A sampling device was developed for collecting and size-fractionating airborne particulate matter (PM). A low-volume cascade system with polytetrafluoroethylene membrane filters (PM₁₀, PM_2.5, and PM_0.1) connected to an ultrapure-water trap was used to retain the PM_<0.1 fraction that passed through the filters. In the collected samples, metal(oid)s and platinum group elements (PGEs) were determined by inductively coupled plasma mass spectrometry after microwave-assisted digestion using a mixture of acids. Polycyclic aromatic hydrocarbons (PAHs) were extracted with a solvent mixture of acetone and petroleum ether, assisted by mechanical shaking and determined by gas chromatography mass spectrometry. The analytical methods were optimised and validated using the urban PM Standard Reference Material 1648a. Measurement repeatability and accuracy were 6% and 2% for metal(oid)s and PGEs, and 3% and 6% for PAHs, respectively. Field emission scanning electron microscopy analysis confirmed that the sampling device efficiently fractionated airborne PM to nano-sized particles. The sampling device was successfully applied to collect PM, enabling effective air pollution monitoring in urban areas. Analysis revealed that metal(oid)s were most abundant in PM₁₀, while those originating from traffic were also elevated in PM_<0.1. High-molecular-weight PAHs were distributed between PM₁₀ and PM_2.5 fractions. The sampling device provides valuable insights into the chemical composition of (ultra)fine particles, overcoming the limitations of filter-based PM fractionation and providing improved air pollution control for nanoparticle-bound pollutants.

Laboratory and field assessments of low-cost sensors (LCS) are essential for ensuring the accuracy of PM_2.5 measurements collected by citizens in air quality campaigns. Evaluation of Sensirion SPS30 (LCS SPS30) in controlled laboratory setting showed a coefficient of determination (R ²) 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 R ² 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, R ² > 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 PM_2.5 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 PM_2.5 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.

Size-fractionated airborne particulate matter was collected over 1 year (2023-2024) at five urban pedestrian and cycling locations in Slovenia. PM₁₀, PM_2.5, PM_0.1 were collected using a low-volume sampler with polytetrafluoroethylene filters, and PM_<0.1 fraction was retained in ultrapure-water. Metal(loid)s and polycyclic aromatic hydrocarbons (PAHs) were determined to assess the potential health and environmental risks. Metal(loid) concentrations were the highest in PM₁₀, with most elevated levels of Zn (7 ng m^-3), Ba (4.5 ng m^-3), Cu (2.8 ng m^-3) and Cr (1.5 ng m^-3). Significant enrichment in PM_<0.1 was observed for Ba, Cu, Ni, Pb and Zn, with Ce-normalised values indicating a strong anthropogenic contribution. Tailpipe tracers were dominant in (ultra)fine PM fractions, while non-exhaust emission markers (Ba, Cu, Zn) strongly correlated with Ce and La in PM₁₀. Among PAHs, BbF (0.05 ng m^-3), BghiP and IP (0.04 ng m^-3) exhibited the highest concentrations. BaP, BghiP and IP were enriched in ultra-fine particles, indicating fresh vehicular combustion emissions. Peak pollutant concentrations occurred during the heating period (HP) and in densely populated, high-traffic cities. Source apportionment revealed a dominance of pyrogenic sources, including: (i) vehicular exhaust emissions from diesel engines (5-6-ring PAHs, Ni, V and Pb), (ii) resuspended mineral dust and non-exhaust traffic particles (Ba, Cu, Zn), and (iii) coal and biomass combustion during HP (4-ring PAHs, Co, Mo, Tl). Incremental lifetime cancer risk for As (2 × 10^-7), Co (1 × 10^-6) and Cr (6 × 10^-6) was minimal. Hazard quotient values were below 1. Children cycling during HP experienced the highest exposure levels. The European PM₁₀ limit values for As (6 ng m^-3), Cd (5 ng m^-3), Pb (500 ng m^-3), Ni (20 ng m^-3) and BaP (1 ng m^-3) were not exceeded.

Revitalisation of contaminated brownfield sites is essential for sustainable development, particularly near sensitive ecological areas like Natura 2000 sites. The lagoon in Slovenia’s Regional Park Šturmovci, an artificial wastewater convergence point created during hydroelectric construction, is a highly relevant example. This study integrates geochemical, mineralogical and isotopic analyses to identify sources and controlling mechanisms of contaminant distribution in lagoon sediments and assess their transfer to nearby agricultural soils during flooding events. Results indicate anaerobic conditions, with depth-related shifts in phosphorus, sulphur and redox-sensitive elements, such as rare earth elements (REE), arsenic (As), barium (Ba), cobalt (Co), chromium (Cr), lead (Pb) and vanadium (V), as well as fluctuations in pyrite-rich laminated layers, suggesting potential flood-driven remobilisation of trace elements. Lagoon sediments are highly contaminated with As (73 mg kg⁻¹), Ba (247 mg kg⁻¹), Pb (97 mg kg⁻¹) and Zn (1118 mg kg⁻¹), with elevated concentrations also observed in agricultural soil, all exceeding respective limit values of 20, 160, 85 and 200 mg kg⁻¹. Pollutant concentrations were highest near wastewater inflows and decreased with distance, with nitrogen isotopic patterns indicating partial nitrification and surface ammonium accumulation, reflecting intensive agricultural inputs in the area. High enrichment factor (EF > 20) and geoaccumulation index (I_geo > 3) values, in particular for As, Cd and Zn, indicated severe contamination and highlighted the urgent need for effective remediation strategies, including immobilisation using biochar or cement-based binders, as well as phytoremediation approaches.

The behavior and toxicity of particulate matter (PM) is primarily influenced by particle size and chemical composition, with fine (PM2.5) and ultrafine particles (PM0.1) posing the greatest health risks due to their deep respiratory penetration ability and enhanced adsorption capacity. While most studies focus on a single pollutant type – either organic or inorganic − using high-volume air samplers positioned far from areas commonly used by local commuters (e.g. rooftops), data on the multi-pollutant chemical composition of nanoparticles (PM1 or smaller) and their impacts on active commuters in urban environments remains scarce. A ground-level sampling device utilising a low-volume cascade system was employed to collect and fractionate PM-bound metal(oid)s and polycyclic aromatic hydrocarbons (PAHs), including in nanoparticles, over the course of one year in five urban areas across Slovenia, Europe. In the collected samples, metal(oid)s and PAHs were determined by inductively coupled plasma mass spectrometry following microwave-assisted acid digestion, and gas chromatography mass spectrometry after solvent extraction with mechanical shaking. The highest concentrations of metal(oid)s were predominantly found in PM10 (As, Cr, Ni, Pb) and PM