific melanoma incidence estimates, daily UVR levels, skin colour (EEL), socioeconomic status (GDP PPP), magnitude of reduced natural selection (Ibs), ageing, urbanization, percentage of European descendants (Eu%), and depigmentation (blonde hair colour), for parametric and non-parametric correlations, multivariate regressions and analyses of variance. Worldwide, UVR levels showed negative correlation with melanoma incidence (“rho” = −0.515, p < 0.001), remaining significant and negative in parametric partial correlation (r = −0.513, p < 0.001) with other variables kept constant. After standardising melanoma incidence for Eu%, melanoma correlation with UVR disappeared completely (“rho” = 0.004, p = 0.967, n = 127). The results question classical views that UVR causes melanoma. No correlation between UVR level and melanoma incidence was present when Eu% (depigmented or light skin type) was kept statistically constant, even after adjusting for other known variables. Countries with lower UVR levels and more Eu% (depigmented or light skin people) have higher melanoma incidence. Critically, this means that individual genetic low skin pigmentation factors predict melanoma risk regardless of UVR exposure levels, and even at low-UVR levels.

Inter-Annual and Seasonal Variability in Ambient Ultraviolet-B Radiation Level at a Tropical Region of Indo-Gangetic Plain

This study evaluated the annual, seasonal, and diurnal variations in the ambient UV-B levels at a tropical region of the Indo-Gangetic plain during 2016 – 2018. Prominent seasonal variations in ambient Ultraviolet-B (UV-B) levels were recorded. Daytime cumulative UV-B varied from 16.75-37.45 (2016), 13.08- 35.89 (2017) and 14.76-34.5 (2018) during summer; from 24.02-3.65 (2016), 18.32-3.11 (2017) and 11.09-2.09 (2018) during winter and 25.56 – 41.17 (2016), 20.1 – 39.21 (2017) and 14.82 – 37.18 (2018) during rainy season. The ambient UV-B level was dependent on numerous meteorological variables (cloud cover, relative humidity, rainfall, and sunshine hours), astronomical factors (Solar Zenith Angle), and pollutants (like tropospheric ozone, sulphur dioxide, nitrogen dioxide, and aerosols). Monthly average UV-B levels positively varied with sunshine hours and PAR and inversely varied with cloud cover. This study suggests that the region is exposed to highly dynamic UV-B levels, which could be a potent threat to plants specially grown during summer-rainy seasons. The study could be further expanded for the entire region using various mathematical tools.

Proteomic Biomarker Analysis of Serum from Japanese Field Mice (Apodemus Speciosus) Collected within the Fukushima Difficult-to-return Zone.

The environmental impact of the Fukushima Daiichi nuclear power plant accident is a source of ongoing concern as there is uncertainty regarding the effects of chronic radiation exposure on local plant and animal life from Fukushima-derived radionuclides. In the current study, changes in proteomic biomarker expression due to chronic environmentally-derived radiation exposures was examined in wild field mice. Serum from 10 wild field mice (Apodemus speciosus) native to the Fukushima difficult-to-return zone and from eight wild field mice native to the Soma area (control) were collected. External dose estimations were completed using measurements of ambient radiation levels and calculating 137Cs concentrations in soil. Internal dose was estimated by counting whole mice using an HPGe detector. Age of the mice was estimated using molar wear. Serum was screened using the aptamer-based SOMAscan proteomic assay technology for changes in expression of 1,310 protein analytes. A subset panel of protein biomarkers that demonstrated significant changes in expression between control and exposed mice was determined and analyzed using Ingenuity Pathway Analysis (IPA). Control animals had a calculated lifetime dose range from 0.001 to 0.007 Gy, and exposed animals had a calculated lifetime dose range from 0.01 to 0.64 Gy. No discernable effect of dose rate was seen as relative dose rate correlated with dose for all samples. Detectable values were obtained for all 1,310 proteins included in the SOMAscan assay. Subset panels of proteins demonstrating significant (p < 0.05) changes in expression with either an upregulated or downregulated 1.5-fold change over control were identified for both the sample cohort inclusive of all exposed samples and the sample cohort restricted to samples from animals receiving "low" dose exposures. These panels of proteins from exposed animals were analyzed using IPA, which highlighted changes in key biological pathways related to injury, respiratory, renal, urological, and gastrointestinal disease, and cancer. Significant changes in expression of proteomic biomarkers were seen in the serum of wild field mice that received environmental exposure to Fukushima-derived radionuclides. Our findings demonstrate novel biomarkers of radiation exposure in wildlife within the Fukushima difficult-to-return zone.

Higher ultraviolet radiation during early life is associated with lower risk of childhood type 1 diabetes among boys

Population-level ecological studies show type 1 diabetes incidence is inversely correlated with ambient ultraviolet radiation (UVR) levels. We conducted a nested case–control study using administrative datasets to test this association at the individual level. Cases (n = 1819) were children born in Western Australia (WA) from 1980–2014, diagnosed with type 1 diabetes at ≤ 16 years. Controls (n = 27,259) were randomly selected from all live births in WA, matched to cases by sex and date of birth. Total ambient erythemal ultraviolet radiation (UVR) doses for each trimester of pregnancy and first year of life were estimated for each individual, using daily NASA satellite data that were date- and geographically-specific. Conditional logistic regression tested the association between UVR dose and case–control status. Type 1 diabetes risk was 42% lower in boys of mothers with third-trimester UVR dose in the highest (compared to the lowest) quartile (p = 0.04). Higher UVR in the first year of life was associated with lower type 1 diabetes risk among boys (p = 0.01). UVR dose was not associated with type 1 diabetes risk in girls. Higher UVR in late pregnancy and early life appear to interact with sex-specific factors to lower type 1 diabetes risk among boys in Western Australia.

Mapping of ambient gamma radiation levels and risk assessment in some parts of Eastern Deccan Plateau, India

ABSTRACT Natural background gamma radiation levels in the indoors and outdoors of certain northern districts of Telangana State, situated on Deccan plateau, were measured with scintillation detector-based survey metre. It was observed that the absorbed gamma dose rates in the indoor and outdoor of the study area were found to vary from 106 nGyh−1 to 322 nGyh−1 with an average of 192 ± 48 nGyh−1, and 102 nGyh−1 to 331 nGyh−1 with an average of 172 ± 50 nGyh−1, respectively. Spatial distribution maps and isodose contours are created using inverse distance weighted technique. The histogram and quantile graphs of the indoor and outdoor natural background gamma radiation levels were observed to follow the structure of symmetrical distribution. The average ratio of indoor to outdoor gamma radiation levels was found to be 1.10. The influence of building materials on the natural background gamma radiation levels was discussed. The annual effective dose was found to vary from 0.20 to 1.89 mSv. The excess life cancer risk was also calculated.

Exploring the Seasonal Drivers of Varicella Zoster Virus Transmission and Reactivation.

Varicella zoster virus (VZV) is a herpesvirus that causes chickenpox and shingles. The biological mechanisms underpinning the multidecadal latency of VZV in the body and subsequent viral reactivation-which occurs in approximately 30% of individuals-are largely unknown. Because chickenpox and shingles are endemic worldwide, understanding the relationship between VZV transmission and reactivation is important for informing disease treatment and control. While chickenpox is a vaccine-preventable childhood disease with a rich legacy of research, shingles is not a notifiable disease in most countries. To date, population-level studies of shingles have had to rely on small-scale hospital or community-level data sets. Here, we examined chickenpox and shingles notifications from Thailand and found strong seasonal incidence in both diseases, with a 3-month lag between peak chickenpox transmission season and peak shingles reactivation. We tested and fitted 14 mathematical models examining the biological drivers of chickenpox and shingles over an 8-year period to estimate rates of VZV transmission, reactivation, and immunity-boosting, wherein reexposure to VZV boosts VZV-specific immunity to reinforce protection against shingles. The models suggested that the seasonal cycles of chickenpox and shingles have different underlying mechanisms, with ambient levels of ultraviolet radiation being correlated with shingles reactivation.

Natural ambient gamma radiation levels, distribution of radionuclides, and evaluation of radiological hazards around Bellary thermal power plant, India

The ambient gamma radiation around the Bellary thermal power plant was measured by Scintillometer of NaI (Tl) detector. The ambient gamma radiation level is mainly dependent upon the activity of primordial radionuclides present in soil and building materials. The activity of natural radionuclides presents in the soil and building materials of some villages around the Bellary thermal power plant is labelled by gamma-ray spectroscopy. The activity of natural radionuclides in soil such as 226Ra, 232Th and 40K varies from 24 to 86.2 Bq·kg−1, 45 to 115 Bq·kg−1 and 145 to 910 Bq·kg−1 with a mean value of 32.5, 79 and 640 Bq·kg−1, respectively. The total measured annual effective dose rate of gamma varies from 0.85 to 1.37 mSv·year−1 and the total calculated annual effective dose rate varies from 0.88 to 1.47 with a mean value of 1.18 mSv·year−1. The measured and calculated values of ambient gamma radiation are very nearer to each other and show positive correlation with a correlation coefficient of 0.44. All the measured radiological indices in soil and building materials are lower than the safe level limit except fly ash bricks, fly ash brick shows a value higher than the safe level limit. The fly ash emitted from the thermal power plant enhances the radiation level in nearby villages. The results are presented and analyzed in this paper.

Determination of the environmental natural radioactivity and mapping of natural background radioactivity of the Gumushane province, Turkey

The aim of the study is to determine the ambient radiation level in Gumushane province. With this aim, the gamma dose ratios absorbed in the air were surveyed by a portable gamma detector. The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in soil samples have been measured by the gamma spectrometric analysis system. The gross alpha and beta activity concentrations in drinking water were also determined by the alpha and beta counting system. By considering the geological structure, the soil samples have been obtained from 62 different spots. In addition, 77 samples of natural and tap water have been collected from different points of the province. The samples were analyzed at the Cekmece Nuclear Research and Training Center in Turkey. Absorbed gamma dose rates in the air were measured in 338 different points in the studied area.

ЭКОЛОГИЯ И КЛИНИЧЕСКИЕ ПОКАЗАТЕЛИ КРОВИ ОБЫКНОВЕННЫХ ШАКАЛОВ (CANIS AUREUS LINNAEUS, 1757), ОБИТАЮЩИХ В ГОРНОДОБЫВАЮЩЕЙ МЕСТНОСТИ КАШЕН МАРТАКЕРТСКОГО РАЙОНА АРЦАХА

In the present work the data received in the territory nearby the Kashen mining centre in the period up to 2018 are discussed. The choice of the locality was not by chance, since, in terms of shelter and food, there have always been concomitant conditions for the stable development of rascals. However, as a result of mining activities, the habitat of these animals has gradually reduced. Our investigations in this sphere can be divided into two stages: Stage 1 –before the start of mining activities in the given terrain, i.e. before 2009, and Stage 2-with the beginning of mining activities, i.e. since 2014. The object of our study were ambient radiation level conditioned changes in blood clinical indexes of ordinary rascals found in Artsakh’s fauna. Researches have been conducted in different seasons across the year. The received data were then compared with the ones obtained before the start of mining activities in the locality. This was done to reveal the consequences of ambient nuclear pollution on blood clinical indexes of animals under study. Rascals’ natural habitat, their preferred territories, the density of population in those territories and other issues related with their mode of living are also discussed in the work.

Plants in the Light of Ionizing Radiation: What Have We Learned From Chernobyl, Fukushima, and Other "Hot" Places?

Perhaps the main factor determining success of space travel will be the ability to control effects of ionizing radiation for humans, but also for other living organisms. Manned space travel will require the cultivation of food plants under conditions of prolonged exposure to ionizing radiation. Although there is a significant literature concerning the effects of acute high dose rate exposures on plant genetics, growth, and development, much less is known concerning the effects of chronic low dose irradiation especially those related to the impacts of the high energy protons and heavy ions that are encountered in the space environment. Here, we make the argument that in situ studies of the effects of radionuclides at nuclear accident sites (e.g., Chernobyl and Fukushima), atomic bomb test sites, and areas of naturally high radiation levels, could provide insights concerning the mechanisms of radiation effects on living systems that cannot be assessed short of conducting research in space, which is not yet feasible for large scale, long term, multigenerational experiments. In this article we review the literature concerning the effects of chronic low-dose rate radiation exposure from studies conducted in Chernobyl, Fukushima, and other regions of the world with high ambient radiation levels (parts of India in particular). In general, mutation rates and other measures of genetic damage are considerably elevated, pollen and seed viability are reduced, growth rates are slower, and the frequency of developmental abnormalities is increased, although there is considerable variation among taxa for these effects. In addition, there are interactions between radiation and other environmental stressors (e.g., temperature, drought, heavy metals) that may play important roles in determining susceptibility to radiation induced stress.

Higher Ultraviolet Radiation During Early Life Reduces Risk of Childhood Type 1 Diabetes Among Boys

Background: Ecological studies show an inverse association between type 1 diabetes incidence and ambient UV radiation (UVR) levels. We used large linked datasets to test ambient UVR during early life against type 1 diabetes risk at the individual level. Methods: We conducted a nested case-control study using linked data from state-wide administrative datasets. Cases (n=1819) were all children born in Western Australia from 1980-2014 with a diagnosis of type 1 diabetes on the Western Australian Children’s Diabetes Database between 0-16 years of age. Controls (n=27 259) were randomly selected from all live births in Western Australia and matched to cases on sex and date of birth. Daily UVR data from NASA satellites, that were date-and location-specific for each individual, were used to estimate total UVR dose for each trimester of pregnancy and the first year of life. Findings: Conditional logistic regression showed that type 1 diabetes risk was 44% lower in boys of mothers with UVR levels in the highest quartile (compared to the lowest quartile) during their third trimester of pregnancy (p=0·04). Higher UVR in the first year of life was also associated with a significantly lower risk of type 1 diabetes in later childhood among boys. Among girls, there was no evidence of associations between total UVR dose and type 1 diabetes risk. Interpretations: Higher UVR in the third trimester and first year of life appears to interact with sex-specific factors to lower type 1 diabetes risk among boys (but not girls) in Western Australia. Funding Statement: This research was supported by an Australian Government Research Training Program Scholarship and a PhD Top-Up scholarship from the Children’s Diabetes Centre, Telethon Kids Institute, Perth WA, Australia. The funding sources had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The corresponding author had access to all the data and all authors agreed on the decision to submit for publication. Declaration of Interests: The authors have no conflicts of interest to disclose. Ethics Approval Statement: Use of these data was approved by the Western Australian Department of Health (2016/05) and the University of Western Australia Human Research Ethics Committee.