Search Results (1,093)

Understanding the dispersion of volcanic sulphur dioxide (SO₂) plumes is crucial for assessing their environmental and climatic impacts. This study integrates satellite-based and reanalysis datasets to simulate as well as visualise the dispersion patterns of volcanic SO₂ under diverse atmospheric conditions. By incorporating data from the MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, version 2), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations), and OMI (Ozone Monitoring Instrument) datasets, we are able to provide comprehensive insights into the vertical and horizontal trajectories of SO₂ plumes. The methodology involves modelling SO₂ dispersion across various atmospheric pressure surfaces, incorporating wind directions, wind speeds, and vertical column mass densities. This approach allows us to trace the evolution of SO₂ plumes from their source through varying meteorological conditions, capturing detailed vertical distributions and plume paths. Combining these datasets allows for a comprehensive analysis of both natural and human-induced factors affecting SO₂ dispersion. Visual and statistical interpretations in the paper reveal overall SO₂ concentrations, first injection dates, and dissipation patterns detected across altitudes of up to ±20 km in the stratosphere. This work highlights the significance of combining satellite-based and global atmospheric reanalysis datasets to validate and enhance the accuracy of plume dispersion models while having a general agreement that OMI daily data and MERRA-2 reanalysis hourly data are capable of accurately accounting for SO₂ plume dispersion patterns under varying meteorological conditions. Full article

Volatile phenols in the atmosphere are important precursors of ozone and secondary organic aerosols (SOAs). Despite their importance, the lack of effective observation and analysis methods has led to less attention paid to them, leading to gaps in our understanding of their behavior and effects on atmospheric chemistry. This study aimed to evaluate the concentration levels, sources, and environmental impacts of volatile phenols in ambient air, focusing on the urban area of Beijing and the suburban district of Heze in the North China Plain during winter. Samples were collected using an XAD-7 column and analyzed by high-performance liquid chromatography with ultraviolet detection (UPLC-UV). Results indicated that a higher concentration of 11 detected phenols was found in Beijing than that in Heze, with the average concentration of 23.60 ± 8.99 ppbv and 18.38 ± 2.34 ppbv. Phenol and cresol with strong photochemical activity were the predominant species, accounting for about 52% (Heze) and 66% (Beijing) of the total phenols, which indicates that more attention should be paid to volatile phenols in urban areas. Higher levels of L_OH in Beijing (36.86 s⁻¹) and Heze (22.06 s⁻¹) compared to other studies about PAMS and carbonyls indicated that these volatile phenols play an undeniable role in atmospheric oxidation reactions. Positive Matrix Factorization (PMF) identified major sources as pesticide usage (15.6%), organic chemicals (31.9%), and combustion or secondary conversion (52.5%). These findings underscore the multifaceted impact of phenols, influencing both gaseous pollutant concentrations and particulate matter formation, with potential implications for environmental and public health. Full article

In 2024, Brazil experienced record-breaking wildfire activity, underscoring the escalating influence of climate change. This study examines the long-range transport of wildfire-generated aerosol plumes to São Paulo, combining multi-platform observations to trace their origin and properties. During August and September—a period marked by intense fire outbreaks in Pará and Mato Grosso do Sul—lidar measurements performed at São Paulo detected pronounced aerosol plumes. To investigate their source and characteristics, we integrated data from the Earth Cloud Aerosol and Radiation Explorer (EarthCARE) satellite, HYSPLIT back-trajectory modeling, and ground-based AERONET and Raman lidar measurements. Aerosol properties were derived from aerosol optical depth (AOD), Ångström exponent, and lidar ratio (LR) retrievals. Back-trajectory analysis identified three transport pathways originating from active fire zones, with coinciding AOD values (0.7–1.1) and elevated LR (60–100 sr), indicative of dense smoke plumes. Compositional analysis revealed a significant black carbon component, implicating wildfires near Corumbá (Mato Grosso do Sul) and São Félix do Xingu (Pará) as probable emission sources. These findings highlight the efficacy of satellite-based lidar systems, such as Atmospheric Lidar (ATLID) onboard EarthCARE, in atmospheric monitoring, particularly in data-sparse regions where ground instrumentation is limited. Full article

Oxygenated volatile organic compounds (OVOCs) are key precursors to atmospheric ozone (O₃) and secondary organic aerosols (SOA). However, research on the sources of OVOCs is still limited, particularly in terms of multi-point observations at urban sites. This study conducted a one month continuous enhanced observation at an urban site (BA) and a suburban site (DP) in December 2024. During the study period, the average total VOCs concentration at the BA site was 29.9 ± 6.5 ppbv, significantly higher than that at the DP site (6.4 ± 1.3 ppbv). To enhance the representation of the biogenic fraction in OVOCs, isoprene was employed as a biogenic tracer; prior to source apportionment, its anthropogenic components were subtracted based on local emission ratio coefficients, thereby providing a more representative basis for biogenic source attribution. The optimized source apportionment results show that the contribution ratio of biogenic sources had decreased significantly, with a particularly noticeable decline at the urban site. Among these, the contribution rates of acetaldehyde and acetone had decreased significantly: by 14.7% and 12.2%, respectively. Based on the improved source apportionment method, the source apportionment of OVOCs at the urban site showed that methanol, acetone, and MEK were primarily dominated by anthropogenic primary sources (accounting for 44.5% to 68.5%), while acetaldehyde was primarily dominated by secondary anthropogenic generation (37.1%), indicating its key role as a photochemical product. In contrast, at the suburban site, the biogenic source contribution to acetaldehyde (37.8%) was significant. This difference highlights the necessity of optimizing biogenic source tracers and conducting OVOC source apportionment studies at multiple locations. Full article

Studying the vertical and horizontal distribution of particulate matter at the hectometer scale in the atmosphere is essential for understanding its sources, transportation, and transmission and its impact on human health. In this study, a method was developed based on hyperspectral instrumentation to obtain both vertical and horizontal distributions of aerosol extinction by employing multiple azimuth angles, selecting optimized elevation angles, and reducing the acquisition time of individual spectra. This method employed observations from different azimuth angles to represent particulate matter concentrations in various directions. The correlation coefficient between the hyperspectral observations and in-situ measurement was 0.627. Observations indicated that the aerosol extinction profile followed an exponential decay, with most aerosols confined below 1 km, implying a likely origin from local near-surface emissions. The horizontal distribution indicated that the northeastern urban areas and the eastern rural areas were the primary regions with high concentrations of particulate matter. The observational evidence suggests the presence of two potential emission sources within the study area. Moreover, health risk results indicated that even within the same town, differences of particulate matter concentration and population density could lead to varying health exposure risks. For instance, in the 200° and 210° directions, which represent adjacent urban areas less than 1 km apart, the number of PM_2.5-related illness cases in the 210° direction was 20.83% higher than that in the 200° direction. Full article

Despite increasing evidence that cigarette smoke is a significant source of indoor fine particulate matter (PM_2.5), quantitative emission factors (EFs) for PM_2.5 and its toxic chemical composition in mainstream (MS) and sidestream (SS) smoke are still not well defined. In this study, we employed a custom-designed chamber to separately collect MS (intermittent puff) and SS (continuous sampling) smoke from eleven cigarette models, representing six brands and two product types, under controlled conditions. PM_2.5 was collected on quartz-fiber filters and analyzed for carbon fractions (using the thermal–optical IMPROVE-A protocol), nine water-soluble inorganic ions (by ion chromatography), and twelve trace elements (via ICP-MS). SS smoke exhibited significantly higher mass fractions of total analyzed species (84.7% vs. 65.9%), carbon components (50.6% vs. 44.2%), water-soluble ions (17.1% vs. 13.7%), and elements (17.0% vs. 7.0%) compared to MS smoke. MS smoke is characterized by a high proportion of pyrolytic organic carbon fractions (OC₁–OC₃) and specific elements such as vanadium (V) and arsenic (As), while SS smoke shows elevated levels of elemental carbon (EC1), water-soluble ions (NH₄⁺, NO₃⁻), and certain elements like zinc (Zn) and cadmium (Cd). The toxicity-weighted distribution indicates that MS smoke primarily induces membrane disruption and pulmonary inflammation through semi-volatile organics and elements, whereas SS smoke enhances oxidative stress and cardiopulmonary impairment via EC-mediated reactions and secondary aerosol formation. The mean OC/EC ratio of 132.4 in SS smoke is an order of magnitude higher than values reported for biomass or fossil-fuel combustion, indicative of extensive incomplete combustion unique to cigarettes and suggesting a high potential for oxidative stress generation. Emission factors (µg/g cigarette) revealed marked differences: MS delivered higher absolute EFs for PM_2.5 (422.1), OC (8.8), EC (5.0), Na⁺ (32.6), and V (29.2), while SS emitted greater proportions of NH₄⁺, NO₃⁻, Cl⁻, and carcinogenic metals (As, Cd, Zn). These findings provide quantitative source profiles suitable for receptor-oriented indoor source-apportionment models and offer toxicological evidence to support the prioritization of comprehensive smoke-free regulations. Full article

In this study, typical haze pollution influenced by biomass burning (BB) activities in Changsha in the autumn of 2024 was investigated through the mixing state and evolution process of BB particles via the real-time measurement of single-particle aerosol mass spectrometry (SPAMS). From the clean period to the haze period, the PM_2.5 concentration increased from 25 μg·m⁻³ at 12:00 to 273 μg·m⁻³ at 21:00 on 12 October, and the proportion of total BB single particles in the total detected particles increased from 17.2% to 54%. This indicates that the rapid increase in PM_2.5 concentration was accompanied by a concurrent increase in the contribution of particles originating from BB sources. The detected BB particles were classified into two types based on their mixing states and temporal variations: BB1 and BB2, which accounted for 71.7% and 28.3% of the total BB particles, respectively. The analysis of backward trajectories and fire spots suggested that BB1 particles originated from straw burning emissions at northern Changsha, while BB2 particles were primarily related to local nighttime cooking emissions in Changsha. In addition, a special type of K-containing single particles without K cluster ions was found closely associated with BB1 type particles, which were designated as secondarily processed BB particles (BB-sec). The BB-sec particles contained abundant sulfate and ammonium signals and showed lagged appearance after the peak of BB1-type particles, which was possibly due to the aging and formation of ammonium sulfate on the freshly emitted particles. In all, this study provides insights into understanding the substantial impact of BB sources on regional air quality during the crop harvest season and the appropriate disposal of crop straw, including conversion into high-efficiency fuel through secondary processing or clean energy via biological fermentation, which is of great significance for the mitigation of local haze pollution. Full article

Atmospheric aerosols are recognized as a major air pollutant with significant impacts on human health, air quality, and climate. Yet, the chemical composition and seasonal variability of aerosols remain underexplored in several Western Mediterranean regions. This study presents a year-long investigation of PM_2.5 and PM₁₀ in Tetouan, Northern Morocco, where both local emissions and regional transport influence air quality. PM_2.5 and PM₁₀ samples were collected and analysed for total mass and comprehensive chemical characterization, including organic carbon (OC), elemental carbon (EC), water-soluble ions (WSIs), and sugar tracers (levoglucosan, arabitol, and glucose). Concentration-weighted trajectory (CWT) modelling and air mass back-trajectory analyses were used to assess potential source regions and transport pathways. PM_2.5 concentrations ranged from 4.2 to 41.8 µg m⁻³ (annual mean: 18.0 ± 6.4 µg m⁻³), while PM₁₀ ranged from 11.9 to 66.3 µg m⁻³ (annual mean: 30.8 ± 9.7 µg m⁻³), with peaks in winter and minima in spring. The PM_2.5-to-PM₁₀ ratio averaged 0.59, indicating a substantial accumulation of particle mass within the fine fraction, especially during the cold season. Carbonaceous aerosols dominated the fine fraction, with total carbonaceous aerosol (TCA) contributing ~52% to PM_2.5 and ~34% to PM₁₀. Secondary organic carbon (SOC) accounted for up to 90% of OC in PM_2.5, reaching 7.3 ± 3.4 µg m⁻³ in winter. WSIs comprised ~39% of PM_2.5 mass, with sulfate, nitrate, and ammonium as major components, peaking in summer. Sugar tracers exhibited coarse-mode dominance, reflecting biomass burning and biogenic activity. Concentration-weighted trajectory and back-trajectory analyses identified the Mediterranean Basin and Iberian Peninsula as dominant source regions, in addition to local urban emissions. Overall, this study attempts to fill a critical knowledge gap in Southwestern Mediterranean aerosol research by providing a comprehensive characterization of PM_2.5 and PM₁₀ chemical composition and their seasonal dynamics in Tetouan. It further offers new insights into how a combination of local emissions and regional transport shapes the aerosol composition in this North African urban environment. Full article

Exposure to microorganisms can significantly impact well-being and, more importantly, human health. A frequently overlooked aspect of indoor air quality (IAQ) research is the risk posed by harmful biological agents transported through the air in the form of biological aerosols. Given that healthcare facilities create environments with an increased risk of infection transmission, monitoring IAQ and reducing microbiological contamination have become global public health challenges. This paper presents a literature review, focusing on the current state of knowledge regarding microbiological air quality in healthcare settings. The analysis confirms that Escherichia coli and Staphylococcus aureus are among the most prevalent airborne pathogens in healthcare facilities. The review also underlines the necessity for harmonized guidelines and integrated air quality management strategies to reduce microbial contamination effectively. Finally, the review compiles data on microorganism concentration levels and influencing factors. The present study highlights that implementing standardized monitoring and effective air filtration and disinfection methods is essential to improving microbiological air quality and enhancing patient safety. The sources analyzed in this review were collected from databases such as PubMed, ScienceDirect, ResearchGate, and Web of Science, considering only English-language publications. The studies cited were conducted in multiple countries across different regions, providing a comprehensive global perspective on the issue. Full article

This study advances the understanding of atmospheric microplastic (MPs) exposure across urban (US), suburban (SS), and rural (RS) areas of Madrid, Spain, for the first time. Air pollution from MPs remains an understudied issue with broad implications for environmental and human health. Recent evidence highlights the need for multipoint studies to accurately establish atmospheric exposure to MPs, especially during winter seasons in the city. To address this issue, this work conducted active sampling of ≤10 μm aerosol particles, following EN 12341:2014 standards, during the 2024–2025 winter season. A quantitative innovative method using UV-assisted optical microscopy was applied to assess daily MPs exposure. To trace the potential sources and transport pathways, air mass back trajectories were modelled using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) software. The results showed an average exposure (n = 4) of 80 ± 20; 55 ± 9 and 46 ± 20 MPs·m⁻³·day⁻¹ during the sampling period in US, SS, and RS, respectively; and an average exposure (n = 4) of 61 ± 11 MPs·m⁻³·day⁻¹ throughout the winter period between November and December 2024 and January and February 2025. The polymers detected as constituents of MPs were polystyrene, polyethylene, polymethyl methacrylate, and polyethylene terephthalate, achieving a correct identification ratio of 100% for the detected microplastic particles. The HYSPLIT results showed diffuse sources of MPs, especially local, regional, and oceanic sources, in the US. In contrast, microplastic contributions in SS and RS areas originated from local or regional sources, highlighting the need for advanced studies to identify the sources of emissions and transport routes that converge in the occurrence of microplastics in the areas studied. These results demonstrate the atmospheric exposure to microplastics in the city, justifying the need for specialized studies to define the health impacts associated with the inhalation of these emerging pollutants. The findings of this research provide clear evidence of exposure to atmospheric microplastics in urban, suburban, and rural environments in Madrid, suggesting the need for further specialized research to rigorously assess the potential risks to human health associated with microplastic inhalation by the city’s population. Full article

Carbonaceous aerosols exert significant impacts on human health and climate systems. This study investigates the seasonal variations of carbonaceous components in fine particulate matter (PM_2.5) in Qinhuangdao, a coastal city in northern China, throughout 2023. The mass concentrations of organic carbon (OC) and elemental carbon (EC) averaged 9.44 ± 4.57 μg m⁻³ and 0.84 ± 0.33 μg m⁻³, contributing 26.49 ± 8.74% and 2.81 ± 1.56% to total PM_2.5, respectively. OC exhibited a distinct seasonal trend: winter (12.02 μg m⁻³) > spring (11.96 μg m⁻³) > autumn (8.15 μg m⁻³) > summer (5.71 μg m⁻³), whereas EC followed winter (1.31 μg m⁻³) > autumn (0.73 μg m⁻³) > spring (0.70 μg m⁻³) > summer (0.63 μg m⁻³). Both OC and EC levels were elevated at night compared to daytime. Secondary organic carbon (SOC), estimated via the EC-tractor method, constituted 37.94 ± 14.26% of total OC. A positive correlation between SOC/OC ratios and PM_2.5 concentrations suggests that SOC formation critically influences haze events. In autumn and winter, SOC formation was higher at night, likely driven by aqueous-phase reactions, whereas in summer SOC formation was more pronounced during the day, likely due to enhanced photochemical reactions. Source apportionment analysis revealed that gasoline and diesel vehicles were major contributors to carbonaceous aerosols, accounting for 27.35–29.06% and 14.97–31.83%, respectively. Coal combustion contributed less (10.51–21.55%), potentially due to strict regulations prohibiting raw coal use for domestic heating in surrounding regions. Additionally, fugitive dust was found to have a high contribution to carbonaceous aerosols during spring and summer. Full article

Gaseous pollutants and aerosols resulting from anthropic activities and natural phenomena require adequate source apportionment methodologies to be fully assessed. Furthermore, it is crucial to differentiate between fresh anthropogenic emissions and the atmospheric background. The proximity method based on the O₃/NO_x (ozone to nitrogen oxides) ratio has been used at the Lamezia Terme (code: LMT) World Meteorological Organization—Global Atmosphere Watch (WMO/GAW) regional station in Italy to determine the variability of CO (carbon monoxide), CO₂ (carbon dioxide), CH₄ (methane), SO₂ (sulfur dioxide), and eBC (equivalent black carbon), thus allowing the differentiation between local and remote sources of emission. Prior to this work, all O₃/NO_x ratios lower than 10 were grouped under the LOC (local) proximity category, thus including very low ratios (≤1), which are generally attributed by the literature to “urban” air masses, particularly enriched in anthropogenic emissions. This study, aimed at nine continuous years of measurements (2015–2023), introduces the URB category in the assessment of CO, CO₂, CH₄, SO₂, and eBC variability at the LMT site, highlighting patterns and peaks in concentrations that were previously neglected. The daily cycle, which is locally influenced by wind circulation and Planetary Boundary Layer (PBL) dynamics, is particularly susceptible to urban-scale emissions and its analysis has allowed the highlighting of notable peaks in concentrations that were previously neglected. Correlations with wind corridors and speeds indicate that most evaluated parameters are linked to northeastern winds at LMT and wind speeds under 5.5 m/s. Weekly cycle analyses, i.e., differences between weekdays (MON-FRI) and weekends (SAT-SUN), have also highlighted tendencies driven by seasonality and wind corridors. The results highlight the potential of the URB category as a tool necessary to access a given area’s anthropogenic output and its impact on air quality and the environment. Full article

The measurement and evaluation of the atmospheric background levels of greenhouse gases (GHGs) and aerosols are useful to determine long-term tendencies and variabilities, and pinpoint peaks attributable to anthropogenic emissions and exceptional natural emissions such as volcanoes. At the Lamezia Terme (code: LMT) World Meteorological Organization–Global Atmosphere Watch (WMO/GAW) observation site located in the south Italian region of Calabria, the “Proximity” methodology based on photochemical processes, i.e., the ratio of tropospheric ozone (O₃) to nitrogen oxides (NO_x) has been used to discriminate the local and remote atmospheric concentrations of GHGs. Local air masses are heavily affected by anthropogenic emissions while remote air masses are more representative of atmospheric background conditions. This study applies, to eight continuous years of measurements (2016–2023), the Proximity methodology to sulfur dioxide (SO₂) for the first time, and also extends it to equivalent black carbon (eBC) to assess whether the methodology can be applied to aerosols. The results indicate that SO₂ follows a peculiar pattern, with LOC (local) and BKG (background) levels being generally lower than their N–SRC (near source) and R–SRC (remote source), thus corroborating previous hypotheses on SO₂ variability at LMT by which the Aeolian Arc of volcanoes and maritime traffic could be responsible for these concentration levels. The anomalous behavior of SO₂ was assessed using the Proximity Progression Factor (PPF) introduced in this study, which provides a value representative of changes from local to background concentrations. This finding, combined with an evaluation of known sources on a regional scale, has been used to provide an estimate on the spatial resolution of proximity categories, which is one of the known limitations of this methodology. Furthermore, the results confirm the potential of using the Proximity methodology for aerosols, as eBC shows a pattern consistent with local sources of emissions, such as wildfires and other forms of biomass burning, being responsible for the observed peaks. Full article

Aerosol radiative forcing is known to significantly disturb the thermodynamic and dynamic structure of the Planetary Boundary Layer (PBL), particularly in heavily polluted urban regions. In this study, the effects of aerosol–PBL interactions were examined over a megacity in China’s Central Plains by comparing ERA5 reanalysis data with multi-source ground-based observations. Key meteorological variables—including wind speed, wind direction, temperature, and relative humidity—were analyzed across pressure levels from 1000 to 800 hPa. Good agreement in wind direction was observed between ERA5 and observations (R² > 0.84), while wind speed showed a moderate correlation (R² = 0.54–0.73) with an RMSE of 1.85 m/s near 975 hPa. Temperature discrepancies were found to decrease with altitude, with RMSE values reducing from 3.02 K to 1.84 K, indicating a modulation of thermal stratification by aerosol radiative effects. A stable structure was revealed by humidity analysis near the surface but increased variability aloft, with absolute differences reaching ±30% at 850–800 hPa. Diurnal variations were characterized by night-time warming of up to +5 °C in the lower PBL and concurrent cooling above 800 hPa. The Heating and surface Dimming (HD) Index was found to correlate positively with PM_2.5 concentration (R = 0.60), reflecting increased thermal stability and vertical inhomogeneity under aerosol loading. These findings underscore the need for an improved understanding and mitigation of aerosol–PBL interactions to support sustainable urban air quality management strategies. Full article

This study investigates the effects of key atmospheric features on mineral dust emissions and transport in the Sahara–Sahel region, focusing on the Bodélé Depression, during June 2006 and 2011. We use a combination of high-resolution atmospheric simulations (AROME model), satellite observations (MODIS), and reanalysis data (ERA5, ECMWF) to examine the roles of the low-level jet (LLJ), Saharan heat low (SHL), Intertropical Discontinuity (ITD), and African Easterly Jet (AEJ) in modulating dust activity. Our results reveal significant interannual variability in aerosol optical depth (AOD) between the two periods, with a marked decrease in June 2011 compared to June 2006. The LLJ emerges as a dominant factor in dust uplift over Bodélé, with its intensity strongly influenced by local topography, particularly the Tibesti Massif. The position and intensity of the SHL also play crucial roles, affecting the configuration of monsoon flow and Harmattan winds. Analysis of wind patterns shows a strong negative correlation between AOD and meridional wind in the Bodélé region, while zonal wind analysis emphasizes the importance of the AEJ and Tropical Easterly Jet (TEJ) in dust transport. Surprisingly, we observe no significant correlation between ITD position and AOD measurements, highlighting the complexity of dust emission processes. This study is the first to combine climatological context and case studies to demonstrate the effects of African monsoon variability on dust uplift at intra-seasonal timescales, associated with the modulation of ITD latitude position, SHL, LLJ, and AEJ. Our findings contribute to understanding the complex relationships between large-scale atmospheric features and dust dynamics in this key source region, with implications for improving dust forecasting and climate modeling efforts. Full article