Aerosol Particle Size Research Articles

Numerical study of the influence of dispersed phase parameters on the gas flow generation formed by gravitational deposition of aerosol

In this paper, non-stationary processes in an inhomogeneous medium are investigated. The dynamics of inhomogeneous media is largely determined by the effects caused by interfacial interaction, the intensity of which depends on the properties of a dispersed phase. The goal is to study the effect of volumetric content, density of the dispersed phase material and the size of aerosol particles on the motion of the carrier medium. The object of study are aerosols - gas-droplet and dusty environments. As a rule, the movement of the mixture is initiated by the movement of the carrier phase. This study addresses the flow of gas arising from the deposition of particles of a gas suspension. The effect of the dispersed phase of a two-phase mixture on gas motion during gravitational aerosol deposition is investigated numerically. The mathematical model consists of equations describing the dynamics of a carrier medium and those describing the dynamics of a dispersed component. It has been assumed that the dispersed component of the mixture is deposited in the Stokes regime. The system of equations of the dynamics of a carrier medium involves continuity, momentum, and energy equations. The carrier medium is described as a viscous, compressible and heat-conducting gas. Interfacial interaction is determined by the Stokes force. The mathematical model takes into account interphase heat transfer. The equations of the mathematical model are integrated by the explicit finite-difference McCormack method with a second-order error. A nonlinear correction of the grid function is used to obtain a monotonous numerical solution, which makes it possible to overcome the numerical oscillation in the resulting solution. The equations are supplemented by initial and boundary conditions. Numerical calculations of the gravitational deposition of a dispersed phase have shown the formation of a gas flow, and simulations of the gravitational deposition of an aerosol have revealed an uneven distribution of gas pressure caused by the flow of the carrier medium. Numerical modeling demonstrates that, depending on the parameters of the dispersed component of the gas suspension, different intensities of the gas flow can be observed.

Vertical distribution of aerosol mass concentration over Pearl River Delta observed by Lidar during autumn and winter

This study aims to analyze the vertical distribution of aerosol particles during autumn and winter by deriving the number density of aerosol particles from Mie Lidar return signals. Haze has always existed in regions with low humidity and stable weather. In such regions,particle vertical distribution characters are needed for transport mechanisms. As a widely used instrument, Mie Lidar surfer from the uncertainties caused by the Lidar ratio and boundary value assumption. However, Mie Lidar is the most powerful tool to observe the atmospheric vertical distribution because it performs well in day and night under all weather conditions in comparison with passive sensors.Moreover, Mie Lidar is easier to carry compared with Raman Lidar.Lidar radiation principles were studied to understand the Lidar equation and its solution. Several parameters were carefully chosen for the numerical solutions. Instead of using boundary value for approximation, the Lidar parameter k was directly calculated on the basis of Lidar-validated parameters to avoid uncertainties. Thus, aerosol particles backscatter and extinction coefficient were retrieved by solving the Lidar equation and integrated for Aerosol Optical Depth(AOD) results. A Cimel CE318 sun photometer and an ASD Field Spec3 were used to measure AOD as validation data. Lastly, the number density of aerosol particles was derived on the basis of Mie theory with the estimation of aerosol particle distribution, size, and refractive index of particles.According to the number density vertical profile, nearly no difference was observed between the number density vertical profile of aerosol particles during daytime and nighttime in one day at a low altitude. This result indicated that the sunlight effect is ignorable for aerosol particle distribution near ground. The retrieved AODs with the CE318 and ASD observations showed a root mean square error of approximately 0.0541 and 0.0100, demonstrating that the retrieved result is reliable. The comparison with traditional method showed that the proposed algorithm in this study improved the accuracy of the traditional Lidar equation solution. The near-real distribution results showed aerosol particle distribution characteristics near the ground. The number density of aerosol particles in Guangzhou was mainly distributed in low-altitude regions, and its relationship with height was approximately a negative exponential distribution. The retrieved results of the aerosol particle number density were similar to those from the previous years, indicating that the air pollution in Guangzhou has not worsened. However, potential environmental threats and air pollution problems still need to be governed.Several uncertainties, such as changes in air temperature and pressure, validation of Lidar instrument k, and overlap factor, that could cause deviation were identified. The overlap factor and molecular backscatter coefficient were carefully calculated using the theoretical method. Frequent updates on Lidar parameters will be requested from the Lidar company in the future. The theoretical and experimental methods were combined for the calculation of the overlap factor and molecular backscatter coefficient. Raman Lidar was used to measure the actual Lidar ratios and characteristics of molecular scatter.The aerosol particle number density-retrieved algorithm was based on Lidar radiation principles and revealed the particles’ spatial distribution characters. The vertical distribution characters remained unchanged for several days under stable weather in the autumn and winter seasons, and its relationship with height was approximately a negative exponential distribution;hence, air conditions can have huge effect on human health. Air pollution problem still needs to be governed.

Changes in aerosol size distributions over the Indian Ocean during different meteorological conditions

Aerosol emissions in South Asia are large. The emitted aerosols can travel significant distances and, during the Asian southwest monsoon especially, are prone to modification through cloud processing and wet scavenging while being transported. The scale of emissions and transport means that the global climate impact of these aerosols are sensitive to modification en route, but the process-level understanding is still largely lacking. In this study, we analyse long-term aerosol data measured at an observatory established in Hanimaadhoo, Republic of Maldives, to investigate the long-term properties of aerosols over the Indian Ocean as well as to understand the effect of precipitation on the aerosol particle size distribution during long-range transport. The observatory location is ideal because it is a receptor site with little local influence, and, depending on the season, receives either polluted air masses coming from the Indian subcontinent or clean marine air masses from the Indian Ocean. We analysed the sub-micron particle number size distribution measured during the years 2004–2008, and 2014–2017, and this is the first inter-seasonal long-term study of the sub-micron aerosol features in the region. The aerosol origin and its relative exposure to wet scavenging during long-range transport were analysed using back-trajectory analysis from HYSPLIT. By comparing aerosol measurements to precipitation along its transport, this study shows that there is a substantial change in particle number size distributions and concentrations depending on the amount of rainfall during transport. During the southwest monsoon season, the aerosol size distribution was notably bi-modal and total particle concentrations clearly reduced in comparison with the prevailing aerosol size distribution during the northeast monsoon season. Precipitation during transport usually corresponded with a greater reduction in accumulation mode concentrations than for smaller sizes, and the shape of the median size distribution showed a clear dependence on the trajectory origin and route taken.

Physical and chemical properties of aerosol particles and cloud residuals on Mt. Åreskutan in Central Sweden during summer 2014

The size distribution, volatility and hygroscopicity of ambient aerosols and cloud residuals were measured with a differential mobility particle sizer (DMPS) and a volatility–hygroscopicity tandem differential mobility analyser (VHTDMA) coupled to a counterflow virtual impactor (CVI) inlet during the Cloud and Aerosol Experiment at Åre (CAEsAR) campaign at Mt. Åreskutan during summer 2014. The chemical composition of particulate matter (PM) and cloud water were analysed offline using thermo-optical OC/EC analysis and ion chromatography. The importance of aerosol particle size for cloud droplet activation and subsequent particle scavenging was clearly visible in the measured size distributions. Cloud residuals were shifted towards larger sizes compared to ambient aerosol, and the cloud events were followed by a size distribution dominated by smaller particles. Organics dominated both PM (62% organic mass fraction) and cloud water (63% organic mass fraction) composition. The volatility and hygroscopicity of the ambient aerosols were representative of homogeneous aged aerosol with contributions from biogenic secondary organics, with median volume fraction remaining (VFR) of 0.04–0.05, and median hygroscopicity parameter κ of 0.16–0.24 for 100–300 nm particles. The corresponding VFR and κ for the cloud residuals were 0.03–0.04 and 0.18–0.20. The chemical composition, hygroscopicity and volatility measurements thus showed no major differences between the ambient aerosol particles and cloud residuals. The VFR and κ values predicted based on the chemical composition measurements agreed well with the VHTDMA measurements, indicating the bulk chemical composition to be a reasonable approximation throughout the size distribution. There were indications, however, of some more subtle changes in time scales not achievable by the offline chemical analysis applied here. Further, online observations of aerosol and cloud residual chemical composition are therefore warranted.

Effect of storage at high temperature on chemical (composition) and techno-functional characteristics of E471 food emulsifiers applied to aerosol whipping cream

Various foods are processed with addition of mono- and diacylglycerol (MAG and DAG) emulsifiers to adjust techno-functional properties. Exposure to and application of high temperatures during production, processing and transport of these emulsifiers can induce compositional changes and thereby affect techno-functional properties. Emulsifiers were stored above their respective melting point and their chemical composition was determined by high-performance thin-layer chromatography–fluorescence detection. Storage for 8 weeks decreased the MAG content of a saturated MAG by about 36% by transesterification into 1,3-DAG, while a rearrangement of 1,2- into 1,3-DAG was observed for a saturated MAG/DAG emulsifier. Emulsifiers were applied to aerosol whipping cream, and viscosity, particle size, overrun, foam firmness and drainage were determined. The increasing 1,3-DAG content of the saturated MAG emulsifier was found to increase the drainage of aerosol whipping cream from 15% to 50%.

Physical and chemical properties of non-exhaust particles generated from wear between pavements and tyres

A road simulator was used to generate wear particles from the interaction between two tyre brands and a composite pavement. Particle size distributions were monitored using a scanning mobility particle sizer and an aerosol particle sizer. Continuous measurements of particle mass concentrations were also made. Collection of inhalable particles (PM10) was conducted using a high-volume sampler equipped with quartz filters, which were then analysed for organic and elemental carbon, organic constituents and elemental composition. Tyre fragments chopped into tiny chips were also subjected to detailed organic and elemental speciation. The number concentration was dominated by particles <0.5 μm, whereas most of the mass was found in particles >0.5 μm. The emission factor from wear between pavements and tyres was of the order of 2 mg km−1 veh−1. Organic carbon represented about 10% of the PM10 mass, encompassing multiple aliphatic compounds (n-alkanes, alkenes, hopanes, and steranes), PAHs, thiazols, n-alkanols, polyols, some fragrant compounds, sugars, triterpenoids, sterols, phenolic constituents, phthalate plasticisers and several types of acids, among others. The relationship between airborne particulate organic constituents and organic matter in tyre debris is discussed. The detection of compounds that have been extensively used as biomass burning tracers (e.g. retene, dehydroabietic acid and levoglucosan) in both the shredded tiny tyre chips and the wear particles from the interaction between tyres and pavement puts into question their uniqueness as markers of wood combustion. Trace and major elements accounted for about 5% of the mass of the tyre fragments but represented 15–18% of the PM10 from wear, denoting the contribution of mineral elements from the pavement. Sulphur and zinc were abundant constituents in all samples.

Analysis and Evaluation of Contamination Status of Polycyclic Aromatic Hydrocarbons (PAHs) in Settled House and Road Dust Samples from Hanoi

Analysis and Evaluation of Contamination Status of Polycyclic Aromatic Hydrocarbons (PAHs) in Settled House and Road Dust Samples from Hanoi

Green electrospun nanofiber membranes filter prepared from novel biomass thermoplastic copolyester: Morphologies and filtration properties

Abstract High-performance and eco-friendly nonwoven-nanofiber filters comprising renewably sourced bio-based polyesters were fabricated by electrospinning (ES). Typical commercial nonwoven filters are thick, with uneven fiber distributions and low recovery. Bio-based polymers made of raw plant materials have soft textures. Over 75% of the polyester used herein was sourced renewable. We observed variations in its morphology under different operating conditions in scanning electron microscope images by tuning the operating parameters of ES and using different DMF/CHCl3 solvent ratios. We produced various types of ES nanofibers with uniform fiber diameters ranging from 400 to 2000 nm, which increased filter efficiency and helped overcome existing shortcomings in filter applications. A scanning mobility particle sizer and NaCl aerosol particles of sizes 30–300 nm were used to test the prepared nanofiber filters. Owing to their high specific surface areas/volume ratios and small-fiber diameters, the nanofiber filters with fiber diameters smaller than 500 nm forcefully resisted the majority of suspended particles. The averaged penetration ability of ES fiber was decreased from 30% to 4%, with increasing heating temperature and annealing time. Thicker ES fibers with beaded morphologies exhibited average penetration

Key drivers of cloud response to surface-active organics

Aerosol-cloud interactions constitute the largest source of uncertainty in global radiative forcing estimates, hampering our understanding of climate evolution. Recent empirical evidence suggests surface tension depression by organic aerosol to significantly influence the formation of cloud droplets, and hence cloud optical properties. In climate models, however, surface tension of water is generally assumed when predicting cloud droplet concentrations. Here we show that the sensitivity of cloud microphysics, optical properties and shortwave radiative effects to the surface phase are dictated by an interplay between the aerosol particle size distribution, composition, water availability and atmospheric dynamics. We demonstrate that accounting for the surface phase becomes essential in clean environments in which ultrafine particle sources are present. Through detailed sensitivity analysis, quantitative constraints on the key drivers – aerosol particle number concentrations, organic fraction and fixed updraft velocity – are derived for instances of significant cloud microphysical susceptibilities to the surface phase.

Urban Aerosol Particle Size Characterization in Eastern Mediterranean Conditions

Characterization of urban particle number size distribution (PNSD) has been rarely reported/performed in the Middle East. Therefore, we aimed at characterizing the PNSD (0.01–10 µm) in Amman as an example for an urban Middle Eastern environment. The daily mean submicron particle number concentration (PNSub) was 6.5 × 103–7.7 × 104 cm−3 and the monthly mean coarse mode particle number concentration (PNCoarse) was 0.9–3.8 cm−3 and both had distinguished seasonal variation. The PNSub also had a clear diurnal and weekly cycle with higher concentrations on workdays (Sunday–Thursday; over 3.3 × 104 cm−3) than on weekends (below 2.7 × 104 cm−3). The PNSub constitute of 93% ultrafine fraction (diameter &lt; 100 nm). The mean particle number size distributions was characterized with four well-separated submicron modes (Dpg,I, Ni): nucleation (22 nm, 9.4 103 cm−3), Aitken (62 nm, 3.9 103 cm−3), accumulation (225 nm, 158 cm−3), and coarse (2.23 µm, 1.2 cm−3) in addition to a mode with small geometric mean diameter (GMD) that represented the early stage of new particle formation (NPF) events. The wind speed and temperature had major impacts on the concentrations. The PNCoarse had a U-shape with respect to wind speed and PNSub decreased with wind speed. The effect of temperature and relative humidity was complex and require further investigations.

Particle-Size Variability of Aerosol Iron and Impact on Iron Solubility and Dry Deposition Fluxes to the Arctic Ocean

This study provides unique insights into the properties of iron (Fe) in the marine atmosphere over the late summertime Arctic Ocean. Atmospheric deposition of aerosols can deliver Fe, a limiting micronutrient, to the remote ocean. Aerosol particle size influences aerosol Fe fractional solubility and air-to-sea deposition rate. Size-segregated aerosols were collected during the 2015 US GEOTRACES cruise in the Arctic Ocean. Results show that aerosol Fe had a single-mode size distribution, peaking at 4.4 µm in diameter, suggesting regional dust sources of Fe around the Arctic Ocean. Estimated dry deposition rates of aerosol Fe decreased from 6.1 µmol m−2 yr−1 in the areas of ~56°N–80°N to 0.73 µmol m−2 yr−1 in the areas north of 80°N. Aerosol Fe solubility was higher in fine particles (<1 µm) which were observed mainly in the region north of 80°N and coincided with relatively high concentrations of certain organic aerosols, suggesting interactions between aerosol Fe and organic ligands in the high-latitude Arctic atmosphere. The average molar ratio of Fe to titanium (Ti) was 2.4, substantially lower than the typical crustal ratio of 10. We speculate that dust sources around the Arctic Ocean may have been altered because of climate warming.

Electrospun meta-aramid/polysulfone-amide nanocomposite membranes for the filtration of industrial PM2.5 particles

Filtering of industrial PM2.5 is a major challenge for global environmental and animal protection. Filtering of materials with excellent thermal stability and other comprehensive performances is required for the removal of fine particles in high-temperature operating industries such as steel, cement, metallurgy, incineration, etc. In this study, a meta-aramid/polysulfone-amide (PMIA/PSA) composite nanofibrous filtration membrane is prepared via solution electrospinning for the development of high-temperature-resistant filtering products. To maximize the merits of each component, PMIA/PSA composite nanofibrous membranes with different mass blending ratios are prepared to determine the optimal balance. It is found that the PMIA/PSA composite nanofibrous membranes show excellent thermal stability and thermal shrinkage performance. They also maintain superb mechanical retention ratios after 200 h treatment at 200 °C. In addition, they exhibit excellent removal efficiency of polystyrene aerosol (PSL) particles of various sizes. It is found that the removal efficiency of PMIA/PSA (3/7) is 96.7% for 0.1 μm, 98.3% for 0.2 μm and 99.6% for 0.3 μm particles and it possesses optimal filtration resistance (79 Pa), while other composite membranes can reach a removal efficiency of over 99.7%. Our experimental results illustrate that the filtration efficiency for PM2.5 of PMIA/PSA (7/3), (5/5) composite nanofibrous membranes is still kept as high as 99.9% even after being treated at 200 °C for 120 h. It indicates that the prepared composite nanofibrous membranes have potential for applications where high-efficiency filtration is desired, such as bag dust filters for use under high temperatures.

Large Summer Contribution of Organic Biogenic Aerosols to Arctic Cloud Condensation Nuclei

AbstractA k‐means cluster analysis of a 5‐year aerosol particle size distribution data set from northeast Greenland is combined with measurements of coincident shorter field studies of aerosol equivalent black carbon (eBC) content, hygroscopic growth factor (HGF), and cloud condensation nuclei (CCN) concentrations. This led to five clusters strongly controlled by natural emissions (eBC 8–15 ng/m3) and three anthropogenic clusters with larger particle concentrations in the accumulation mode (eBC 29–77 ng/m3). The HGF and CCN properties of the eight aerosol clusters differ drastically. Anthropogenic clusters feature high growth factors (1.62–1.81) and low CCN κ values (0.10–0.46), while natural clusters show lower HGF (1.38–1.70) but remarkably higher κ values (0.35–0.51). Extrapolating the CCN properties on the basis of the cluster analysis to annual timescales suggests that biogenic organic aerosol may drive Arctic aerosol production during summer.

The Study of Particle Size Distribution of Electroerosion Chrome-Containing Powder, Used for Wear Resistant Surfacing

Perpose of research. To study the particle size distribution of electroerosive chrome-containing powder, suitable for surfacing. Methods. To carry out the planned studies, chrome-containing steel wastes were selected. The carbon-containing working fluid was chosen as the working fluid, namely, lighting kerosene. To obtain chrome-containing powder materials by electroerosive dispersion the device for EED of conductive materials was used. The dispersible material was poured into a desiccator, filled with a working fluid, namely, lighting kerosene. The authors studied the particle size distribution of the obtained powders by the method of dispersion in a liquid with ultrasound. Research technique (FR 1.27.2009.06762 “Methodology for measuring particle size in suspensions, emulsions and aerosols in the nanometer and colloidal ranges using the effect of dynamic light scattering”) has been used. Results. It is experimentally established that the particle shape of the obtained powder material is due to the form in which the material is ejected from the hole during the EED process. It is also seen that particles having a regular spherical or elliptical shape prevail in the powder material. They are obtained by crystallization of the molten material (liquid phase). The particles formed during crystallization of the boiling material (vapor phase) have an irregular shape, an order of magnitude smaller than the particles formed by their liquid phase, and usually agglomerate with each other on the surface of other particles. In the EED process, such particles are most susceptible to chemical and phase changes. Conclusion. Studies of the particle size distribution of chrome-containing powder material obtained by electroerosive dispersion of waste in lighting kerosene under the following electrical parameters of the operation of the EED unit: capacity of discharge capacitors 45 μF, voltage at the electrodes 100 ... 110 V, pulse repetition rate of the generator 55 ... 65 Hz determine the average particle size of the powder material and the specific surface area. The results will allow us to determine the rational area of their practical application.

Satellite-based identification of aerosol particle species using a 2D-space aerosol classification model

The classification of aerosol types using remote sensing tools is crucial for improving our knowledge on the impacts of aerosol species on global and regional climate. Ground-based classification methods have proven useful though they are limited by discontinuous spatial observations of aerosol optical properties. As such, there is a need to develop methods in aerosol species identification using satellite data. In this study, a 2D-space model suitable for MODIS AOD bands is developed to distinguish aerosol particle species based on aerosol optical depth (AOD) and aerosol relative optical depth (AROD). The model can be used to classify five aerosol types, including biomass burning (BB: AOD470 ≥ 0.45, AROD660/470 < 0.58), urban industry (UI: AOD470 ≥ 0.45, 0.68 > AROD660/470 ≥ 0.58), sub-continental (SB: AOD470 ≥ 0.45, 0.91 > AROD660/470 ≥ 0.68), desert dust (DD: AROD660/470 ≥ 0.91) and continental (CO: AOD470 < 0.45, AROD660/470 < 0.91). AROD values corresponding to different types of aerosols are calculated through Mie scattering theory using the aerosol particle size distribution parameters and spectral complex refractive index. The accuracy and applicability of the model are verified in three steps: 1) we compare aerosol discrimination results of model with ground-based data and the local atmospheric conditions over different regions, 2) we compare aerosol identification results from Moderate Resolution Imaging Spectroradiometer (MODIS) AOD retrieval and ground-based data, and 3) we test our model to validate its use in individual cases studies and regional observations. Our results demonstrate that aerosol species classification for each study region is consistent with the characteristics of their atmospheric conditions, and the classification results using MODIS AOD retrieval are similar to the ground-based observation results. The differences in MODIS versus AERONET AOD, caused by MODIS observation errors, is the major contributor to the differences between ground-based and satellite-based recognition results. Our three-steps validation results indicate that the 2D-space model developed in this paper can accurately identify different types of aerosols and has strong applicability. This provides a basis for the use of satellite data for continuous spatial identification of aerosol type, which greatly promotes research in related fields.

Aerosol Particle Size and Breathing Pattern During Inhaled Furosemide

Aerosol Particle Size and Breathing Pattern During Inhaled Furosemide

Improved algorithm of aerosol particle size distribution based on remote sensing data.

The optical parameters (extinction or backscatter coefficients) of multi-wavelength beams can be used for the retrieval of the aerosol particle size distribution (APSD). An improved algorithm for APSD and aerosol microphysical parameters (AMPs) is studied and discussed by using only multi-wavelength extinction coefficients data. The regularized algorithm and prior value are combined for the retrieval of APSD and AMPs. The regularization algorithm, based on minimum discrepancy principle and averaging procedure, is used for the retrieval of fine-mode APSD and an averaging procedure that can achieve stable outputs is proposed. The 1% averaging result near the minimum of the discrepancy is selected and verified. Based on the inversion results of fine mode from the regularization algorithm, the lognormal distribution with a prior value (model radius) is applied to reconstruct the coarse mode of APSDs through fitting the data. The comprehensive application of the regularization algorithm and averaging process improves the stability of the inversion in the fine mode, and the use of the prior value broadens the inversion radius range of APSD. The complex refractive index need not be assumed for this method. The inversion error for different types of aerosols is analyzed and studied. The reliability of the algorithm is tested and verified by many typical APSDs and the measured APSDs by particle size spectrometer in different pollution days. The algorithm sensitivity analysis is also provided and discussed. The algorithm can obtain reliable inversion of APSD and AMPs with large radius range.

Retrieving Aerosol Characteristics From the PACE Mission, Part 1: Ocean Color Instrument

NASA’s Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) satellite mission is scheduled to launch in 2022, with the Ocean Color Instrument (OCI) on board. For the first time reflected sunlight from the Earth across a broad spectrum from the ultraviolet (UV: 350 nm) to the short wave infrared (SWIR: 2260 nm) will be measured from a single instrument at 1 km spatial resolution. While seven discrete bands will represent the SWIR, the spectrum from 350 nm to 890 nm will be continuously covered with a spectral resolution of 5 nm. OCI will thus combine in a single instrument (and at an enhanced spatial resolution for the UV) the heritage capabilities of the MODerate resolution Imaging Spectroradiometer (MODIS) and the Ozone Monitoring Instrument (OMI), while covering the oxygen A-band. Designed for ocean color and ocean biology retrievals, OCI also enables continuation of heritage satellite aerosol products and the development of new aerosol characterization from space. In particular the combination of MODIS and OMI characteristics allows deriving aerosol height, absorption and optical depth along with a measure of particle size distribution. This is achieved by using the traditional MODIS visible-to-SWIR wavelengths to constrain spectral aerosol optical depth and particle size. Extrapolating this information to the UV channels allows retrieval of aerosol absorption and layer height. A more direct method to derive aerosol layer height makes use of oxygen A-band absorption methods, despite the relative coarseness of the nominal 5 nm spectral resolution of OCI. Altogether the PACE mission with OCI will be an unprecedented opportunity for aerosol characterization that will continue climate data records from the past decades and propel aerosol science forward towards new opportunities.

The Effect of Electronic Cigarette User Modifications and E-liquid Adulteration on the Particle Size Profile of an Aerosolized Product

Electronic cigarettes (e-cigarettes) are an alternate nicotine delivery system that generate a condensation aerosol to be inhaled by the user. The size of the droplets formed in the aerosol can vary and contributes to drug deposition and ultimate bioavailability in the lung. The growing popularity of e-cigarette products has caused an increase in internet sources promoting the use of drugs other than nicotine (DOTNs) in e-cigarettes. The purpose of this study was to determine the effect of various e-cigarette and e-liquid modifications, such as coil resistance, battery voltage, and glycol and drug formulation, on the aerosol particle size. E-liquids containing 12 mg/mL nicotine prepared in glycol compositions of 100% propylene glycol (PG), 100% vegetable glycerin (VG), or 50:50 PG:VG were aerosolized at three voltages and three coil resistances. Methamphetamine and methadone e-liquids were prepared at 60 mg/mL in 50:50 PG:VG and all e-liquids were aerosolized onto a 10 stage Micro-Orifice Uniform Deposit Impactor. Glycol deposition correlated with drug deposition, and the majority of particles centered between 0.172–0.5 μm in diameter, representing pulmonary deposition. The 100% PG e-liquid produced the largest aerosol particles and the 100% VG and 50:50 PG:VG e-liquids produced ultra-fine particles <0.3 μm. The presence of ultrafine particles indicates that drugs can be aerosolized and reach the pulmonary alveolar regions, highlighting a potential for abuse and risk of overdose with DOTNs aerosolized in an e-cigarette system.

Optical characterization of cloud and aerosol of the temperate zone

Aerosol and cloud optical data of the network AERONET/PHOTONS are in major importance in climate change and air quality studies. Sun photometers allow the determination of cloud and aerosol optical depths and the particle size distribution of aerosol for many sites distributed over large four zones belongs to the temperate areas: Mediterranean, maritime, humid subtropical, and continental and dry. The histograms of cloud occurrence frequencies reveal the dominance variation in the interval (20.100) relating to Stratus and Altostratus, maximum reaches (~ 70%) recorded at eastern Asia (China). For values below 20, the histograms are different from those of Equatorial zone but modeled into two classes, staircase and non-staircase shapes, depending on the weather conditions. The monthly aerosol optical depth averages at 0.5 μm show the highest values in summer, a maximum reach 1.6 at Eastern Asia and coincides with the highest cloud optical depth particularly for Asian sites. Seasonal average of aerosol particle size distribution records larger amplitudes of both fine and coarse modes in the Asian sites especially in the East two to three times higher than those in other zones. The average radius of fine mode is around 0.17 μm expressing high anthropogenic local pollution. The coarse mode around 2.75 μm is very important in Western India with a maximum concentration in summer as seasonal desert dust advections concern.