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Povzetek: Laboratory and field assessments of low-cost sensors (LCS) are essential for ensuring the accuracy of PM2.5 measurements collected by citizens in air quality campaigns. Evaluation of Sensirion SPS30 (LCS SPS30) in controlled laboratory setting showed a coefficient of determination (R2) ranging from 0.81–0.99 and a root mean square error (RMSE) from 0.81–61.72 μg m−3, at average concentration of 21.5 μg m−3. In contrast, co-location assessment at an average concentration of 9 μg m−3 resulted in R2 of 0.5 and a RMSE of 6.82 μg m−3. The results demonstrated that the sensor met micro-environmental monitoring standards (accuracy < 25%) and United States Environmental Protection Agency's performance criteria (RMSE ≤ 7 μg m−3, R2 > 0.7) only at relative humidity (RH) levels below 60%, emphasising its strong sensitivity to RH and the need for RH-dependent data corrections. The observed underestimation or overestimation of PM2.5 readings was primarily attributed to variations in particle composition and concentration. Despite accuracy variations, LCSs can effectively capture spatiotemporal urban air quality patterns and identify pollution hotspots in community monitoring, particularly in low-pollution environments. In a citizen-led PM2.5 monitoring campaign in Maribor, Slovenia, the lowest concentrations were recorded at 15:00 (2.9 μg m−3), while the highest occurred during the morning rush-hour (4.8 μg m−3), likely attributed to the planetary boundary layer’s impact on atmospheric particulate dispersion. Spatial analysis revealed that hotspots clustered near intersections, where vehicle waiting time is the longest.
Ključne besede: particulate matter, low-cost sensor, Sensirion SPS30, citizen science, calibration
Objavljeno v DiRROS: 18.09.2025; Ogledov: 286; Prenosov: 191
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Povzetek: As lithium-ion technology's exhibits inherent issues with safety due to thermal runaway, a sustainable and cheaper alternative has been proposed in this work: the rechargeable alkaline battery chemistry. However, so far, the postulated safety of the new battery chemistry has not been demonstrated adequately. Therefore, a safety study is being carried out for rechargeable alkaline battery cells. This Short Communication paper is the first report on the thermal safety of Zn-MnO₂ CR2032 rechargeable alkaline battery coin cells. 100% charged coin cells were tested under thermal abuse conditions in a gravity-convection furnace to quantify the temperature at which the cell would go into thermal runaway. Morphological characterisation of pristine and tested cells was performed via laboratory-based X-ray computed microtomography. The onset temperature to thermal runaway for the rechargeable alkaline battery cells was found to be in the range of 290-380 °C, much higher than that reported in the literature for lithium-ion cells (150-200 °C) of similar capacity and geometry. These results emphasise that rechargeable alkaline battery technology has improved thermal stability compared to lithium-ion technology. Lastly, morphological analyses highlighted the variations of cell geometry brought about by thermal testing.
Ključne besede: rechargeable alkaline battery, thermal runaway, battery degradation, MnO2, Zn, zinc, X-ray microtomography
Objavljeno v DiRROS: 23.05.2025; Ogledov: 632; Prenosov: 434
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Povzetek: Red mud (RM) is an extractive waste from Bayer process in alumina production. The most conventional methods of RM disposal are tailing dams, or dry storage,both of which raiseenvironmental concerns due to the high alkalinity of RMandthe presence and leaching of potentially hazardous elements (PTEs).Due to its fine-grained nature and poor mechanical properties, as well as leaching of potentially hazardous substances, RM cannot be used by itself. Properties of the RM can be improved, by mixing it with hydraulic or pozzolanic binders, such as calcareous ashes or steelmaking slag, to produce mechanically stable and durable composites for earthworks. On the other hand, RMcan also serve as an immobilization additive for remediation of contaminated soils.Two different approaches for useful utilization of RMare presented based on results of laboratory research and a real case study, opening of new possibilities for conserving natural resources and reducing environmental hazards of RM deposits.
Ključne besede: red mud, recycling, geotechnical composites, environment
Objavljeno v DiRROS: 30.10.2024; Ogledov: 943; Prenosov: 1173
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Povzetek: Fine particulate matter (PM2.5), a detrimental urban air pollutant primarily emitted by traffic and biomass burning, poses disproportionately significant health risks at relatively limited exposure during commuting. Previous studies have mainly focused on fixed locations when assessing PM2.5 exposure, while neglecting pedestrians and cyclists, who often experience higher pollution levels. In response, this research aimed to independently validate the effectiveness of bicycle-mounted low-cost sensors (LCS) adopted by citizens, evaluate temporal and spatial PM2.5 exposure, and assess associated health risks in Ljubljana, Slovenia. The LCS quality assurance results, verified by co-location field tests by air quality monitoring stations (AQMS), showed comparable outcomes with an average percentage difference of 21.29 %, attributed to humidity-induced nucleation effects. The colder months exhibited the highest air pollution levels (μ = 32.31 μg/m3) due to frequent thermal inversions and weak wind circulation, hindering vertical air mixing and the adequate dispersion of pollutants. Additionally, PM2.5 levels in all sampling periods were lowest in the afternoon (μ = 12.09 μg/m3) and highest during the night (μ = 61.00 μg/m3) when the planetary boundary layer thins, leading to the trapping of pollutants near the surface, thus significantly affecting diurnal and seasonal patterns. Analysis of exposure factors revealed that cyclists were approximately three times more exposed than pedestrians. However, the toxicological risk assessment indicated a minimal potential risk of PM2.5 exposure. The collaborative integration of data from official AQMS and LCS can enhance evidence-based policy-making processes and facilitates the realignment of effective regulatory frameworks to reduce urban air pollution.
Ključne besede: air pollution monitoring, PM2.5 exposure, citizen science, bicycle-mounted low-cost sensors
Objavljeno v DiRROS: 30.01.2024; Ogledov: 1865; Prenosov: 735
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Povzetek: We live in a material world where the markets are flooded with all kinds of products. At the same time, we are facing a population growth, as well as a product demand growth. But, are we aware of the raw materials needed for our favourite daily products? In which part of the world are they extracted? Do we recognize the value chains from the mine to the product? And, where do these products end up after we use them? Many school curriculums include this topic only briefly, thus there is a need to raise awareness among youngsters about mining and raw materials in general. EIT RawMaterials funded by the European Commission, is the largest community dealing with raw materials in Europe. One of its main objectives is to raise awareness among general public about the raw materials and their indispensability, about the consequences of their uses, about the mining and production systems as well as about the utilization and recycling. Innovative and attractive pathways are employed in the process. One of the projects bringing raw materials and mining closer to pupils is the BRIEFCASE project. Using non - conventional teaching methods, tools and guided workshops, the project provides pupils with a unique hands - on experience. It draws their attention to raw materials and their applications and helps pupils recognize minerals in products we use every day. Besides emphasizing the importance of minerals in our everyday life and addressing sensible issues like conflict minerals, the consequences of our purchase decisions, the sustainability of mining operations and their environmental implications are also presented.
Ključne besede: Project BRIEFCASE, minerals, raising awareness, non-conventional teaching tools, EIT RawMaterials, award
Objavljeno v DiRROS: 21.11.2023; Ogledov: 1805; Prenosov: 654
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