Search Results (116)

Soil-gas observations can retain a source-related response while remaining ambiguous with respect to source amplitude, source depth, transport state, water state, and measurement support. This study develops a reduced one-dimensional source–transport–observation analysis for gas-continuous unsaturated soils. Integral-normalized source kernels, a finite-volume solver, a raw scaled-coordinate Jacobian, common-threshold nuisance projection, and an auxiliary noise-scaled check are combined in a reproducible workflow. At a display tolerance of 0.05, the primary structural convention normalizes parameter columns over the complete 11-row observation universe before extracting observation subsets. Under this convention, a carbon dioxide (CO₂) surface-flux observation retains one projected amplitude direction; within-set normalization reduces that restricted result to zero. The CO₂ profile, ideal-state-constraint set, and full diagnostic set retain ranks of 1/2, 2/3, and 3/4, respectively, under both conventions. The noise-scaled calculation places one projected source response at or above the illustrative one-standard-deviation threshold within a numerical tolerance of 1 × 10⁻¹⁰. A published-data worked example shows why water and carbonate context are required before a gas-phase CO₂ deficit is interpreted as a source decrease. The result is a pre-field screening method, not a site-calibrated inversion. Full article

Radon-222, a decay product of the uranium-238 series, is the principal source of natural ionizing-radiation exposure in most indoor environments and an established cause of lung cancer. In New Mexico, uranium-bearing geology, a legacy of uranium mining and milling, and arid, variably constructed housing create elevated but poorly characterized geogenic radon potential. This evidence-informed narrative review examines radon protection in New Mexico by synthesizing the radiological basis of the hazard (uranium-series sources, radium-226 emanation, and soil–gas transport into buildings) with measurement, monitoring, and mapping evidence relevant to under-resourced regions. We emphasize that representative, high-resolution indoor radon measurements for the state are still lacking. We show that the central challenge is not only geologic potential but the uneven distribution of measurement, testing, and mitigation capacity across housing type, tenure, geography, and jurisdiction, including Tribal lands governed by consent-based data agreements. We evaluate monitoring and outreach interventions by evidence strength and outline a phased, standards-based program (statewide measurement and data systems, high-resolution mapping, school and rental testing, workforce development, and mitigation support) to convert radiological knowledge into measurable, equitable exposure reduction. New Mexico serves as a well-documented representative example; the synthesis is intended to inform other rural, Tribal, and under-resourced jurisdictions. Full article

Residential radon is an invisible radioactive gas produced during the uranium-238 decay series and is an established cause of lung cancer. In Canada, recent national surveillance suggests that about one in five residential buildings may exceed the national radon guidelines, yet household testing remains uncommon. This narrative clinical review translates international and Canadian evidence into practical primary-care and hospital-to-community actions. Evidence was prioritized from carcinogen classifications, World Health Organization guidance, pooled residential case–control analyses, Canadian surveillance and guidance, and the peer-reviewed literature on mechanisms, histology, and risk communication. Radon-222 can enter buildings from soil gas; its short-lived progeny deposits in the respiratory tract and emits high-linear-energy-transfer alpha particles that can damage bronchial epithelial DNA. Because elevated levels cannot be reliably predicted from symptoms, smoking status, house age, or community maps, clinicians should use a simple workflow: ask about prior testing and lower-level occupancy; test with a long-term, approved device in the lowest occupied level; act by interpreting the result, advising mitigation, and directing patients to certified radon professionals when needed; document the exposure assessment, result, advice, referral, and retesting plan; and follow up after mitigation or major building changes. This review clarifies Canadian residential and workplace guidance, contrasts global reference-level approaches, and distinguishes radon prevention from lung cancer screening. No individual patient information or human-subject data are reported. Full article

This study presents a combined analysis of radon and meteorological time series acquired over several years in a building regularly occupied by workers and occasionally by visitors. The building is founded directly on basaltic tuff in an area characterized by elevated radon levels. A multilevel monitoring system with high spatial and temporal resolution was deployed, consisting of 14 low-cost detectors measuring radon and indoor meteorological parameters; an outdoor weather station was employed for environmental and soil monitoring, and a RAD8 instrument was used to identify the main radon entry points. The monitoring system allowed us to characterize, on daily and seasonal timescales, the variability of radon concentration throughout the building and its dependence on meteorological and anthropogenic factors. Cluster analysis combined with a principal component analysis revealed three distinct meteorological regimes (warm, cold, stormy). Indoor radon concentration centroids in the cold and stormy regimes were associated with up to about 3.9 kBq/m³ at RDP2exp, over an order of magnitude above the EU reference level of 300 Bq/m³, while warm, dry conditions yielded significantly lower levels. Horizontal radon diffusion times ranged from 30 to 90 min, and vertical diffusion times ranged from 90 to 180 min across floors. A 24 h exposure risk assessment shows that occupancy during working hours (08:00–18:00) coincides with the daily radon minimum, but baseline concentrations remain above 300 Bq/m³ even during these periods, necessitating mitigation strategies. Full article

Radon is a naturally occurring radioactive gas present in soil, rocks, and water, and is one of the main sources of exposure to natural radiation. It is the second leading cause of lung cancer after smoking. An accurate assessment of indoor radon concentrations is therefore essential for radiation protection and risk management. This study presents a metrological analysis of indoor radon measurements performed using CR-39 nuclear track detectors exposed over varying exposure times. A dataset of 90 measurements was analyzed in accordance with ISO 11929 and ISO 11665-4, with particular attention to the combined use of measurement uncertainty and characteristic limits (decision threshold and detection limit). The results show that characteristic limits allow a statistically consistent discrimination between true radon signals and background fluctuations, while measurement uncertainty provides a quantitative description of the reliability of individual results. The combined interpretation of these quantities enables a more accurate assessment of the validity of the measurements, particularly for values close to the detection limit. In addition, a dimensionless Reliability Ratio (R), defined as the ratio of the measured concentration to the detection limit, is introduced as an operational indicator for evaluating the reliability of individual measurements and comparing results obtained under different exposure times. The proposed framework is demonstrated using real measurement data and highlights the practical role of metrological concepts in supporting decision-making processes in indoor radon risk assessment and mitigation strategies. Full article

Mining activities in the Iberian Pyrite Belt have generated large volumes of legacy wastes that may pose both environmental and radiological concerns, potentially limiting their reuse and valorization. However, integrated assessments combining chemical, mineralogical, and radiological characterization of these materials remain scarce. In this work, representative mining wastes from twelve sites across the Iberian Pyrite Belt were investigated through X-ray fluorescence, X-ray diffraction, scanning electron microscopy, standardized leaching tests, alpha and gamma spectrometry, and radon emanation measurements. The results revealed significant enrichment in potentially toxic elements, particularly Cu, Zn, Pb, and As, with concentrations exceeding local soil background values by up to several orders of magnitude. Leaching tests identified oxidized sulfide-rich residues as the materials with the highest pollutant mobility and greatest acid-generating potential. In contrast, radiological characterization showed that uranium-series, thorium-series radionuclides, and ⁴⁰K activities, together with radiological hazard indices and radon exhalation rates, were generally comparable to those of surrounding natural soils and remained below internationally recommended limits. These findings indicate that chemical contamination represents the main environmental constraint of these wastes, whereas radiological impact is generally low, supporting their case-by-case evaluation for remediation, valorization, and potential exclusion from radiological control. Full article

Radon (222Rn) is a naturally occurring radioactive gas. It is colourless, odourless, and tasteless, produced through the spontaneous decay of uranium in soil and rocks. Among school-aged children, exposure to radon is a major public health concern because, during school hours, learners spend an average of 6–8 h daily inside school buildings, often on the ground floor or in basement classrooms, where radon levels tend to be highest. This study aims to contextualize radon exposure among children in educational settings, with a focus on the associated risk factors. A systematic review of the literature on radon exposure in classrooms among schoolchildren was conducted, analysing associated risk factors and methods of radon measurement. A literature search was performed across reputable databases to ensure compliance with systematic review standards. The quality of the evidence was appraised using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool. A total of 32 studies met the inclusion criteria and were analyzed. Radon levels measured in classrooms exhibit variability based on geographic location. Certain classrooms in Continental Europe and North America exceed the WHO reference limit of 100 Bq/m³, as well as regional thresholds, including the European Union limit of 300 Bq/m³ and the United States Environmental Protection Agency (EPA) limit of 148 Bq/m³. Indoor radon exposure in classrooms is a worldwide concern because children are particularly vulnerable during their formative years. Those attending daycare centers and kindergartens are at greater risk due to their nascent respiratory systems. Full article

Machine learning (ML) models can complement traditional measurement-based approaches by supporting large-scale screening, spatial analysis, and prioritization of buildings for testing of indoor radon, a leading cause of lung cancer among non-smokers. Originating from uranium decay in soil and rock, radon enters homes via foundation cracks and accumulates indoors, influenced by building characteristics, ventilation, urbanization, and geogenic factors. As part of the Zagreb pilot within the “Evidence Driven Indoor Air Quality Improvement” (EDIAQI) project, this is the first ML application for indoor radon analysis in Croatia. This research evaluates residential indoor radon concentrations in Zagreb using ML applied to a dataset of 80 households. Several linear regression and tree-based ensemble methods were tested. The best-performing model (GBR) achieved an R² of 0.99 on the training set and 0.57 on the test set, with an RMSE of 33 Bq/m³ and MAE of 26 Bq/m³. Although predictive performance was moderate and generalization limited, key building characteristics such as construction year, dwelling type, occupancy details, and floor level were identified as relevant variables. The results suggest that machine learning may support radon risk prioritization in urban environments, but cannot replace direct measurements for regulatory purposes. Full article

This work presents the results of an integrated monitoring of soil radon gas and seismic activity at Mt. Etna from August 2023 to May 2025, aimed at enhancing comprehension of magma migration and eruption dynamics. Radon data were collected using a permanent station with an alpha particle probe, aggregated hourly. The INGV-OE network monitored seismic activity at 100 Hz; volcanic tremor was analyzed using Root-Mean-Square (RMS) values from the Serra La Nave station. Earthquakes were located using the Hypoellipse algorithm and a 1D crustal velocity model. A robust correlation was found between radon and RMS anomalies, with the former preceding the latter with increasing probability over time (e.g., 30.1% within 1 day, 46.4% within 3 days). Correlations were also found between radon anomalies and Strombolian activity at the summit craters (e.g., 23.8% within 1 day for the Central Crater), suggesting a potential predictive role for radon. Conversely, correlations with paroxysmal events were weaker in the short term but increased over longer time windows. No clear correlation was found between radon anomalies and seismic strain release, likely due to differing temporal resolutions. These results support the idea that radon plays a role as a short-term precursor in volcanic unrest. Full article

EMFIT, also referred to as EMFi, is a ferroelectret film related to polyvinylidene fluoride (PVDF) sensors. It is an electroactive polymer (EAP) based on a polyolefin structure and consists of three layers of polyester film. Its application in geophysical monitoring has not been reported in the literature. At present, EMFIT is mainly employed in ballistocardiography and medical sleep monitoring, as developed by the manufacturer Emfit Ltd. (Vaajakoski, Finland). Within the multidisciplinary monitoring network of the National Institute for Earth Physics (NIEP), EMFIT is used as a pressure sensor in combination with infrasound transducers and microphones deployed in seismic areas. The primary aim of this study is to evaluate its suitability for detecting seismic noise that precedes earthquakes, generated by rock fracturing associated with crustal deformation. Although similar studies have been reported, they have not involved the use of EMFIT sensors. The novelty of this approach lies in the large surface area and mechanical flexibility of the material. Beyond seismic forecasting, the research also examines whether this type of sensor can contribute to seismic monitoring as a complement to conventional instruments such as accelerometers, seismometers, and microbarometers. Data analysis relies primarily on spectral time-series methods and incorporates measurements from other acoustic sensors (microphones and microbarometers) as well as a weather station. The working hypothesis is the potential correlation between the recorded data and the presence of enhanced noise prior to the detection of seismic waves by standard seismic sensors. The target area for this investigation is Vrancea, specifically the Vrâncioaia seismic station, where multidisciplinary monitoring includes infrasound, radon, thoron, soil temperature, and atmospheric electrical discharges. Preliminary tests suggest that the EMFIT sensor may function as a highly sensitive device, effectively serving as an “ear” for detecting ground noise. Full article

The Shizhuyuan polymetallic deposit in Hunan Province, China, is a world-class ore field rich in tungsten (W), tin (Sn), molybdenum (Mo), and bismuth (Bi), now facing resource depletion due to prolonged exploitation. This study addresses the limitations of traditional geological prediction methods in complex terrain by integrating multi-source datasets—including γ-ray spectrometry, high-precision magnetometry, induced polarization (IP), and soil radon measurements—across 5049 samples. Unsupervised factor analysis was employed to extract five key ore-indicating factors, explaining 82.78% of data variance. Based on these geological features, predictive models including Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGBoost) were constructed and compared. SHAP values were employed to quantify the contribution of each geological feature to the prediction outcomes, thereby transforming the machine learning “black-box models” into an interpretable geological decision-making basis. The results demonstrate that machine learning, particularly when integrated with multi-source data, provides a powerful and interpretable approach for deep mineral prospectivity mapping in concealed terrains. Full article

The Erlian Basin, an important research area for sandstone-type uranium deposit exploration in China, is affected by overburden layers, resulting in indistinct characteristics of uranium anomalies in airborne gamma-ray spectrometry (AGS). To harness the potential of AGS, it is imperative to develop effective verification methods that can identify the spatial relationship between weak uranium anomalies and deep uranium-rich geological bodies. This study presents a comprehensive investigation of geophysical and geochemical measurements conducted in four distinct areas. There is a significant positive correlation between the ground gamma spectrometry equivalent uranium (eU_GGS) content, soil radon concentration (C_Rn), geoelectrochemical uranium (U_GEC), and metal activity state uranium (U_MAS) content directly above and at the edges of uranium-rich geological bodies. When the buried depth of the uranium-rich geological body exceeds 100 m, the eU_GGS content above these deep uranium bodies increases by (0.4–1.2) × 10⁻⁶ g/g compared to background areas, while the C_Rn levels at the edges of these bodies increase by more than 5000 Bq/m³, which is 3–5 times higher than the regional average. Meanwhile, the U_GEC and U_MAS contents show sawtooth-like uranium peak anomalies on their profiles, and their peak-to-background ratio is greater than 5. The verification methods and corresponding interpretation indicators, namely GGS, C_Rn, GEC and MAS measurements, can quickly reveal the spatial relationship and provide a reliable basis for concealed uranium deposit exploration. Full article

This study presents the results of a spatiotemporal analysis of indoor radon concentration dynamics at the Al-Farabi Kazakh National University (Almaty, Republic of Kazakhstan), located near the Almaty tectonic fault. The research is based on a 2.5-year monitoring campaign of radon levels using the RAMON-02A radiometer. The radon activity concentration ranged from 1.29 ± 0.19 to 149 ± 22 Bq/m³. The distribution of radon concentrations was found to follow a lognormal law, with a skewness coefficient of 1.55 and kurtosis of 4.7. The mean values were 28.7 ± 4.2 Bq/m³ (arithmetic mean) and 24.5 ± 3.6 Bq/m³ (geometric mean). Distinct seasonal and monthly variations were observed: the lowest concentrations were recorded during the summer months (August—20.8 ± 3.1 Bq/m³), while the highest were observed in spring and winter (May—34.0 ± 4.9 Bq/m³, December—34.2 ± 4.9 Bq/m³). The springtime increase in radon levels is attributed to thermobaric effects, limited ventilation, and precipitation, which contributes to soil sealing. Autocorrelation analysis revealed diurnal, seasonal, and annual fluctuations, as well as quasi-periodic variations of approximately 150 days, presumably linked to geophysical processes. Correlation analysis indicated a weak positive relationship between radon concentration and air temperature during winter and spring (≈0.2), and a pronounced negative correlation with atmospheric pressure in winter (−0.57). The influence of humidity was found to be minor and seasonally variable. Full article

The naturally occurring radioactive gas radon presents a major public health danger mainly affecting people who spend time in poorly ventilated buildings. The periodic table includes radon as a noble gas which forms through uranium decay processes in soil, rock, and water. The accumulation of radon indoors in sealed or poorly ventilated areas leads to dangerous concentrations that elevate human health risks of lung cancer. The research examines environmental variables affecting radon concentration indoors by studying geothermal installations and their drilling activities, which potentially increase radon emissions. The study was conducted in the basement of the plumbing educational building at the Aristotle University of Thessaloniki to assess the potential impact of geothermal activity on indoor radon levels, as the building is equipped with a geothermal heating system. The key findings based on 150 days of continuous data showed that radon levels peak during the cold days, where the concentration had a mean value of 41.5 Bq/m³ and reached a maximum at about 95 Bq/m³. The reason was first and foremost poor ventilation and pressure difference. The lowest concentrations were on days with increased human activity with measures that had a mean value of 14.8 Bq/m³, which is reduced by about 65%. The results that are presented confirm the hypotheses and the study is making clear that ventilation and human activity are crucial in radon mitigation, especially on geothermal and energy efficient structures. Full article

As a pivotal clean energy source with considerable reserves, geothermal water plays an indispensable role in diminishing reliance on fossil fuels and accomplishing carbon neutrality. This study employed conventional electrical prospecting and radon gas surveys in the Lantian area of Ningdu, aimed at curtailing geothermal development costs by precise targeting of resource locations. The investigations successfully delineated fracture structures within the Lantian region. Distinct anomalies were identified in the electrical profiling along Survey Lines 1, 2, and 4, with the most pronounced features observed on Line 4. Accordingly, characteristic peak anomalies were exhibited by the radon gas measurement profiles S1, S2, and S4 corresponding to Lines 1, 2, and 4, respectively. The synergistic interpretation of resistivity and radon survey data recognized two primary fracture zones: the NE-trending zone F1 and the NEE-trending zone F2. This integrated approach not only ascertained the efficacy of the radon gas measurement, but also lays a robust basis for future geothermal water exploration targeting. Full article