Search Results (740)

Fireworks are widely used at festive events worldwide and are commonly employed at indoor wedding ceremonies in Türkiye; however, their impact on indoor air quality has not been adequately investigated. This study examines particulate matter (PM) emissions generated by volcano-type fireworks used in indoor wedding halls. Particle samples were collected across five size fractions (>2.5, 1.0–2.5, 0.50–1.0, 0.25–0.50, and <0.25 µm) using a 5-stage Sioutas cascade impactor, and elemental compositions were determined by ICP-MS. PM_2.5 concentrations ranged between 1518 and 7796 µg/m³, while total PM concentrations varied between 2088 and 8656 µg/m³. These values are substantially higher than the guideline limits reported by the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA), indicating very high short-term exposure levels. Fine particles (PM_2.5) accounted for 56.5–92.4% of total PM, with particles smaller than 1 µm forming the dominant fraction. Among the analyzed elements, aluminum (Al), zinc (Zn), and iron (Fe) were the most abundant metals, predominantly associated with fine particles. The highest concentrations were generally observed in the 0.25–0.5 µm size range. These findings showed that the use of indoor fireworks can lead to high concentrations of fine particulate matter and metal-rich aerosols. This issue should be considered, as it may pose a health risk for those in enclosed spaces in future studies. Full article

To comprehensively investigate the aerosol optical properties and vertical structures over the northeastern Tibetan Plateau (TP), a field campaign was conducted from January to August 2023 in the Hainan Tibetan Autonomous Prefecture. Ground-based sunphotometer measurements yielded a mean aerosol optical depth (AOD) of 0.18 and an Ångström exponent (AE) of 1.20 over the study period. The lowest AE, observed in April alongside the highest aerosol loading, suggests a predominance of dust aerosols during this period. This finding is further supported by the elevated vertical extinction profiles derived from LiDAR measurements, indicating long-range transboundary transport of dust aerosols from northern desert regions. Ground-based AOD measurements were used to validate satellite-derived MODIS retrievals and the assimilated MERRA-2 reanalysis product. Among the aerosol types examined, dust aerosols exhibited the highest accuracy in both AOD and AE validation. MERRA-2 was found to systematically underestimate AOD by 22% and AE by 35%. Nevertheless, due to its tighter expected error envelope, lower overall errors, and superior temporal continuity and spatial coverage, MERRA-2 remains a reliable data source for subsequent analyses. A long-term analysis spanning 2006 to 2025 identifies 2011 as a turning point, after which AOD declined at a rate of 0.0022 per year. This sustained reduction highlights the effectiveness of China’s air pollution prevention and control policies. Collectively, these findings provide essential insights for refining satellite retrieval algorithms and aerosol–climate models over the TP. Full article

C. burnetii (Cb) is an obligate intracellular bacterial pathogen that replicates within alveolar macrophages following aerosol infection. Unlike most intracellular bacteria, Cb establishes a lysosome-derived replicative niche (Coxiella-containing vacuole or CCV) through the action of its Type IVB secretion system (T4BSS). This system translocates a large repertoire of effector proteins into the host cytoplasm after phagosome acidification. These effectors interfere with diverse signaling pathways to co-opt host processes, such as vesicle trafficking, ubiquitylation, gene expression and lipid metabolism, promoting pathogen survival without triggering robust proinflammatory signaling or host cell death pathways. This effector-triggered immune silencing is particularly unique given the central role of macrophages as innate immune sentinels. In this review, we examine Cb T4BSS effectors that have been characterized as central determinants of innate immunity modulation. We discuss innate immune sensing pathways potentially engaged during infection, including Toll-like receptors, NOD-like receptors, RIG-I-like receptors, inflammasomes, and interferon signaling pathways, and highlight evidence indicating that these pathways are actively suppressed. Emphasis is placed on effector-mediated regulation of NF-κB signaling, type I interferon responses, and inflammasome activation. Finally, we address unresolved questions related to effector-triggered immunity, redundancy in immune suppression, and discrepancies between in vitro and in vivo infection models. Full article

Non-exhaust particulate emissions are expected to remain a relevant source of traffic-related air pollution, including an increase in electrified vehicle fleets. Particle formation results from tribological interactions and is influenced by both operating conditions and friction material system. This study presents an extended measurement methodology under application-relevant tribological conditions for the reproducible quantification of PM₁₀ and PM_2.5 emissions from dry-running friction systems and applies it to a systematic investigation of operating parameter and friction pairing effects. A dry inertial brake test bench with an enclosed friction chamber and integrated aerosol measurement chain was used under controlled tribologically relevant conditions. Specific friction work and specific friction power were varied by adjusting sliding velocity, contact pressure, and inertial load. Six friction pairings, comprising four representative friction lining types combined with either C45 cast steel or GGG40 gray cast iron, were examined. In situ PM₁₀ and PM_2.5 measurements were complemented by gravimetric wear and microstructural analyses. The results show that specific friction work has a direct influence on PM₁₀ and PM_2.5 emissions, whereas the independent effect of contact pressure is secondary. Friction power exhibits material-dependent effects. Emissions also vary strongly with friction pairing, indicating that operating conditions and material system must be considered jointly when assessing low-emission brake systems. Full article

Heavy precipitation in Northeast China is frequently modulated by the Northeast China Cold Vortex (NCCV), although the microphysical processes within squall lines under such conditions remain insufficiently understood. This study presents a comprehensive analysis of an NCCV-influenced squall line in Liaoning Province, utilizing coordinated S-band polarimetric radar and surface disdrometer observations. The raindrop size distribution (DSD) characteristics and three-dimensional microphysical structure are systematically examined for both convective and stratiform regimes. A comparative analysis of DSD and warm-rain microphysical mechanisms is also conducted with a Mei-yu event. Results show that convective rain in the NCCV squall line exhibits a continental-type DSD, characterized by fewer but larger raindrops compared to other heavy rainfalls in China. In contrast, the Mei-yu frontal convection under NCCV influence exhibits a transitional DSD pattern between the maritime and continental types, with raindrops smaller and denser than those in the NCCV squall line. Vertical structure of the mature squall line shows prominent differential reflectivity (Z_DR) and specific differential phase (K_DP) columns above the melting level within the convective region, indicating vigorous riming growth of graupel and hail driven by strong updrafts. Meanwhile, the stratiform region is characterized by ice crystals and aggregates, formed primarily through deposition and aggregation processes. The subsequent melting of ice-phase particles followed by collision–coalescence and evaporation-driven size sorting shapes the large but sparse raindrops in the NCCV squall line. Comparison with Mei-yu convection demonstrates that surface DSD is shaped by environmental conditions and vertical microphysics. The drier, more unstable environment in the NCCV squall line favors deep convection with active ice-phase processes, while the relatively moist and stable environment of the Mei-yu convection supports shallower convection dominated by warm-rain processes. Future multi-case studies with integrated observations are needed to quantify how environmental and aerosol conditions modulate these heavy precipitation processes. Full article

Aerosol optical depth (AOD), fine-mode fraction (FMF), and absorption aerosol optical depth (AAOD) are essential for quantifying aerosol extinction and related climate and air-quality effects. Yet, most satellite retrievals target a single wavelength or parameter. In this study, a deep neural network (DNN) framework was developed to synergistically retrieve AOD, FMF, and AAOD from Sentinel-5P/TROPOMI at seven wavelengths across 380–772 nm. Parameter-specific feature engineering was designed by incorporating physical linkages among aerosol optical properties. Bayesian optimization was employed to tune hyperparameters, and SHAP (Shapley additive explanations) was used to interpret feature contributions. The proposed model demonstrated high accuracy and robustness on an independent test set. The retrieved AOD showed excellent agreement with AERONET (R = 0.960, MAE = 0.034, RMSE = 0.070), and similarly strong performance was achieved for FMF (R = 0.955, MAE = 0.027, RMSE = 0.039). For AAOD, an overall correlation of 0.86 was obtained (MAE = 0.005, RMSE = 0.008). Comparisons with existing satellite products indicated globally consistent spatial patterns and improved spatial continuity under high aerosol loading. Overall, the proposed data-driven approach enhances the efficiency and coverage of multi-parameter aerosol retrieval while maintaining high accuracy, supporting absorbing aerosol monitoring, aerosol-type discrimination, and climate-effect assessment. Full article

The object of the study is a single heated carbonaceous particle of relatively small size, 0.003 to 0.01 m. Main hypothesis: The formation of soot particles and black carbon particles is caused by the thermochemical destruction of dry organic matter of forest fuel and the mechanical fragmentation of coke residue. The aim of the study is to conduct numerical simulations of heat and mass transfer in a single heated carbonaceous particle, taking into account the soot formation process and assessing its fragmentation with regard to heat exchange with the external environment in a 2D setting. As part of this study, a new model of heat and mass transfer in a pyrolyzed carbonaceous particle was developed, taking into account its step-by-step fragmentation (fragmentation tree model with four secondary particle formations from the initial particle). The calculations resulted in the distributions of temperature and volume fractions of phases in the carbonaceous particle across various scenarios. Scenarios of surface fires (initial temperatures of 900 K and 1000 K), crown fires (1100 K), and a firestorm (1200 K) for typical vegetation (pine, spruce, birch) are considered. Cubic carbonaceous particles are considered in the approximation of a 2D mathematical model. To describe heat and mass transfer in the structure of the carbonaceous particle, a differential equation of thermal conductivity with corresponding initial and boundary conditions of the third type is used, taking into account the gross reaction in the kinetic scheme of pyrolysis and soot formation. Differential analogues of partial differential equations are solved using the finite difference method of second-order approximation. Options for using the developed mathematical model and probabilistic fragmentation criterion for assessing aerosol emissions are proposed. Recommendations: The suggested mathematical model must be incorporated with mathematical models of forest fire plume and aerosol transport in the upper layers of the atmosphere. Moreover, probabilistic criteria for health assessment must be developed for the practical use of the suggested mathematical model. Full article

The vertical distribution of atmospheric aerosol layers plays a fundamental role in understanding their climatic and environmental effects. Using one year of lidar observations in Jinhua, together with ground-based meteorological measurements and ERA5 reanalysis data, this study develops an integrated analytical framework to investigate the structural characteristics of aerosol layers in Mie-scattering profiles and their meteorological driving factors. K-means clustering identifies three representative aerosol layer structure types: single-layer concave, single-layer convex, and multi-layer profiles. By combining the Boruta algorithm with a random forest model, the dominant meteorological factors associated with each structure type are quantified across four boundary-layer stages (00–06, 06–12, 12–18, 18–24 LT). Temperature, humidity, wind speed, wind direction, divergence, and vertical velocity exhibit distinct influences across different boundary-layer conditions, revealing differentiated regulatory mechanisms governing aerosol layer structure change. The proposed framework establishes a coupled perspective between atmospheric dynamic/thermodynamic processes and aerosol layer structure formation, providing a basis for refined modeling of aerosol evolution and improved understanding of aerosol–meteorology interactions. Full article

Bacilus cereus and Pseudomonas fluorescens are major foodborne psychrotrophic bacteria posing global health and economic risks. B. cereus has a 23.8% food prevalence worldwide. P. fluorescens is a leading cause of spoilage in refrigerated products. Their rapid detection is crucial for food safety. However, existing detection methods often rely on open-tube operations, risking aerosol contamination. In this study, we developed two independent one-tube RPA-CRISPR/Cas12a visual detection assays for B. cereus and P. fluorescens. Using a physical separation design, the recombinase polymerase amplification (RPA) and CRISPR/Cas12a detection were pre-assembled in a single reaction tube. After incubation, a brief centrifugation combined the components for enclosed detection. This step is compatible with portable mini-centrifuges. The assays can be completed within 40 min at 37 °C, with results visualized directly under blue light. Both assays demonstrated good specificity against six common non-target pathogens. The visual detection limits were 5.1 × 10¹ copies/μL for B. cereus and 2.1 × 10¹ copies/μL for P. fluorescens. Each assay was applied to 14 types of real-world food samples (naturally contaminated and uncontaminated, confirmed by PCR), achieving 100% concordance with conventional PCR. The one-tube assays are tailored for psychrotrophic bacteria in refrigerated foods. They minimize aerosol contamination risk and provide a reliable solution for on-site cold-chain food safety monitoring. Full article

The growing popularity of electronic cigarettes (e-cigarettes) necessitates a better understanding of their biological effects. In this study, we aimed to evaluate the effects of e-cigarette aerosol condensates generated from either e-cigarette carrier liquid alone or with e-cigarette liquid with nicotine and flavor on bronchial epithelial cells. BEAS-2B cells were exposed to e-cigarettes for 24 h, and transcriptional and proteomic profiling, including assessment of protein modifications, was performed. Additionally, cell-based assays were used to evaluate mitochondrial function, rate of protein synthesis, lysosomal signal, lipid droplet quantity and actin formation. Our findings reveal that short-term exposure to both types of aerosol condensates altered transcriptome and proteome profiles, disrupting cellular homeostasis in BEAS-2B cells through impaired proteostasis and mitochondrial function in response to both types of condensates. Changes in lipid and lysosome content, as well as a reduction in polymerized actin, were observed with nicotine- and flavor-containing condensate. E-cigarette exposure also induced irreversible protein modifications, including different chemical derivatives (25 out of 49 in nicotine/flavor condensate; 20 out of 48 in nicotine/flavor-free condensate; 4 out of 35 in control), suggesting their particularly harmful effect. Together, these findings point to early-onset cellular stress and impaired lung epithelial fitness caused by acute e-cigarette exposure. Full article

Polar Stratospheric Clouds (PSC) have been observed by the lidar observatory at Concordia station since 2014. The Concordia lidar is one of a few primary lidar stations in Antarctica of the Network for the Detection of Atmospheric Composition Change (NDACC). The lidar system was deployed at McMurdo from 2004 to 2010 and has been upgraded before its installation at Concordia. Concordia station is one of the most favourable locations for the observation of polar stratospheric clouds, due to the limited cloud cover by tropospheric clouds and the ubiquitous presence of PSCs throughout the Antarctic winter. The PSCs observations have been synchronized with the overpasses of satellite borne lidars, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) on the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite from 2014 to June 2023, and the Atmospheric Lidar (ATLID) on the EarthCARE (Earth, Cloud, Aerosol and Radiation Explorer) mission since September 2024. A modified v2 algorithm, used for the detection and classification of PSCs as observed by CALIOP, has been used to determine detection limits and classification criteria. This facilitates comparison with CALIOP PSC profiles during quasi-coincident overpasses of the CALIPSO with respect to Concordia station. A local PSC climatology has been produced, with typically more than 150 profiles per PSC season. Considerable inter-annual variations have been observed, mostly depending on the local temperature. The data have been used to infer a decadal trend of PSC occurrences, although the large inter-annual variability renders such an approach difficult. The occurrences of the different PSC types show a strong correlation with the local temperature and depend on the formation processes and the formation temperatures of the different PSCs. Full article

Numerical simulations of (1) two aerosol types such as organic carbon (i.e., spherical) and dust (i.e., non-spherical) particles, and (2) their mixtures are carried out. Optical and microphysical parameters of these aerosols in our simulations are provided by MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2). The inversion routine is performed with TiARA (Tikhonov Advanced Regularization Algorithm) using the Lorenz–Mie (i.e., spherical) light-scattering model in unsupervised and automated, i.e., autonomous mode. The results of our numerical simulations show that the accuracy of the inversion results for the aerosol mixtures from synthetic optical data perturbed by ±10% random error is comparable to the accuracy observed for the inversion results of the “pure” spherical particles. In particular, the retrieval uncertainties of effective radius, and number, surface-area, and volume concentrations of these mixtures are ±30%, ±10%, between −50% and +100% and ±30%, respectively. However, we need to apply a modified version of the gradient correlation method (GCM) to stabilize the inversion results. The results of this study will form the baseline for future work, where we plan to apply TiARA to optical data products obtained from real lidar observations in the framework of the SCC (Single Calculus Chain) of EARLINET (European Aerosol Research Lidar Network). Full article

Legionella species are ubiquitous bacteria found worldwide in water, moist environments, soils, and compost. Infection occurs through the inhalation of aerosols, leading to either Pontiac fever or Legionnaires’ disease (LD). Current routine diagnostics typically combine culture-based isolation with Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for species identification and the Latex Agglutination Test (LAT) for serotyping. However, this workflow is fragmented: MALDI-TOF MS lacks serogroup-specific resolution, while LAT relies on subjective visual interpretation. Therefore, this study evaluated Fourier-transform infrared spectroscopy (FT-IR) as a rapid, high-resolution typing method for Legionella isolates to assess its potential as a single-step diagnostic tool. A total of 200 clinical and environmental Legionella isolates were analyzed using FT-IR, including L. pneumophila serogroups (SG) 1–15 and various non-pneumophila species. Spectral data were analyzed using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA). While MALDI-TOF MS provided accurate species identification, FT-IR spectroscopy demonstrated superior typing capabilities by successfully distinguishing L. pneumophila SG 1 distinct from the SG 2–15 complex and allowing for clear discrimination of most non-pneumophila species. Additionally, FT-IR resolved isolates that showed ambiguous or non-reactive results in LAT. These findings demonstrate that FT-IR overcomes the serotyping limitations of MALDI-TOF MS and offers a more objective, cost-efficient extension to the current multi-step routine, potentially closing the diagnostic gap between simple species identification and deep strain characterization. Full article

We present an improved algorithm based on the POlarization LIdar PHOtometer Networking (POLIPHON) method to retrieve cloud condensation nuclei (CCN) concentration profiles from spaceborne lidar observations. Our previous paper, which was the first study to demonstrate the feasibility of using measurements from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) to retrieve CCN is revisited. Our results focus on the Evaluation of CALIPSO’s Aerosol Classification scheme over Eastern Mediterranean (ACEMED) research campaign that took place over Thessaloniki, Greece, in September 2011. We compare our results with our earlier retrievals, discussing the critical changes that have been made and the importance of using the proper conversions factors. We also demonstrate the use of conversion factors acquired based on CALIPSO aerosol typing for CCN retrievals. The analysis highlights the strong influence of smoke on CCN concentrations and shows that the assumed aging state of the smoke can significantly alter the retrieval outcome. Full article

Although the organic fraction of PM_2.5 has been extensively studied, there is a considerable gap in understanding the organic fraction of coarse particles with diameters between 2.5 and 10 µm. We investigate the composition of coarse organic aerosol (OA) across rural, suburban, and urban areas of Switzerland. Using Aerosol Mass Spectrometer analyses of water-soluble OA extracted from collected filter samples (one entire year, 441 samples per size fraction), we identified two distinct classes of coarse OA. The first class, which constitutes 41–81% of coarse organic carbon (OC), is associated with primary biological organic carbon (PBOC). PBOC is characterized by specific marker ions (e.g., C₂H₅O₂⁺) and exhibits pronounced seasonal variation, with peak concentrations observed in the summer. This seasonal trend correlates with that of molecular markers such as arabitol and mannitol, as well as the fraction of biological particles determined by automated scanning electron microscopy coupled to energy dispersive X-ray spectroscopy of individual particles. The second class, contributing 7.9–17.8% to OC_coarse, is denoted as sulfur-containing organic carbon (SCOC) due to the presence of sulfur-containing ions such as CH₃SO₂⁺. Elevated concentrations of SCOC in urban environments near roadways suggest a strong influence from non-exhaust traffic emissions and resuspended dust. While the overall variation in coarse OC between rural and urban areas is approximately 10%, PBOC concentrations are 1.4 times higher in rural areas, whereas SCOC concentrations are 1.5 times higher in urban settings. Overall, our study shows that although OC_coarse concentrations in Switzerland are relatively consistent across site types, major water-soluble sources, particle properties and composition vary considerably geographically and seasonally. Full article