Air-liquid interface (ALI) systems have emerged as a physiologically relevant in vitro platform for evaluating the toxicological impact and potential health effects of airborne pollutants. When utilizing collected ultrafine particles (UFPs), application volume and liquid type are critical parameters. Using a smaller volume of liquid for the cell exposure results in a heterogeneous distribution of UFPs across the cell monolayer, whereas application of a sufficient volume optimises even UFP distribution. A buffered solution for UFP administration minimises potential side effects and unravels dose-dependent effects in toxicological endpoints. However, standardised exposure methodologies limit reproducibility and comparability across studies. Therefore, we propose a refined manual exposure technique of suspended airborne pollutants in an adequate exposure volume that bridges the gap between conventional submerged cultures and ALI systems. Our model uses cell culture inserts with A549 epithelial cells, THP-1 macrophages, and EA.hy926 endothelial cells to mimic the in vivo alveolar barrier within the lungs. This approach offers a balance of experimental reproducibility whilst addressing the current challenges of standardisation and feasibility in exposure studies with manual UFP exposure. In conjunction with existing aerosol ALI continuous flow exposure systems, our studies are advancing translational in vitro evaluations, aligning with the 3R principle.

Improving mitochondrial health by pyrroloquinoline quinone (PQQ) prevents ultrafine carbon particle (UFCP) induced emphysema and associated pulmonary hypertension.

As green hydrogen production via proton exchange membrane water electrolyzers (PEMELs) continues to scale up, the development of effective recycling processes for end-of-life components is becoming increasingly important. In PEMELs, ultrafine catalyst particles exhibit significant differences in hydrophobicity, which serve as a basis for selective separation. In this study, two separation techniques based on hydrophobicity differences (liquid–liquid particle separation and emulsion-based froth flotation) were proposed for particle recovery. Since catalyst inks contain amphiphilic ionomers as binders in addition to the particles, their influence on wettability-based separation was investigated. To clarify this effect, we investigated the physicochemical characteristics of ionomer-coated particles. Key parameters such as particle size, surface area (BET), and zeta potential were measured, and their impact on wettability was assessed. The results show that ionomer adsorption leads to a notable reduction in the hydrophobicity contrast, thereby hindering their selective separation. To address this issue, a dispersant was introduced to both separation processes. This addition improved the recovery performance, under conditions where the hydrophobicity difference was reduced (LLPS: recovery increased from 10 % to 70 %, froth flotation: approx. 15 % improvement). Although the addition of dispersants improved the recovery performance, the separation efficiency remained lower than that observed under ionomer-free conditions (over 95 % of recoveries in both processes). The findings highlight the complex interactions between particles, ionomers, and reagents in dispersion systems. Further investigation into these interactions is necessary to develop more robust and scalable recycling strategies. A deeper understanding of the physicochemical mechanisms will provide valuable insight into the design of selective separation processes for catalyst recovery in PEMEL systems.

About half of patients with chronic obstructive pulmonary disease (COPD) have hypertension, which significantly worsens prognosis. Yet its critical environmental drivers and vulnerable phenotypes remain unclear. To evaluate associations between size-fractionated particulate matter (PM) and blood pressure, assess differential effects by hypertension status and identify susceptible individuals by smoking and inflammatory phenotypes. In this prospective panel study, 82 patients with COPD (42 with hypertension) completed 281 clinical visits. Personal exposure to ambient inhalable PM (PM10), fine PM (PM2.5) and ultrafine particles (UFPs) of 0-7 days was estimated using infiltration factors and time-activity patterns. Inflammatory phenotypes were defined by blood neutrophils and eosinophils. Linear mixed-effect models were applied to evaluate blood pressure changes associated with PM. UFPs and PM2.5, rather than PM10, were significantly associated with increased systolic blood pressure (SBP), whereas diastolic blood pressure (DBP) and pulse pressure showed non-significant changes. The effects appeared earlier after UFP exposure (lag 03d) than PM2.5 exposure (lag 06d), with central responses exceeding brachial responses. Notably, hypertensive individuals exhibited stronger responses to UFPs and PM2.5 exposure, in whom significant elevations were observed in both SBP and DBP. Stratification by smoking status revealed no evidence of effect modification. Comparatively, individuals with an eosinophilic, instead of neutrophilic, phenotype showed heightened susceptibility to PM2.5-related and UFP-related blood pressure increases, particularly in those with hypertension. Small-sized PM is an important risk factor for blood pressure elevations in patients with COPD, especially among those with hypertension and an eosinophilic inflammatory phenotype. NCT05076630.

The use of aeolian sand as a fine aggregate in concrete production provides a sustainable pathway to valorize abundant aeolian resources while alleviating the global shortage of natural construction aggregates. However, the high ultrafine particle content of aeolian sand results in the formation of highly porous interfacial transition zones (ITZ) between sand particles and cement paste, which is the primary cause of the inherent brittleness and inferior mechanical performance of aeolian sand concrete. To overcome this critical limitation, an alkali-activated surface layer (ASL) was constructed on aeolian sand via 4 mol/L KOH activation. This process induced the surface micro-dissolution of minerals to create high-density active ion sites (specifically Ca2+, K+, Na+, and Fe3+). These sites facilitated the precise anchoring of carbon nanotubes (CNTs) through the chemical coordination of single-stranded deoxyribonucleic acid (ssDNA). The influence of the ASL and the ssDNA/CNTs nanocomposite on the ITZ was elucidated through macro-mechanical testing and multi-scale microstructural characterization. Experimental results demonstrated that compressive strength, flexural strength, and compressive energy dissipation increased by 48%, 67%, and 42%, respectively. Microstructurally, the modification promoted a pore refinement mechanism, reducing the proportion of harmful (pores > 0.1 μm) from 51% to 20% and narrowing the ITZ width from 20-40 μm to 10-15 μm (a 67% reduction). The observed performance enhancement is attributed to the synergistic effect of the ASL and ssDNA/CNTs, which transforms the inherently weak ITZ into a chemically reinforced interfacial phase via molecular-scale coordination bonding and optimized stacking of cement hydration products.

Firefighters are exposed to complex combustion products and to contaminants carried on personal protective equipment (PPE). Occupational exposure as a firefighter is classified as carcinogenic. This review summarizes the current evidence on exposure environments, routes of uptake, contamination and secondary exposure from PPE, and the effectiveness and limits of decontamination approaches. Across incident types, smoke composition varies with the fuels and combustion conditions, but fine and ultrafine particles and semi-volatile organic chemicals are common. Biomonitoring confirms uptake after incidents. Self-contained breathing apparatus reduces inhalation exposure during active suppression, yet exposures persist through dermal absorption at ensemble interfaces and post-incident tasks. Protective ensembles can retain soot-bound polycyclic aromatic hydrocarbons, additive chemicals, and metals; volatiles and particles resuspension in vehicles and stations can extend exposure. Studies show that on-scene preliminary exposure reduction and laundering can lower contaminant burdens on PPE; however, removal remains incomplete and decreases when cleaning is delayed or when gear is aged. Emerging evidence raises additional concern for per- and polyfluoroalkyl substances from foams and coating materials, with limited data on exposure metrics and removability. The field lacks standardized, realistic contamination platforms and a dose-based definition of clean PPE. Integrated intervention studies linking exposure, secondary exposure pathways, biomarkers, and decontamination methods are needed to set performance-based targets and evaluate emerging hazards.

Abstract. Per- and polyfluoroalkyl substances (PFAS) are recognised as atmospheric contaminants, yet processes governing their aerosol formation, size distribution, and interactions with atmospheric particle surfaces remain unknown. We investigated aerosolisation and size-resolved behaviour of 25 PFAS covering short-, medium-, and long-chain perfluoroalkyl carboxylic acids (PFCA), perfluoroalkane sulfonates, fluorotelomer sulfonates and emerging alternatives. Experiments were conducted under controlled chamber conditions using a water–organic solvent system, in the absence/presence of the model bacterium Pseudomonas fluorescens seed to investigate the potential influence of microbial presence on PFAS behaviour. Most PFAS exhibited unimodal mass–size distributions peaking at 0.3 µm, indicating dominant association with the fine mode. Sulfonated PFAS showed broadly similar aerosol-phase concentrations regardless of carbon-chain length, whereas PFCA displayed increasing aerosolisation with chain length. Perfluorooctane sulfonic acid (PFOS) showed additional ultrafine enrichment, 6:2 fluorotelomer sulfonate (6:2 FTS) and sodium 4,8-dioxa-3H-perfluorononanoate (NaDONA) exhibited broader size profiles, suggesting compound-specific effects linked to volatility and interfacial behaviour. Pseudomonas fluorescens seed did not enhance PFAS aerosol concentrations through condensation or heterogeneous uptake onto bacterial particles or shift in modal diameters, and no enrichment was observed at bacterial size mode, indicating limited PFAS–bioaerosol association under the tested conditions. Multiple-Path Particle Dosimetry (MPPD) modelling based on the measured size distributions predicted substantial deposition of the aerosol-bound PFAS in the pulmonary region, particularly for compounds enriched in ultrafine particles. Our findings indicate that PFAS aerosol behaviour in mixed-solvent systems is controlled primarily by physical droplet generation and evaporation, with implications for airborne transport and inhalation exposure from contaminated aqueous sources.

Investigating the inflammatory response to exposure of ultrafine TiO2 particulate matter to HUVECs.

Spatial and spectral mapping of traffic-related nanoparticles in hippocampal subregions of an Alzheimer disease model.

Characterization of ultrafine particle and chlorine emissions from sodium hypochlorite disinfection: Experimental measurements and exposure modelling in healthcare settings.

Linking particulate matter exposure and neurological disorders: Evidence from epidemiology, biomarkers and mechanistic studies.

Circular economy (CE), particularly closed-loop recycling, has been identified as a strategy to enhance the sustainability of the cement industry. The chemical composition of the raw meal - the raw materials used to produce cement - is a limiting factor in cement manufacturing, particularly for CE and end-of-life (EOL) concrete recycling. Cement closed-loop recycling entails retrieving ultrafine concrete waste particles (UFCWP, particle fraction between 0 and 0.25 mm) from EOL concrete using advanced recycling technologies that could replace clinker raw meal in cement clinker manufacturing. Utilizing a combined conceptual stoichiometry mass balance model with material flow analysis for the first time, this study demonstrates the chemical limitations of substituting raw materials with ultrafine EOL concrete in a closed-loop recycling process within the Danish clinker production. The main results indicate that a maximum of 11.76% UFCWP can be used to replace conventional raw meal in Danish cement clinker production, resulting in a 10% reduction in global warming potential compared to conventional cement clinker production. For this, we would require three times more EOL CEM I concrete in Denmark than is currently produced (approx 1.2 Mton). This study highlights the mismatch between current cement demand and EOL concrete for closed-loop recycling in Denmark.

Context-dependent dominance: Pollution sources vs. tree species in shaping leaf-deposited PM characteristics.

Ultrafine particle formation across urban and background sites: Insights on Midday Pollution events through analysis of locally emitted pollutants

Previously reported rooftop ambient aerosol measurements in Raleigh, NC, USA, detected episodic events where sub-10nm particle number concentrations (PNC) exceeded 3.73×105cm-3. Their small size and temporally stable modal diameter (sometimes persisting for days) indicated origins from nearby primary emission sources rather than mesoscale new particle formation (NPF) events. To investigate potential sources, simulations were conducted using the U.S. Environmental Protection Agency's Gaussian plume-based model, AERMOD. Campus surveys and Google Earth analyses identified three candidate sources near the measurement site, including two combined heat and power (CHP) facilities with high-efficiency natural gas turbines and heat recovery steam generators that provide energy to NC State's campus. Distinct point sources were modeled for each facility using an emission factor of 5×10-4gs-1. The study explored source contributions under varying micrometeorological conditions (e.g., wind speed, wind direction, solar radiation, and planetary boundary layer height). Wind pattern analysis revealed distinct plumes from individual power plants reaching the receptor site. Statistical analyses confirmed wind direction and speed as the strongest predictors of modeled mass concentrations, and that observed PNC profiles during NPF and particle burst events are fundamentally distinct. Exceptionally high sub-10nm particle growth rates were observed during plume transport, averaging 104-120nmhr-1. These findings reveal that expanding deployment of CHPs for distributed power generation may pose unrecognized health risks through sub-10nm particle emissions with demonstrated respiratory and neurological impacts. New emission standards may be needed to address ultrafine particle production from natural gas combustion technologies.

Occupational exposure to wood dust is a major public health and occupational safety concern, particularly in woodworking, furniture production, and the wood-based materials industry. Its carcinogenic, allergenic, and toxic potential depends on wood species, physicochemical properties, processing methods, and applied chemical treatments. The aim of this review was to analyze occupational exposure to wood dust by synthesizing current evidence on worker health risks, measurement methods, legal regulations, and preventive strategies, in order to evaluate the adequacy of existing solutions and identify areas requiring further improvement. The review is based on 61 literature sources: publications, legal acts, official guidelines from international and national institutions (International Agency for Research on Cancer, National Institute for Occupational Safety and Health, Occupational Safety and Health Administration, American Conference of Governmental Industrial Hygienists, European Agency for Safety and Health at Work, Statistics Poland, Nofer Institute of Occupational Medicine, Polish Ministry of Health). Sources published 2010-2024 were analyzed with particular focus on dust characteristics, exposure limits, measurement methods, preventive measures, and regulatory frameworks. Exposure to wood dust contributes to both acute and chronic respiratory conditions, skin and eye irritation, and a higher incidence of upper respiratory tract cancers. Recent regulatory changes have expanded the classification of wood dust as a carcinogen to include all species. Despite existing occupational exposure limits (OELs), exceedances remain common in woodworking industries. Conventional monitoring methods may underestimate respirable and ultrafine particles (UFP <100 nm), which pose substantial health risks. Preventive strategies - including technical controls, ventilation, personal protective equipment, and medical surveillance - significantly reduce airborne dust concentrations and worker exposure. Findings indicate a need to update OELs and harmonize regulations with current scientific evidence. Effective prevention requires integrating legal requirements, engineering controls, process automation, and medical and educational interventions. Strengthening national standards within the European Union regulatory framework and improving measurement methods - especially for inhalable and ultrafine fractions - are essential to ensuring adequate worker protection. Med Pr Work Health Saf. 2026;77(1):61-70.

Fault detection and diagnosis (FDD) are critical for maintaining efficiency and operational stability of comminution systems. However, conventional methods struggle to capture their complex dynamic behaviour, while data-driven approaches are constrained by limited labelled fault data and the need for interpretable diagnostic models. Progress is further hindered by the scarcity of publicly available industrial datasets. This study presents an explainable FDD framework that integrates unsupervised autoencoder (AE)-based anomaly detection with variance-based global sensitivity analysis (GSA) for quantitative fault diagnosis. A simulated comminution control system was developed to enable controlled validation under realistic operating variability. Multiple AE architectures were trained with hyperparameters optimised using chaotic particle swarm optimisation and evaluated using statistical and reconstruction-based metrics combined with multi-criteria decision analysis. The sparse AE achieved the best performance, with an MSE of 5.6 × 10−5, F1-score of 0.9930, and accuracy of 0.986 in detecting faults in P80 and P20. To diagnose detected faults, Sobol’s variance-based GSA was applied to quantify both the main and interaction effects of operational variables on particle size distribution. The results identify circuit feed rate, ball mill critical speed, and the pulp solids fraction supplied to the hydrocyclones as dominant drivers of faults associated with product coarsening, whereas circuit feed rate and ball mill critical speed primarily govern ultrafine particle generation. By integrating deep learning with explainable sensitivity analysis, this study advances transparent and quantitative diagnosis of complex mineral processing systems.

Abstract. Maritime transport exerts a substantial influence on local air quality, particularly in port cities. Ship emissions are recognized as major contributors to air pollution, with comparable magnitude to those of road transport. This study, conducted in 2021 in Toulon, a port city on the French Mediterranean coast, assessed ship emissions one year after the implementation of IMO2020 sulfur regulations. Emission factors (EFs) were determined for key pollutants such as SO2, NOx, CO, NO, CH4 and particulate matter (PM), including black carbon (BC), organics (Org), sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), and polycyclic aromatic hydrocarbons (PAHs), as well as the particle number concentration (PN). The IMO2020 regulation led to a marked reduction in sulfur-related emissions, whereas pollutants such as BC, Org, and PAHs remained at pre-regulation levels. Positive Matrix Factorization (PMF) analysis of PM1 organic aerosol (OA) measured by a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) was used to investigate shipping contribution to local air quality. PMF successfully distinguished between road and marine transport emissions, revealing a shipping contribution to the total OA of 11.2 %. Eight factors were resolved: three shipping-related OA, a Hydrocarbon-like OA (HOA), a Cooking-like OA (COA), an Oxidized Hydrocarbon-like OA (OxHOA), a Less Oxidized OA (LOOA), and a More Oxidized OA (MOOA). Shipping and HOA factors were the dominant contributors to ultrafine particles, accounting together for 51.9 % of the alkylated PAHs (APAHs). These findings highlight the persistent influence of shipping emissions in port areas and demonstrate the effectiveness of advanced source apportionment methods to improve emission monitoring strategies, particularly as the Mediterranean region prepares for the implementation of Emission Control Area (ECA) regulations in 2025.

Ultrafine particles (UFP) exhibit large spatial and temporal contrasts, and distinct physicochemical properties that enable deep lung penetration and systemic translocation, posing potential health risks. Despite mechanistic evidence from toxicological studies, large-scale epidemiological evidence remains limited due to sparse monitoring and complex exposure assessment. Switzerland has contributed substantially to UFP research through measurement campaigns, mobile monitoring, and modelling studies, which improved understanding of spatial and temporal exposure contrasts. Emerging findings suggest associations between long-term UFP exposure and cardiovascular indicators, though epidemiological evidence for short-term associations with mortality and morbidity remains weak. Ongoing Swiss and European projects aim to refine high-resolution spatiotemporal models, assess population-level health impacts, and inform future air quality standards and regulatory frameworks for UFPs.

Abstract. The monitoring of ultrafine particle concentrations in ambient air is gaining relevance within the revision of the EU Ambient Air Quality Directive. A prominent source of ultrafine particles (UFPs) is combustion processes (e.g., within the scope of wood-fired domestic heating), where the particle emission is typically led unfiltered into the environment, contributing significantly to local air pollution. In this study, ultrafine particle concentrations were measured in a residential area affected by wood smoke pollution during the winter months (20 November 2024–30 March 2025) using a diffusion-charge-based UFP monitor (AQ Guard Smart 2000 from Palas®). The measurements show a diurnal trend, where concentrations are significantly increased (e.g., &gt; 10 000 cm−3) above the background level (approx. 5000 cm−3) during the morning (approx. 08:00 CET) and evening hours (approx. 19:00–22:00 CET), whereby the source is wood smoke from the surrounding neighborhood. The dispersion conditions significantly affect the measured concentrations as, in the case of low (or zero) wind speeds only, increased UFP concentrations are obtained, demonstrating the relevance of local sources (wood stove operations) in relation to air quality. In the context of “good-practice statements” offered by the World Health Organization's Air Quality guidelines, the maximum daily 1 h mean concentration of 20 000 cm−3 is exceeded on approx. 33.6 % of days during the measurement period. This significant peak exposure on smaller timescales requires monitoring at a high temporal resolution as longer averaging periods (e.g., daily or annual mean concentrations) do not reflect temporal peak concentrations that can be especially dangerous for high-risk groups. There is no direct link between legally relevant particulate matter (e.g., PM2.5) and ultrafine particle concentrations as the size distribution of the wood smoke emission is in the nanometer region and does not contribute significantly to mass-based particulate matter concentrations.