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Based on long-term study in the Kara Sea basin (11 expeditions in 2007–2022), we, for the first time, statistically generalize atmospheric aerosol characteristics: the volume concentrations of submicron and coarse aerosol (Vf and Vс), the black carbon concentrations (еВС), and the spectral aerosol optical depth (AOD) of the atmosphere. High concentrations of submicron and absorbing (eBC) aerosol are pronounced in the average spatial distribution in the southwestern part of the Kara Sea, and they are minimal in the northern part. The difference in the average Vf and еВС between these regions is 30–60%. The average aerosol characteristics for the entire Kara Sea are: the atmospheric AOD (0.5 μm) is 0.043 with an Ångström exponent of 0.8, еВС = 22.8 ng/m3, Vf = 0.26 μm3/cm3, and Vс = 1.39 μm3/cm3. The average Vf and еВС over the Kara Sea are shown to be intermediate between the values for the Cape Baranov and the Barents Sea. [ABSTRACT FROM AUTHOR]

Lichens are not only a bioindicator of air pollution; they also affect the chemical composition of air. The qualitative composition of exometabolites in thalli of epiphytic lichens is studied using high-performance liquid chromatography. The comparative analysis of the fractional composition of deposited aerosol matter in water washouts of lichens shows it to be characterized by a bimodal particle distribution. It is postulated that the appearance of the fine fraction is associated with the generation of secondary organic aerosols on the surface of epiphytic lichens. Their precursors are the products of photoactivated reactions between deposited aerosol matter and highly volatile organic compounds which arrive on the lichen surface as a result of efflorescence. The mechanism of entry of secondary organic aerosols into the surface air layer under the radiometric photophoresis effect is discussed. [ABSTRACT FROM AUTHOR]

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NASA's Deep Blue aerosol project has developed global aerosol data records using consistent retrieval algorithms applied to various satellite sensors. The primary components of these data records are derived from the series of Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar‐orbiting Partnership (SNPP) and the National Oceanic and Atmospheric Administration or NOAA‐20+ satellites as well as the Moderate Resolution Imaging Spectroradiometer (MODIS), among others. These instruments provide over 23 years of measurements with similar radiometric characteristics for aerosol retrievals. The algorithms used for the initial Version 1 SNPP VIIRS data set were based on the MODIS Collection 6.1 Deep Blue algorithm over land and Satellite Ocean Aerosol Retrieval (SOAR) algorithm over water. For VIIRS Version 2 data reprocessing, major updates have been made to the algorithm suite, including better accounting for effects of surface pressure, improved determination of surface reflectance, and the inclusion of fine‐mode aerosol optical models to better represent anthropogenic aerosols over land. Cross‐calibration gain factors are derived for the NOAA‐20 VIIRS measurements to be consistent with the SNPP VIIRS, which allows the use of a unified algorithm package for both instruments. Comparisons against AERONET observations indicate that the Version 2 AOD data from SNPP VIIRS are significantly better than the Version 1 counterpart over land and slightly degraded over water in exchange for better spatial coverage. The AOD data from SNPP and NOAA‐20 VIIRS are comparable, indicating that cross‐calibration enables the creation of consistent aerosol data records using the series of VIIRS sensors. Plain Language Summary: Aerosols are tiny particles suspended in the air that can come from natural sources like dust and sea salt, as well as human activities such as burning fossil fuels and industrial processes. Understanding these particles are important because they play a crucial role in the Earth's system through interactions with sunlight, clouds, and precipitation. These interactions are in turn closely related to global warming and cooling effects. Additionally, certain types of aerosols can harm human health when inhaled, leading to respiratory problems. Because of these important aspects, scientists have developed various tools to study aerosols. Satellite remote sensing is one such tool and have provided valuable data on global aerosol properties. This study describes updates made to a satellite remote sensing technique to enhance data quality. The new data sets are significantly improved compared to previous versions, indicating increased utility of the data sets. Key Points: Introducing NASA's VIIRS Version 2 Deep Blue aerosol productsMajor updates in Deep Blue algorithm resulting in significant improvements in global aerosol optical depth retrievalsConsistent data records between SNPP and NOAA‐20+ VIIRS ensuring long‐term data continuity [ABSTRACT FROM AUTHOR]

[Display omitted] The smallest nanodrop tractable with macroscopic notions such as the interfacial energy could be determined by comparing heterogeneous nucleation observations and capillary theory predictions at decreasing drop diameters d p. This is done here for the condensation of n -butanol vapors on polyethylene glycol nano-globules (3 nm ≤ d p ≤ 9 nm). We use published activation probability measurements P(w,d p), where w is the accurately controlled saturation ratio of n -butanol vapor in a gas stream exiting a saturator. The maximal saturation ratio achieved in the nucleation region by cooling this gas-vapor stream in the apparatus of Gallar et al. satisfies S max = Cw. The key unknown constant C and the preexponential term K governing the nucleation rate are determined by assuming that classical theory applies to the largest particles used. This yields P(S max ,d p) data, directly comparable with capillary theory with perfect wetting. Excellent agreement is found above 5 nm for the critical dependence S max (d p) resulting from the constraint P(S max ,d p) = 0.5. The entire P(S max ,d p) curves also agree closely between 5 and 7 nm. Smaller particles depart only slightly from theory, even at d p = 3 nm. Capillary theory hence describes accurately the heterogeneous nucleation process above 3–5 nm, provides a reliable method to determine S max , and yields experimentally the nucleation rate constant K. [ABSTRACT FROM AUTHOR]

The discovery of smoke‐induced dynamical anomalies in the stratosphere associated with the 2019/2020 Australian New Year pyrocumulonimbus (pyroCb) super outbreak initiated a new field of study involving aerosol/weather anomalies. This paper documents the dynamical anomalies associated with the February 2009 Australian Black Saturday pyroCb outbreak. Positive potential vorticity anomalies (indicating anticyclonic rotation) with horizontal extent ∼1000 km and vertical thickness ∼2 km are associated with the plume, which we classify as a Smoke With Induced Rotation and Lofting (SWIRL). The SWIRL initially formed east of Australia, but then moved westward, crossing over Australia, and continuing to Africa. The SWIRL lasted for nearly three weeks (13 February–4 March), traveling ∼27,000 km and rising from potential temperatures of ∼410–500 K (altitudes ∼18–21 km). The altitude of the SWIRL is corroborated with coincident satellite‐based profiles of H2O, CO, HCN, O3, and aerosol extinction. A vertical temperature dipole (±3 K) accompanied the PV anomaly, as verified with coincident Global Navigation Satellite System radio occultation temperatures. The SWIRL dissipated as it passed over Africa. Operational ECMWF forecasts with early initialization (13 February) and late initialization (21 February) are examined. In the early case, the forecasted PV anomaly disappeared within 4 days, as expected due to lack of smoke heating in the forecast model. In the late case, while the forecasted PV anomaly was weaker than in the reanalyzes, a remnant anomaly remained out to 10 days. Plain Language Summary: Large bushfires in February 2009 in Australia led to large thunderstorms called pyrocumulonimbus (pyroCb) that injected significant amounts of smoke high into the atmosphere. When this smoke was warmed by absorbing sunlight it became buoyant and started to rise and rotate. This feature has been named a Smoke With Induced Rotation and Lofting (SWIRL) and had previously been observed in large pyroCbs that occurred around New Year's Day 2020 and in Canadian fires that occurred in 2017. The February 2009 SWIRL was a pancake‐like structure 1000 km across and 2 km thick. It lasted for three weeks, traveling over 27,000 km, and rising from 18 to 21 km in altitude. The SWIRL was observed both in weather maps and in satellite observations of gases such as water vapor, carbon monoxide, and ozone. Forecasting the SWIRL is difficult because current numerical weather models either do not consider smoke heating or lack inputs of pyroCb events as they are occurring in real time. Key Points: The February 2009 Australian Black Saturday pyroCbs injected a smoke plume into the stratosphere that induced a mesoscale anticycloneThe anticyclone was 1000 km across and 2 km thick and traveled 27,000 km in three weeks as it rose from 18 to 21 km in altitudeSatellite trace gas and aerosol anomalies coincide with potential vorticity anomalies, confirming smoke‐induced dynamical perturbations [ABSTRACT FROM AUTHOR]

Marine regulations aim to reduce sulfur and nitrogen exhaust emissions from maritime shipping. Here, two compliance pathways for reducing sulfur dioxide emissions, fuel sulfur content reduction and exhaust wet scrubbing, are studied for their effects on physicochemical properties and cloud forming abilities of engine exhaust particles. A test‐bed diesel engine was utilized to study fresh exhaust emissions from combustion of non‐compliant, high sulfur content fuel with (WS) and without (HiS) the usage of a wet scrubber as well as a regulatory compliant, low sulfur content fuel (LoS). Particle number emissions are decreased by ≈99% when switching to LoS due to absence of 20–30 nm sulfate rich particles. While number emissions for WS are also decreased, a shift in the sulfate mode toward larger sizes was found to increase particle mass emission factors by at least 31%. Changes in the mixing state induced by the compliance measures are reflected in the hygroscopicity of the exhaust particles. Fuel sulfur reduction decreased cloud condensation nuclei emissions by at least 97% due to emissions of primarily hydrophobic soot particles. Wet scrubbing increased those emissions, mainly driven by changes in particle size distributions. Our results indicate that both compliance alternatives have no obvious impact on the ice forming abilities of 200 nm exhaust particles. These detailed results are relevant for atmospheric processes and might be useful input parameters for cloud‐resolving models to investigate ship aerosol‐cloud interactions and to quantify the impact of shipping on radiative budgets from local to global scales. Plain Language Summary: We investigate how two pathways to comply with international regulations, aiming to reduce emissions of atmospheric pollutants from ships, alter properties of exhaust particles. Both investigated compliance measures (i.e., combustion of cleaner, low sulfur content fuels and aftertreatment of exhaust from a high sulfur content fuel via wet scrubbing) have substantial impacts on the chemical and physical properties of these particles. We find that, while both alternatives reduce the total number of emitted particles substantially, the effect on emissions of cloud forming particles is path dependent. While fuel sulfur content reduction decreased the number of cloud forming particles by about 97%, wet scrubbing led to a strong increase in emissions, suggesting that the measures can have substantial and opposing impacts on local cloud formation and evolution. Key Points: Low sulfur content fuels can reduce emissions of ultrafine particulate matter significantlyExhaust wet scrubbing can lead to shifts in particle size distributions and reduce soot emissionsUsage of low sulfur content fuels or exhaust wet scrubbing have opposing effects on CCN activity of ship exhaust particles [ABSTRACT FROM AUTHOR]

Initially, basic equations are given to express the activity concentrations and concentrations of potential α-energies of radon (222Rn) and thoron (220Tn) and their short-lived products in indoor air. The appearance of short-lived products as a radioactive aerosol is shown, and the fraction of the unattached products is particularly exposed, a key datum in radon dosimetry. This fundamental part is followed by giving the sources of radon and thoron indoors, and thus, their products, and displaying the dependence of their levels on the ground characteristics, building material and practice, and living–working habits of residents. Substantial hourly, daily, and seasonal changes in their activity concentrations are reviewed, as influenced by meteorological parameters (air temperature, pressure, humidity, and wind speed) and human activity (either by ventilation, air conditioning and air filtration, or by generating aerosol particles). The role of the aerosol particle concentration and their size distribution in the dynamics of radon products in indoor air has been elucidated, focusing on the fraction of unattached products. Intensifying combined monitoring of radon short-lived products and background aerosol would improve radon dosimetry approaches in field and laboratory experiments. A profound knowledge of the influence of meteorological parameters and human activities on the dynamics of the behaviour of radon and thoron accompanied by their products in the air is a prerequisite to managing sustainable indoor air quality and human health. [ABSTRACT FROM AUTHOR]

Above-water radiometry (AWR) methods have been developed to provide "ground-truth" (or fiducial) measurements for calibration and validation of the water color satellite missions. AWR is also an important tool for environmental survey from dedicated field missions. Under clear sky, the critical step of AWR is to retrieve the water-leaving radiance from radiometric measurements of the upward radiance that also includes the reflection of the direct sunlight and diffuse skylight reflected by the wind ruffled water surface toward the sensor. In order to correct for the surface reflection, sky radiance measurements are performed and converted into surface radiance through a factor often called "sea surface reflectance factor" or "effective Fresnel reflectance coefficient". Based on theoretical and practical considerations, this factor was renamed surface-to-sky radiance ratio, Rss, to avoid misuse of the term reflectance as often encountered in the literature. Vector radiative transfer computations were performed over the spectral range 350-1,000 nm to provide angular values of Rss for a comprehensive set of aerosol loads and types (including maritime, continental desert and polluted models) and water surface roughness expressed in wave slope variances or in equivalent Cox-Munk wind speeds, for practical use. After separating direct and diffuse light components, it was shown that the spectral shape and amplitude of Rss are very sensitive to aerosol load and type even for extremely low values of the aerosol optical thickness. Uncertainty attached to Rss was computed based on propagation of errors made in aerosol and surface roughness parameters demonstrating the need to adapt the viewing geometry according to the Sun elevation and to associate concurrent aerosol measurements for optimal AWR protocols. [ABSTRACT FROM AUTHOR]

Nebulizers are used commonly for inhaled drug delivery. Because they deliver medication through aerosol generation, clarification is needed on what constitutes safe aerosol delivery in infectious respiratory disease settings. The COVID-19 pandemic highlighted the importance of understanding the safety and potential risks of aerosol-generating procedures. However, evidence supporting the increased risk of disease transmission with nebulized treatments is inconclusive, and inconsistent guidelines and differing opinions have left uncertainty regarding their use. Many clinicians opt for alternative devices, but this practice could impact outcomes negatively, especially for patients who may not derive full treatment benefit from handheld inhalers. Therefore, it is prudent to develop strategies that can be used during nebulized treatment to minimize the emission of fugitive aerosols, these comprising bioaerosols exhaled by infected individuals and medical aerosols generated by the device that also may be contaminated. This is particularly relevant for patient care in the context of a highly transmissible virus. How can potential risks of infections during nebulization be mitigated? The COPD Foundation Nebulizer Consortium (CNC) was formed in 2020 to address uncertainties surrounding administration of nebulized medication. The CNC is an international, multidisciplinary collaboration of patient advocates, pulmonary physicians, critical care physicians, respiratory therapists, clinical scientists, and pharmacists from research centers, medical centers, professional societies, industry, and government agencies. The CNC developed this expert guidance to inform the safe use of nebulized therapies for patients and providers and to answer key questions surrounding medication delivery with nebulizers during pandemics or when exposure to common respiratory pathogens is anticipated. CNC members reviewed literature and guidelines regarding nebulization and developed two sets of guidance statements: one for the health care setting and one for the home environment. Future studies need to explore the risk of disease transmission with fugitive aerosols associated with different nebulizer types in real patient care situations and to evaluate the effectiveness of mitigation strategies. [ABSTRACT FROM AUTHOR]

In the context of global climate change, lightning disasters have emerged as a serious environmental factor that restricts the sustainable development of megacities. This paper provides a review of the research on the impact of urbanization on thunderstorm processes and lightning activity, exploring various aspects, such as aerosols, urban thermal effects, urban dynamic effects, and building morphology. Despite numerous significant achievements in the study of the impact of air pollutants on lightning activity, there is no consensus on whether aerosols serve to enhance or inhibit lightning activity. The temperature difference between the urban underlying surface and the natural underlying surface could sustain and promote the occurrence and development of convective systems, thus enhancing lightning activity. In terms of urban dynamics, the barrier effect has led to the maximum center of lightning appearing at the edge of a built-up area, which might be associated with factors, such as urban heat island (UHI) intensity, wind speed, synoptic background, and city size. Additionally, the size of a city and the height of the buildings was also an influencing factor on lightning activity. In summary, scholars have made progress in understanding the characteristics and drivers of urban lightning activity in recent years, but there are still some urgent problems that need to be solved: (1) How to analyze, comprehensively, the spatiotemporal patterns of urban lightning activity under different thunderstorm intensity backgrounds? (2) How to conduct analysis to investigate the influence of alterations in the boundary layer structure, water–heat energy balance, and water vapor circulation processes on urban lightning activity in the context of urbanization? (3) How to couple numerical models of different scales to enhance the understanding of the impact of complex underlying surfaces on urban lightning activity? Future studies could investigate the relationship between urbanization and thunderstorm/lightning activity using a combination of observational data, numerical modeling, and laboratory experiments, which holds promise for providing valuable theoretical insights and technical support to enhance the prediction, nowcasting, early warning, and risk assessment of thunderstorms and lightning in urban areas. [ABSTRACT FROM AUTHOR]

Ultraviolet radiation (UV) has strong chemical and biological effects on human health and ecosystems, and it plays an important role in the atmospheric environment by affecting photochemical processes, etc. Clouds and aerosols are the main factors affecting UV radiation and analyzing the quantitative impact of them on UV radiation is of great significance. Using the observation data of UV radiation in Beijing from 2005 to 2020, as well as the data of aerosol optical depth (AOD), single scattering albedo (SSA), and other related parameters, this paper simulated the surface UV radiation in two scenarios of cloudless without aerosol and cloudless with aerosol based on the TUV (Tropospheric Ultraviolet-Visible model), and quantitatively evaluated the attenuation of UV radiation by aerosol and cloud in the Beijing area. The results show that UV radiation is more sensitive to changes in AOD. Fixing the SSA value to 0.9, when the AOD increases from 0.2 to 1.0, the UV radiation decreases from 21.16 W/m2 to 12.64 W/m2 at 12:00; when AOD is maintained at 0.64, the SSA increases from 0.7 to 0.95, and the UV radiation increases from 14.55 W/m2 to 19.91 W/m2. The average annual attenuation rates of ultraviolet radiation by aerosols and clouds from 2005 to 2020 are 30.64% and 40.22%, respectively; the monthly averaged attenuation rates are 30.48% and 42.04%, respectively; and the daily averaged attenuation rates are 31.02% and 50.45%, respectively. [ABSTRACT FROM AUTHOR]

The aviation sector, like most other sectors, is moving towards becoming net zero. In the medium to long term, this will mean an increase in the use of sustainable aviation fuels. Research exists on the impact of fuel composition on non-volatile particulate matter (nvPM) emissions. However, there is more sparsity when considering the impact on volatile particulate matter (vPM) emissions. Here, nine different fuels were tested using an open-source design combustor rig. An aerosol mass spectrometer (AMS) was used to examine the mass-loading and composition of vPM, with a simple linear regression algorithm used to compare relative mass spectrum similarity. The diaromatic, cycloalkane and aromatic contents of the fuels were observed to correlate with the measured total number concentration and nvPM mass concentrations, resulting in an inverse correlation with increasing hydrogen content. The impacts of fuel properties on other physical properties within the combustion process and how they might impact the particulate matter (PM) are considered for future research. Unlike previous studies, fuel had a very limited impact on the organic aerosol's composition at the combustor exit measurement location. Using a novel combination of Positive Matrix Factorization (PMF) and high-resolution AMS analysis, new insight has been provided into the organic composition. Both the alkane organic aerosol (AlkOA) and quenched organic aerosol (QOA) factors contained CnH2n+1, CnH2n−1 and CnH2n ion series, implying alkanes and alkenes in both, and approximately 12% oxygenated species in the QOA factor. These results highlight the emerging differences in the vPM compositional data observed between combustor rigs and full engines. [ABSTRACT FROM AUTHOR]

The particles of micron and submicron sizes (PM 2.5 and less) in gas environments pose a significant danger to humanity due to the emergence of specific and very dangerous diseases of the cardiovascular, respiratory, and immune systems of the human body. Such particles are the most difficult to detect; therefore, their effects on human health have only been discovered in recent decades. Classical ultrasonic coagulation by sinusoidal action turns out to be ineffective for PM 2.5 due to the peculiarities of the physical mechanisms of hydrodynamic and orthokinetic interaction realized in gaseous media. This article presents a theoretical justification for choosing ways to increase the efficiency of ultrasonic coagulation of PM 2.5 by creating special conditions under which nonlinear disturbances of the velocity and pressure of the gas phase in the ultrasonic field occur. The authors performed simulations of ultrasonic coagulation under nonlinear disturbances of the velocity (vortex) and the pressure (shock waves), which has numerical difficulties due to the instability of existing methods. As a result of the numerical analysis, the possibility of increasing the coagulation rate of particles in the submicron size range up to limit values (13 times due to nonlinear pressure disturbances, and an additional increase of at least 2 times due to aerosol compaction in the vortex field of gas velocity) was shown. [ABSTRACT FROM AUTHOR]

Simple Summary: Elevating biosecurity in livestock housing is vital in ensuring the safety of animal products. In Japan, approximately 70% of post-weaning mortality is attributable to respiratory pathogens. Microorganisms, including viruses and bacteria, do not float independently but depend on aerosols for transmission. Hence, controlling aerosols is crucial in reducing pathogens and enhancing livestock production. This study aimed to decrease aerosol and microbial concentrations, along with airborne viruses, by employing ozone solution spraying. Experiments were conducted in an integrated management farm in Fukushima Prefecture, involving nanobubble ozone water sprayed with an ultrasonic sprayer. Results showed a substantial reduction in microbial concentrations and aerosol mass, indicating its effectiveness. Enhancing biosecurity measures in livestock is an essential prerequisite for producing animal products with the highest levels of safety and quality. In Japan, 70% of the mortalities post-weaning are attributed to respiratory pathogens. The research has shown that microorganisms, including both viruses and bacteria, do not merely float in the air independently. Instead, they spread by adhering to aerosols. Therefore, improving the control of aerosol dissemination becomes a critical strategy for reducing pathogenic loads and boosting the overall efficiency of livestock production. This study focused on reducing concentrations of aerosol particles, airborne microbial concentrations, and airborne mass concentrations by spraying ozone solution with an ultrasonic sprayer. The experiments were conducted at a farm in Fukushima Prefecture, Japan, known for its integrated management system, overseeing a herd of 200 sows. Nanobubble ozone water particles were dispersed using an ultrasonic sprayer, which allowed the particles to remain airborne significantly longer than those dispersed using a standard nozzle, at a rate of 30 mL per weaning pig 49 days old, for a 10 min period. This procedure was followed by a 10 min pause, and the cycle was repeated for 17 days. Measurements included concentrations of airborne bacteria, aerosol mass, and aerosol particles. The findings demonstrated a substantial reduction in airborne microbial concentrations of Escherichia coli and Staphylococcus aureus in the treated area compared to the control, with reductions reaching a peak of 85.7% for E. coli and 69.5% for S. aureus. Aerosol particle sizes ranging from 0.3–0.5 µm, 0.5–1.0 µm, 1.0–2.0 µm, 2.0–5.0 µm, to 5.0–10.0 µm were monitored, with a notable decrease in concentrations among larger particles. The average aerosol mass concentration in the test area was over 50% lower than in the control area. [ABSTRACT FROM AUTHOR]

China's severe particle pollution could affect the regional climate and weather conditions that consequently threaten local to global food security. Yet, the underlying mechanisms and quantitative assessment of aerosols on crop yields remain unknown. Here, by integrating a meteorology–chemistry model and a crop model, we show the impacts of atmospheric aerosols on China's meteorology and soybean yields. We find that the potential yields of soybean would decrease in most parts of China due to direct aerosol radiation effects, while showing diverse responses in parts of the Northeast and North China Plain. Moreover, because of the high sensitivity of soybean growth to water, potential yield fluctuations are closely related to aerosol‐induced precipitation changes in most soybean‐growing regions of China. In particular, aerosols play the most important role during soybean's pod‐filling stage, in which the influence of both precipitation perturbations and negative solar radiative forcing is about 5–10 times that of air temperature on crop yield. Our study thereby identifies aerosol mitigation can bring a notable increase in crop yields, highlighting the potential for important co‐benefits in food security across polluting developing countries. [ABSTRACT FROM AUTHOR]

Robust estimates of historical changes in aerosols are key for accurate constraints on climate sensitivity. Dry deposition is a primary sink of aerosols from the atmosphere. However, most global climate models do not accurately represent observed strong dependencies of dry deposition following turbulent transport on aerosol size. It is unclear whether there is a substantial impact of mischaracterized aerosol deposition velocities on historical aerosol changes. Here we describe improved mechanistic representation of aerosol dry deposition in the NASA Goddard Institute for Space Studies (GISS) global climate model, ModelE, and illustrate the impact on 1850–2000 changes in global aerosol burdens as well as aerosol direct and cloud albedo effects using a set of 1850 and 2000 time slice simulations. We employ two aerosol configurations of ModelE (a "bulk" mass‐based configuration and a configuration that more explicitly represents aerosol size distributions, internal mixing, and microphysics) to explore how model structural differences in aerosol representation alter the response to representation of dry deposition. Both configurations show larger historical increases in the global burdens of non‐dust aerosols with the new dry deposition scheme, by 11% in the simpler mass‐based configuration and 23% in the more complex microphysical configuration. Historical radiative forcing responses, which vary in magnitude from 5% to 12% as well as sign, depend on the aerosol configuration. Plain Language Summary: Numerical models representing the Earth system are important tools for understanding the drivers of climate change and variability. Particles (also known as aerosols) in the atmosphere can influence climate by scattering or absorbing solar radiation and influencing clouds. How the amount of particles in the atmosphere has changed since preindustrial times is very uncertain. Many processes impact particle spatial distributions and changes with time, as well as how particles influence climate. Sources and sinks of particles need to be represented well in order to have confidence in estimates of changes in particles. Here we more accurately simulate dry deposition, which is a sink of particles, in a numerical model that represents the Earth system, and examine impacts on changes in the amount of particles in the atmosphere from preindustrial times to present day and the particles' influence on climate. Key Points: ModelE now has process‐based representation of aerosol dry deposition, and captures strong observed dependencies on particle sizeIncreases from 1850 to 2000 in the global non‐dust aerosol annual burdens are 11%–23% larger with more mechanistic dry depositionHistorical radiative forcing responses (−12% to +6%) depend on aerosol representation (e.g., microphysics and mixing state) [ABSTRACT FROM AUTHOR]

Radioactive aerosols produced by nuclear accidents and decommissioning of nuclear power plants would cause tremendous radioactive damage to the environment and human body. The development of a radioactive aerosol suppressant is of great significance in the treatment of radioactive aerosols. In this study, a three-dimensional biomass-based polymer pectin-g-acrylic acid-acrylamide (pectin-g-poly (AA-co-AM)) SAP with high water absorbency and high agglomeration was prepared by solution polymerization. The results showed that the water absorbency of pectin grafted with acrylic acid and acrylamide reached 1064 g/g. Furthermore, under the synergistic effect of water absorption and agglomeration of the material, the sedimentation efficiency of simulated radioactive aerosol by 30 min after using suppressant is 91.21%. [ABSTRACT FROM AUTHOR]

Introduction: The selection of inhaler device is of critical importance in chronic obstructive pulmonary disease (COPD) as the interaction between a patient's inhalation profile and the aerosol characteristics of an inhaler can affect drug delivery and lung deposition. This study assessed the in vitro aerosol characteristics of inhaler devices approved for the treatment of COPD, including a soft mist inhaler (SMI), pressurized metered-dose inhalers (pMDIs), and dry powder inhalers (DPIs). Methods: High-speed video recording was used to visualize and measure aerosol velocity and spray duration for nine different inhalers (one SMI, three pMDIs, and five DPIs), each containing dual or triple fixed-dose combinations of long-acting muscarinic receptor antagonists and long-acting β2-agonists, with or without an inhaled corticosteroid. Measurements were taken in triplicate at experimental flow rates of 30, 60, and 90 l/min. Optimal flow rates were defined based on pharmacopoeial testing requirements: 30 l/min for pMDIs and SMIs, and the rate achieving a 4-kPa pressure drop against internal inhaler resistance for DPIs. Comparison of aerosol plumes was based on the experimental flow rates closest to the optimal flow rates. Results: The Respimat SMI had the slowest plume velocity (0.99 m/s) and longest spray duration (1447 ms) compared with pMDIs (velocity: 3.65–5.09 m/s; duration: 227–270 ms) and DPIs (velocity: 1.43–4.60 m/s; duration: 60–757 ms). With increasing flow rates, SMI aerosol duration was unaffected, but velocity increased (maximum 2.63 m/s), pMDI aerosol velocity and duration were unaffected, and DPI aerosol velocity tended to increase, with a more variable impact on duration. Conclusions: Aerosol characteristics (velocity and duration of aerosol plume) vary by inhaler type. Plume velocity was lower and spray duration longer for the SMI compared with pMDIs and DPIs. Increasing experimental flow rate was associated with faster plume velocity for DPIs and the SMI, with no or variable impact on plume duration, whereas pMDI aerosol velocity and duration were unaffected by increasing flow rate. [ABSTRACT FROM AUTHOR]

Nebulized therapy is the mainstay for treating obstructive airway diseases, but there is heightened concern about the potential risk for SARS-CoV-2 transmission during nebulization in COVID-19 patients. To investigate the effects of 0.9% saline nebulization on SARS-CoV-2 RNA spreading in 11 COVID-19 patients (five females, mean age 62.45 ± 9.31 years); also to ascertain whether saline nebulization changed the number of exhaled bio-aerosol particles in six out of the 11 patients. Air samples were collected using suction pumps equipped with 0.45 μm PTFE filters and positioned around the patient's bed. Exhaled particles were quantified by using an optical particle counter. At baseline (i.e. before nebulization) SARS-CoV-2 was detected more frequently in the pumps close to the patient than in those far away. After saline nebulization, the detection of SARS-CoV-2 in the pumps close to the patient was comparable to that observed at baseline. In the pumps far from the patient, saline nebulization slightly, but not significantly, increased SARS-CoV-2 RNA detection compared to baseline. Overall, no significant changes in the SARS-CoV-2 RNA detection were observed after saline nebulization. At baseline, exhaled particle emission varied among patients, with two of them showing higher emission of particles than the remaining patients. Saline nebulization induced a marked decrease in exhaled particles in the two patients who displayed high emission at baseline, whereas no changes were observed in the remaining patients. Saline nebulization did not significantly change SARS-CoV-2 RNA spreading. Saline nebulization does not significantly increase SARS-CoV-2 spreading. [ABSTRACT FROM AUTHOR]

To assess the aetiology, management and outcomes of cold burn injuries presenting to a regional burn unit in the United Kingdom. Retrospective cohort study of consecutive patients over a 5-year period (2018–2022). Sixty-two patients (M:F 34:38; median age 23.5 years) were identified. The most common aetiology was aerosol (n = 28, 45.2%). Seven (11.5%) injuries were sustained during a social media or peer 'challenge' and 19 (31.2%) were self-harm, of whom 5 (26.3%) were inpatients on a mental health ward at the time of injury. All 'challenge' and self-harm injuries were caused by aerosol. Patients with 'challenge' injury were younger than those with self-harm (p =.007) and non-intentional injuries (p <.001). A greater proportion of self-harm injuries were in female patients compared with non-intentional injuries (p <.001). Median total body surface area (TBSA) was 0.35% (IQR: 0.3). Most burns were superficial partial thickness (n = 35, 56.5%), followed by deep dermal (n = 18, 29.0%), full-thickness (n = 8, 12.9%), and superficial (n = 1, 1.6%). The upper limb was most frequently affected (n = 35, 56.5%). Aetiology and a non-intentional, 'challenge' or self-harm injury did not affect TBSA (p = 0.776 and p = 0.364) or depth (p = 0.353 and p = 0.381). Five (8.1%) patients underwent autografting. The median time to healing was 17 days (range: 7–45, IQR: 22.75). Follow-up ranged from 1 to 173 weeks. The incidence of cold burns has increased when compared with previous literature. A disproportionate number of cold burns are self-inflicted using aerosols, either as self-harm or because of social media or peer 'challenges'. Other emerging aetiologies include non-intentional skin contact with nitrous oxide containers during its recreational use. [ABSTRACT FROM AUTHOR]

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Biomass burning is one of the largest sources of particulate matter emissions globally. However, the emission of particulate inorganic species from prescribed grassland burning in Japan has not yet been characterized. In this study, we collected total suspended particulate matter from prescribed grassland burning in Hirado, Akiyoshidai, and Aso, Japan. The collected filter samples were brought to the laboratory, and water-soluble inorganic components were analyzed via ion chromatography. The measurement results showed high excess concentrations of potassium, calcium, and magnesium, and these substances were highly correlated, which agreed with previously reported findings. In contrast, the concentrations of sodium, chloride, nitrate, and sulfate were insignificant, even though their high concentrations were reported in other biomass burning studies. Among these low concentration substances, a high correlation was still observed between sulfate and nitrate. It is possible that the low concentrations of those species could have been biased in the measurements, particularly as a result of subtracting blank and background values from the observed concentrations. Building up more data in this area may allow us to characterize the significance of domestic biomass burning's contribution to inorganic particulate components in Japanese air, which may consequently contributes to better understanding of adverse health effect of airborne particulate matter. [ABSTRACT FROM AUTHOR]

Introduction: Climate change has had irreversible effects on the planet Earth. The impacts of these changes are observable in all natural and human phenomena. One of the affected phenomena by climate change is dust storms. Besides their short-term and long-term effects, these storms significantly influence air quality on both local and global scales. In recent decades, the frequency of dust storms has increased due to climate variations and human activities, and it is predicted that this increasing trend will continue in the future. Investigating the effects of climate change on dust storms in Southwest Asia, as one of the most significant dust storm hotspots globally, holds great importance. The objective of this research is to examine the impacts of climate change and forecast dust storms in Southwest Asia using the GRDL-ESM4 model from the CMIP6 model ensemble under the optimistic scenario (SSP1.2.6) during the near-future period (2021-2060). Materials and methods: Southwest Asia is located in the global desert belt. The intensification of climate change in this region has distinct impacts on the trends of dust storms, especially mineral dust storms. Therefore, this study focuses on forecasting dust storms in Southwest Asia using the CMIP6 model ensemble, specifically the GFDL-ESM4 model, under the optimistic scenario (SSP1-2.6). The research methodology involves initially using a 40-year historical period (1975-2014) to analyze dust storm anomalies. Then, the CMIP6 model ensemble, specifically the GRDL-ESM4 model, is utilized to examine the dust storm trends until the end of the present century. Furthermore, the optimistic scenario (SSP1-2.6) is employed for the near-future forecasting period (2021-2060). Results and discussion: The results show that the maximum amount of dust storms occurs during the summer and spring seasons. In the summer season, the significant increase in temperature and decrease in precipitation contribute to the highest level of dust storms. The spring season exhibits a high level of dust storms compared to other seasons, with northern latitudes having more dust storms than southern latitudes. The minimum dust storm occurrence is observed during the autumn and winter seasons. Autumn is characterized by decreasing temperatures and increasing precipitation processes, leading to a reduction in dust storm frequency. In the winter season, the semi-Arabian Peninsula, especially the eastern regions, experiences the highest dust storm occurrence. In the spring season, the eastern part of the Arabian Peninsula, during the summer season, the southeastern regions of the Arabian Peninsula and southeastern Iran, and during the autumn season, the northern half of Arabia and eastern Iran have the highest frequency of dust storms. According to the optimistic scenario, the summer and spring seasons have the highest dust storm occurrence. Furthermore, it is evident that the intensity of dust storm trends will be higher in the southeastern regions of the Arabian Peninsula, the Makran coasts, the northern half of Iran, northern Arabia, and between the rivers compared to other areas. Conclusion: In general, southern latitudes experience higher levels of dust storms compared to northern latitudes. The primary center of dust storms is located over the Arabian Peninsula in early winter, gradually shifting towards the eastern regions. During this season, the center of dust storms moves from eastern Arabia to southeastern parts of the Arabian Peninsula and southeastern Iran. [ABSTRACT FROM AUTHOR]

Emission of airborne particulate matter is produced by the industrial processes of metal extraction from electronic waste (e‐waste). These aerosols can transport organic contaminants, such as polyaromatic hydrocarbons (PAHs) and polybrominated biphenyls. These pollutants are proven to have long‐term effects on workers' health. In this work, we characterize aerosol particles and dust deposited from a recycling process of printed circuit boards in a recycling plant. This study also explores the significance of the secondary aerosol sources, and their importance, as an additional burden compared to primary sources. A Scanning Mobility Particles Counter and Sizer (SMPCS) was used to measure the size distributions of ultrafine particles. A Micro‐Orifice Uniform Deposition Impactor (MOUDI) collected aerosol particle samples for chemical analysis. All plant compartments checked are subject to high particulate matter concentrations during work hours. Concentrations of organic pollutants in the machinery compartments do not pose a short or long‐term health risk according to US Occupational Safety and Health Administration (OHSA). The application of the model presented in this work revealed that the accumulation of contaminants in other compartments should be considered in an occupational exposure assessment because it can present an equally important burden to workers' health. [ABSTRACT FROM AUTHOR]

This study examined long-term aerosol optical thickness (AOT) data from the Moderate Resolution Imaging Spectroradiometer (MODIS) to quantify aerosol conditions on the Korean Peninsula. Time-series machine learning (ML) techniques and spatial interpolation methods were used to predict future aerosol trends. This investigation utilized AOT data from Terra MODIS and meteorological data from Automatic Weather System (AWS) in eight selected cities in Korea (Gangneung, Seoul, Busan, Wonju, Naju, Jeonju, Jeju, and Baengyeong) to assess atmospheric aerosols from 2000 to 2021. A machine-learning-based AOT prediction model was developed to forecast future AOT using long-term observations. The accuracy analysis of the AOT prediction results revealed mean absolute error of 0.152 ± 0.15, mean squared error of 0.048 ± 0.016, bias of 0.002 ± 0.011, and root mean squared error of 0.216 ± 0.038, which are deemed satisfactory. By employing spatial interpolation, gridded AOT values within the observation area were generated based on the ML prediction results. This study effectively integrated the ML model with point-measured data and spatial interpolation for an extensive analysis of regional AOT across the Korean Peninsula. These findings have substantial implications for regional air pollution policies because they provide spatiotemporal AOT predictions. [ABSTRACT FROM AUTHOR]

Rapidly increasing urbanization in recent decades has elevated the subway as the primary public transportation mode in metropolitan areas. Indoor air quality (IAQ) inside subways is an important factor that influences the health of commuters and subway workers. This review discusses the subway IAQ in different cities worldwide by comparing the sources and abundance of particulate matter (PM2.5 and PM10) in these environments. Factors that affect PM concentration and chemical composition were found to be associated with the subway internal structure, train frequency, passenger volume, and geographical location. Special attention was paid to air pollutants, such as transition metals, volatile/semi-volatile organic compounds (VOCs and SVOCs), and bioaerosols, due to their potential roles in indoor chemistry and causing adverse health impacts. In addition, given that the IAQ of subway systems is a public health issue worldwide, we calculated the Gini coefficient of urban subway exposure via meta-analysis. A value of 0.56 showed a significant inequity among different cities. Developed regions with higher per capita income tend to have higher exposure. By reviewing the current advances and challenges in subway IAQ with a focus on indoor chemistry and health impacts, future research is proposed toward a sustainable urban transportation systems.

ABSTRACT: In recent years, a series of public health issues caused by the spread of antibiotic resistance have been widely concerned. The indoor air of livestock and poultry houses is considered to be one of the main sources of environmental contamination of ARGs. This study characterized the micro-organisms and ARGs in the air particulate matter of chicken houses using metagenomics. The study successfully detected 761 different subtypes of resistance genes including aminoglycosides, tetracyclines, MLSB etc., 4 types of mobile genetic elements, and various pathogenic microorganisms from the aerosols in the chicken coop environment. The results showed that the abundance of ARGs in the air of the chicken coop was at a relatively high level, correlation network analysis showed that multiple types of ARGs could promote the emergence of antibiotic-resistant bacteria.

Abstract Aerosol increases over the 20th century delayed the rate at which Earth warmed as a result of increases in greenhouse gases (GHGs). Aggressive aerosol mitigation policies arrested aerosol radiative forcing from ∼1980 to ∼2010. Recent evidence supports decreases in forcing magnitude since then. Using the approximate partial radiative perturbation (APRP) method, future shortwave aerosol effective radiative forcing changes are isolated from other shortwave changes in an 18‐member ensemble of ScenarioMIP projections from phase 6 of the Coupled Model Intercomparison Project (CMIP6). APRP‐derived near‐term (2020–2050) aerosol forcing trends are correlated with published model emulation values but are 30%–50% weaker. Differences are likely explained by location shifts of aerosol‐impacting emissions and their resultant influences on susceptible clouds. Despite weaker changes, implementation of aggressive aerosol cleanup policies will have a major impact on global warming rates over 2020–2050. APRP‐derived aerosol radiative forcings are used together with a forcing and impulse response model to estimate global temperature trends. Strong mitigation of GHGs, as in SSP1‐2.6, likely prevents warming exceeding 2C since preindustrial but the strong aerosol cleanup in this scenario increases the probability of exceeding 2C by 2050 from near zero without aerosol changes to 6% with cleanup. When the same aerosol forcing is applied to a more likely GHG forcing scenario (i.e., SSP2‐4.5), aggressive aerosol cleanup more than doubles the probability of reaching 2C by 2050 from 30% to 80%. It is thus critical to quantify and simulate the impacts of changes in aerosol radiative forcing over the next few decades.

The risk of Legionella transmission in built environments remains a significant concern. Legionella can spread within buildings through aerosol transmission, prompting the exploration of airborne transmission pathways and proposing corresponding prevention and control measures based on building characteristics. To this end, a comprehensive literature review on the transmission risk of Legionella in built environments was performed. Four electronic databases (PubMed, Web of Science, Google Scholar, and CNKI) were searched from inception to March 2024 for publications reporting the risk of Legionella transmission in built environments. Relevant articles and gray literature reports were hand-searched, and 96 studies were finally included. Legionella pollution comes from various sources, mainly originates in a variety of built environments in which human beings remain for extended periods. The sources, outbreaks, national standards, regulations, and monitoring techniques for Legionella in buildings are reviewed, in addition to increases in Legionella transmission risk due to poor maintenance of water systems and long-distance transmission events caused by aerosol characteristics. Air and water sampling using various analytical methods helps identify Legionella in the environment, recognize sources in the built environments, and control outbreaks. By comparing the standard regulations of national organizations globally, the authors further highlight gaps and deficiencies in Legionella surveillance in China. Such advancements offer essential insights and references for understanding and addressing Legionella transmission risk in the built environment, with the potential to contribute to safeguarding public health and building environment safety.

Airborne infection risk analysis is usually performed for enclosed spaces where susceptible individuals are exposed to infectious airborne respiratory droplets by inhalation. It is usually based on exponential, dose-response models of which a widely used variant is the Wells–Riley (WR) model. We revisit this infection-risk estimate and extend it to the population level. We use an epidemiological model where the mode of pathogen transmission, airborne or contact, is explicitly considered. We illustrate the link between epidemiological models and the WR and the Gammaitoni and Nucci models. We argue that airborne infection quanta are, up to an overall density, airborne infectious respiratory droplets modified by a parameter that depends on biological properties of the pathogen, physical properties of the droplet and behavioural properties of the individual. We calculate the time-dependent risk of being infected for two scenarios. We show how the epidemic infection risk depends on the viral latent period and the event time, the time infection occurs. Infection risk follows the dynamics of the infected population. As the latent period decreases, infection risk increases. The longer a susceptible is present in the epidemic, the higher its risk of infection for equal exposure time to the pathogen is.

Abstract Weekly cycles (WCs) in cloud properties have been reported and linked to aerosol effects. Yet the extent to which human activities contribute to their occurrence remains unclear. Here, we revisit aerosol–cloud interactions from the WCs over central Europe using long‐term satellite and reanalysis data. Significant WCs in aerosol and cloud droplet number concentration (Nd) are detected with minima/maxima on Monday/Friday, indicating a clear signal of the Twomey effect. Notably, Nd–to–aerosol sensitivity from WCs is found to decrease at larger aerosol concentrations, confirming the nonlinear behavior of the aerosol–Nd relation (in log–log space) reported previously, but from a distinct perspective. Nevertheless, no discernible WCs in liquid water path are found. The pronounced WCs in cloud cover are demonstrated to be driven by natural variability. Our results indicate that the WCs offer a useful pathway for investigating the Twomey effect, but are not as effective for detecting cloud adjustments.

In recent years, aerosols have been recognized as a prominent medium for the transmission of antibiotic-resistant bacteria and genes. Among these, particles with a particle size of 2 μm (PM2.5) can directly penetrate the alveoli. However, the presence of antibiotic-resistant genes in aerosols from pet hospitals and the potential risks posed by antibiotic-resistant bacteria in these aerosols to humans and animals need to be investigated. In this study, cefotaxime-resistant bacteria were collected from 5 representative pet hospitals in Changchun using a Six-Stage Andersen Cascade Impactor. The distribution of bacteria in each stage was analyzed, and bacteria from stage 5 and 6 were isolated and identified. Minimal inhibitory concentrations of isolates against 12 antimicrobials were determined using broth microdilution method. Quantitative Polymerase Chain Reaction was employed to detect resistance genes and mobile genetic elements that could facilitate resistance spread. The results indicated that ARBs were enriched in stage 5 (1.1–2.1 μm) and stage 3 (3.3–4.7 μm) of the sampler. A total of 159 isolates were collected from stage 5 and 6. Among these isolates, the genera Enterococcus spp. (51%), Staphylococcus spp. (19%), and Bacillus spp. (14%) were the most prevalent. The isolates exhibited the highest resistance to tetracycline and the lowest resistance to cefquinome. Furthermore, 56 (73%) isolates were multidrug-resistant. Quantitative PCR revealed the expression of 165 genes in these isolates, with mobile genetic elements showing the highest expression levels. In conclusion, PM2.5 from pet hospitals harbor a significant number of antibiotic-resistant bacteria and carry mobile genetic elements, posing a potential risk for alveolar infections and the dissemination of antibiotic resistance genes.

After the outbreak of COVID-19, additional protocols have been established to prevent the transmission of the SARS-CoV-2 from the patient to the health personnel and vice versa in health care settings. However, in the case of emergency surgeries, it is not always possible to ensure that the patient is not infected with SARS-CoV-2, assuming a potential source of transmission of the virus to health personnel. This work aimed to evaluate the presence of the SARS-CoV-2 and quantify the viral load in indoor air samples collected inside operating rooms, where emergency and scheduled operations take place. Samples were collected for 3 weeks inside two operating rooms for 24 h at 38 L/min in quartz filters. RNA was extracted from the filters and analyzed using RT-qPCR targeting SARS-CoV-2 genes E, N1 and N2 regions. SARS-CoV-2 RNA was detected in 11.3% of aerosol samples collected in operating rooms, despite with low concentrations (not detected at 13.5 cg/m3 and 10.5 cg/m3 in the scheduled and emergency operating rooms, respectively). Potential sources of airborne SARS-CoV-2 could be aerosolization of the virus during aerosol-generating procedures and in open surgery from patients that might have been recently infected with the virus, despite presenting a negative COVID-19 test. Another source could be related to health care workers unknowingly infected with the virus and exhaling SARS-CoV-2 virions into the air. These results highlight the importance of reinforcing preventive measures against COVID-19 in operating rooms, such as the correct use of protective equipment, screening programs for health care workers, and information campaigns. IMPORTANCE Operating rooms are critical environments in which asepsis must be ensured. The COVID-19 pandemic entailed the implementation of additional preventative measures in health care settings, including operating theaters. Although one of the measures is to operate only COVID-19 free patients, this measure cannot be always implemented, especially in emergency interventions. Therefore, a surveillance campaign was conducted during 3 weeks in two operating rooms to assess the level of SARS-CoV-2 genetic material detected in operating theaters with the aim to assess the risk of COVID-19 transmission during operating procedures. SARS-CoV-2 genetic material was detected in 11% of aerosol samples collected in operating rooms, despite with low concentrations. Plausible SARS-CoV-2 sources have been discussed, including patients and health care personnel infected with the virus. These results highlight the importance of reinforcing preventive measures against COVID-19 in operating rooms, such as the correct use of protective equipment, screening programs for health care workers and information campaigns.

Transformation of low-volatility gaseous precursors to new particles affects aerosol number concentration, cloud formation and hence the climate. The clustering of acid and base molecules is a major mechanism driving fast nucleation and initial growth of new particles in the atmosphere. However, the acid-base cluster composition, measured using state-of-the-art mass spectrometers, cannot explain the measured high formation rate of new particles. Here we present strong evidence for the existence of base molecules such as amines in the smallest atmospheric sulfuric acid clusters prior to their detection by mass spectrometers. We demonstrate that forming (H2SO4)1(amine)1 is the rate-limiting step in atmospheric H2SO4-amine nucleation and the uptake of (H2SO4)1(amine)1 is a major pathway for the initial growth of H2SO4 clusters. The proposed mechanism is very consistent with measured new particle formation in urban Beijing, in which dimethylamine is the key base for H2SO4 nucleation while other bases such as ammonia may contribute to the growth of larger clusters. Our findings further underline the fact that strong amines, even at low concentrations and when undetected in the smallest clusters, can be crucial to particle formation in the planetary boundary layer.

The sulfate anion radical (SO4•-) is known to be formed in the autoxidation chain of sulfur dioxide and from minor reactions when sulfate or bisulfate ions are activated by OH radicals, NO3 radicals, or iron. Here, we report a source of SO4•-, from the irradiation of the liquid water of sulfate-containing organic aerosol particles under natural sunlight and laboratory UV radiation. Irradiation of aqueous sulfate mixed with a variety of atmospherically relevant organic compounds degrades the organics well within the typical lifetime of aerosols in the atmosphere. Products of the SO4•- + organic reaction include surface-active organosulfates and small organic acids, alongside other products. Scavenging and deoxygenated experiments indicate that SO4•- radicals, instead of OH, drive the reaction. Ion substitution experiments confirm that sulfate ions are necessary for organic reactivity, while the cation identity is of low importance. The reaction proceeds at pH 1-6, implicating both bisulfate and sulfate in the formation of photoinduced SO4•-. Certain aromatic species may further accelerate the reaction through synergy. This reaction may impact our understanding of atmospheric sulfur reactions, aerosol properties, and organic aerosol lifetimes when inserted into aqueous chemistry model mechanisms.

Abstract Background Electronic cigarettes (EC) have gained popularity, especially among young people, with the introduction of fourth-generation devices based on e-liquids containing nicotine salts that promise a smoother vaping experience than freebase nicotine. However, the toxicological effects of nicotine salts are still largely unknown, and the chemical diversity of e-liquids limits the comparison between different studies to determine the contribution of each compound to the cytotoxicity of EC aerosols. Therefore, the aim of this study was to evaluate the toxicological profile of controlled composition e-liquid aerosols to accurately determine the effects of each ingredient based on exposure at the air-liquid interface. Methods Human lung epithelial cells (A549) were exposed to undiluted aerosols of controlled composition e-liquids containing various ratios of propylene glycol (PG)/vegetable glycerin (VG) solvents, freebase nicotine, organic acids, nicotine salts, and flavoured commercial e-liquids. Exposure of 20 puffs was performed at the air-liquid interface following a standard vaping regimen. Toxicological outcomes, including cytotoxicity, inflammation, and oxidative stress, were assessed 24 h after exposure. Results PG/VG aerosols elicited a strong cytotoxic response characterised by a 50% decrease in cell viability and a 200% increase in lactate dehydrogenase (LDH) production, but had no effects on inflammation and oxidative stress. These effects occurred only at a ratio of 70/30 PG/VG, suggesting that PG is the major contributor to aerosol cytotoxicity. Both freebase nicotine and organic acids had no greater effect on cell viability and LDH release than at a 70/30 PG/VG ratio, but significantly increased inflammation and oxidative stress. Interestingly, the protonated form of nicotine in salt showed a stronger proinflammatory effect than the freebase nicotine form, while benzoic acid-based nicotine salts also induced significant oxidative stress. Flavoured commercial e-liquids was found to be cytotoxic at a threshold dose of ≈ 330 µg/cm². Conclusion Our results showed that aerosols of e-liquids consisting only of PG/VG solvents can cause severe cytotoxicity depending on the concentration of PG, while nicotine salts elicit a stronger pro-inflammatory response than freebase nicotine. Overall, aerosols from fourth-generation devices can cause different toxicological effects, the nature of which depends on the chemical composition of the e-liquid.

The results of lidar sensing of aerosol pollution in St. Petersburg (Russia) were compared with ones located in Minsk (Belarus) and Kuopio (Finland) to assess the impact of large cities on atmospheric pollution by aerosol particles. For comparison, aerosol optical depth (AOD) data obtained at the three stations from 2014 to 2021 were used. Lidar sounding of atmospheric aerosols was carried out using aerosol Nd:YAG lasers operating at three wavelengths: 355, 532 and 1064 nm. Due to differences in the lidar station equipment characteristics and, consequently, in the lower limit for determining aerosols, the aerosol optical depth was compared in the range of heights from 800 to 1600 m at 355 and 532 nm. Since the compared stations do not have data for all years, the period from 2014 to 2016 was analyzed separately. The average annual AOD 355 in Minsk in the period 2014-2016 is almost the same as the average annual AOD in St. Petersburg. When comparing data in St. Petersburg and Minsk for the period 2014-2020, AOD 355 in St. Petersburg exceeds AOD 355 in Minsk by 1.46 times. AOD 532 nm in Minsk is larger than in St. Petersburg, regardless of the chosen comparison period. The average annual AOT 355 in Kuopio is lower than in Minsk and St. Petersburg by 2.1 times, while at a wavelength of 532 nm they are 3.6 times lower than in Minsk and 2.6 times in St. Petersburg. The calculated Angstrom exponent coefficient shows that the coarse mode in Minsk is higher than in St. Petersburg. The atmosphere over Kuopio has a lower content of aerosol particles. Since 2017, there was a steady excess of aerosol content over St. Petersburg compared to Minsk. Additionally, a comparison of the lidar data with the total AOD of AERONET stations located in Kuopio, Minsk and Peterhof (25 km from the lidar station in St. Petersburg) was carried out. The AOD obtained by lidar and AERONET method is in good agreement.

Heated tobacco products (HTPs) are a recent category of tobacco products, with their relative safety compared to cigarette smoking and potential to help smokers to quit being two reasons why regulators may consider their market approval. Designed to heat tobacco rather than to burn in order to produce aerosol, different heating techniques are applied to commercial HTPs, which may result in differing aerosol formation. Therefore, each product requires separate assessment. This work focuses on a closed-end HTP (coded as HTP-A), which is electrically heated and designed to allow puffing air flow to bypass its tobacco section, resulting in reduced oxygen concentration within the tobacco section during heating and aerosol forming. To provide a preliminary aerosol chemistry and in vitro toxicological screening, this study assessed HTP-A against a commercial electrically heated HTP (IQOSTM, coded as HTP-B) and a 3R4F reference cigarette. Under Health Canada Intense (HCI) smoking regime, the levels of 9 regulatory priority toxicants in the aerosol of HTP-A were either reduced or comparable to those in HTP-B on a per-stick basis. Additionally, both HTPs showed significant reduction (greater than 90%) in comparison to those measured in mainstream smoke of 3R4F cigarette for these toxicants. Using a set of standard in vitro toxicological assays (Ames, Micronucleus and Neutral Red Uptake), the two HTPs showed no observable responses while significant toxicity responses were recorded for 3R4F’s total particulate matter. Based on these preliminary results, the novel closed-end HTP-A design may provide similar toxicological profiles to the comparator HTP-B. Further toxicological and clinical assessments are warranted to evaluate HTP-A’s potential for exposure or disease risk reduction. [Contrib. Tob. Nicotine Res. 32 (2023) 146–156]

In the recent years, great progress has been made in developing terrestrial and satellite-based networks for the measurement of atmospheric parameters, which serve as inputs in clear sky parametric models. However, some parameters may still be missing from the model input due to small temporal sampling or lack of in situ data. This paper presents a case study on the accuracy of the clear-sky solar irradiance estimation by a parametric model, when the availability of inputs is limited. The study was conducted with high-quality radiometric and atmospheric data recorded by the INOE-Magurele station, Romania. Seven different scenarios were studied. In each scenario the clear-sky solar irradiance model was run assuming that certain parameters are missing from the input. The results quantitatively confirm the dominant role of aerosols in establishing the accuracy of solar irradiance estimation under clear sky conditions. The unavailability of the measured Ångström turbidity coefficient may lead to a twofold/threefold increase in the uncertainty of direct-normal/diffuse solar irradiance estimation.

To monitor health risks associated with vaping, we introduce a multi-spectral optical sensor powered by machine learning for real-time characterization of electronic cigarette aerosols. The sensor can accurately measure the mass of particulate matter (PM) in specific particle size channels, providing essential information for estimating lung deposition of vaping aerosols. For the sensor’s input, wavelength-specific optical attenuation signals are acquired for three separate wavelengths in the ultraviolet, red, and near-infrared range, and the inhalation pressure is collected from a pressure sensor. The sensor’s outputs are PM mass in three size bins, specified as 100–300 nm, 300–600 nm, and 600–1000 nm. Reference measurements of electronic cigarette aerosols, obtained using a custom vaping machine and a scanning mobility particle sizer, provided the ground truth for size-binned PM mass. A lightweight two-layer feedforward neural network was trained using datasets acquired from a wide range of puffing conditions. The performance of the neural network was tested using unseen data collected using new combinations of puffing conditions. The model-predicted values matched closely with the ground truth, and the accuracy reached 81–87% for PM mass in three size bins. Given the sensor’s straightforward optical configuration and the direct collection of signals from undiluted vaping aerosols, the achieved accuracy is notably significant and sufficiently reliable for point-of-interest sensing of vaping aerosols. To the best of our knowledge, this work represents the first instance where machine learning has been applied to directly characterize high-concentration undiluted electronic cigarette aerosols. Our sensor holds great promise in tracking electronic cigarette users’ puff topography with quantification of size-binned PM mass, to support long-term personalized health and wellness.

Serious concerns exist that the increasing frequency of fires may delay the recovery of ozone given increasing temperatures due to climate change. Australian bushfires from September 2019 to February 2020 were catastrophic. A random forest spatial-temporal (RF sp) analysis using satellite data to detect an association between Australian bushfires and stratosphere ozone on the local depletion of ozone in the vicinity of fires in three regions of Australia (Pacific Ocean, Victoria, NSW) has shown a significant reduction in ozone attributable to aerosols from fires. By intervention analysis, increases in aerosols in all three regions were shown to have a significant and ongoing impact 1–5 days later on reducing ozone (p < 0.0001). Intervention analysis also gave similar periods of aerosol exceedance to those found by Hidden Markov models (HMMs). HMMs established a significant and quantifiable decline in ozone due to bushfire-induced aerosols, with significant lags of 10–25 days between times of aerosol exceedance and subsequent ozone level decline in all three regions.

Background: The use of probiotic bacteria to improve lung health has been gaining interest. Although the oral delivery of probiotics and their effects are well documented, there is currently limited knowledge on the respiratory delivery of probiotics. Objectives: This study aimed to investigate whether nebulisation is suitable for delivering Lacticaseibacillus rhamnosus GG (LGG) into the lungs for the potential treatment of bacterial pulmonary infections. Methods: It compared the dose output and aerosol performance of a vibrating-mesh nebuliser (VMN) and a jet nebuliser (JN) in nebulising LGG suspended in de Man Rogosa Sharpe (MRS) broth, phosphate-buffered saline (PBS), or normal saline (0.9% w/v sodium chloride in water). Results: The VMN consistently produced a higher output than the JN for all liquid media, indicating that VMN was more efficient. The fine-particle fractions of both nebulisers were comparable for a given medium. The highest fine-particle fraction was achieved with LGG suspended in MRS broth for both nebulisers (20.5 ± 2.8% for VMN; 18.7 ± 3.4% for JN). This suggests that the aerosol performance of nebulised probiotics may depend on the medium in which the probiotic bacteria were suspended. Conclusions: Therefore, this study demonstrated that the nebulisation efficiency of LGG depended on the nebuliser type and liquid medium of the probiotic suspension.

Palytoxins are a group of highly potent and structurally complex marine toxins that rank among some of the most toxic substances known to science. Palytoxins are naturally synthesized by a variety of marine organisms, including Palythoa zoanthids, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria, and are widely distributed in tropical and temperate regions where they can bioaccumulate in marine life. The evolution of research on palytoxins has been an intricate exchange between interdisciplinary fields, drawing insights from chemistry, biology, medicine, and environmental science in efforts to better understand and mitigate the health risks associated with this family of toxins. In this review, we begin with a brief history covering the discovery of this group of toxins and the events that led to its isolation. We then focus on the chemical structure of these compounds and their proposed mechanism of action. Finally, we review in vitro, ex vivo, and in vivo studies related to their toxicity, with the aim to provide a broad overview of the current knowledge on palytoxin toxinology.

A quasi-consensus has steadily formed in the scientific literature on the fact that the prevention measures implemented by most countries to curb the 2020 COVID-19 pandemic have led to significant reductions in pollution levels around the world, especially in urban environments. Fewer studies have looked at how these reductions at the ground level translate into variations in the whole atmosphere. In this study, we examine the columnar values of aerosols at 51 mainland European stations of the Aerosol Robotic Network (AERONET). We show that when considered in the context of the long-term trend over the last decade, the columnar aerosol levels for 2020, at the regional level, do not appear exceptional. Both the yearly means and the number of episodes with extreme values for this period are within one standard deviation of the long-term trends. We conclude that the spatially and temporally localized reductions do not add up to statistically significant reductions at the global levels of aerosols. Furthermore, considering that pandemic lockdowns can be thought of as a simulation of a climate change mitigation scenario, we conclude that such lifestyle-based changes present a very low potential as a global climate change mitigation strategy.

This study presents an improved wet scavenging process for particles in air quality modeling, focusing on the Korean Peninsula. New equations were incorporated into the air quality chemical transport model (CTM) to enhance the simulation of particulate matter (PM) concentrations. The modified air quality CTM module, utilizing size-dependent scavenging formulas, was applied to simulate air quality for April 2018, a month characterized by significant precipitation. Results showed that the modified model produced more accurate predictions of PM10 and PM2.5 concentrations compared to the original air quality CTM model. The maximum monthly average differences were 5.46 µg/m3 for PM10 and 2.87 µg/m3 for PM2.5, with pronounced improvements in high-concentration regions. Time-series analyses for Seoul and Busan demonstrated better agreement between modeled and observed values. Spatial distribution comparisons revealed enhanced accuracy, particularly in metropolitan areas. This study highlights the importance of incorporating region-specific, size-dependent wet scavenging processes in air quality models. The improved model shows promise for more accurate air quality predictions, potentially benefiting environmental management and policy-making in the region. Future research should focus on integrating more empirical data to further refine the wet scavenging process in air quality modeling.