Traditional in vivo inhalation studies to inform hazard identification and risk assessment are time-intensive and financially expensive. Cell culture models combined with aerosol exposure systems have shown promise as surrogates in screening assays when multiple substances require preliminary information on hazard potential associated with aerosolized materials. This paper presents two different aerosol

Studies on the flow-induced particle resuspension have great significance for engineering applications of many areas, and several established resuspension models have been developed for the analysis of particle resuspension in an atmospheric environment. However, for flow with a non-negligible particle Knudsen number (the ratio between the mean free path of gas and the particle radius), which is commonly

Particle shape strongly influences the diffusion charging of aerosol particles exposed to bipolar/unipolar ions and accurate modeling is needed to predict the charge distribution of non-spherical particles. A prior particle-ion collision kernel βi model including Coulombic and image potential interactions for spherical particles is generalized for arbitrary shapes following a scaling approach that

We investigated a spray-drying aerosol generator that can generate micro-particles at high concentration using an ultrasonic nozzle. Unlike a conventional spray-drying aerosol generator that uses vertical spray with co-current sheath flow, we designed a new aerosol generator by using horizontal spray with co-current sheath flow combined with clean counter flow to increase particle generation efficiency

We report the photodegradation of optically trapped oleic acid droplets by visible light in the absence of additional reactive gaseous species. The temporal evolution of the droplet's chemical composition and size is monitored by Raman spectroscopy and elastic light scattering, respectively. The dependencies on the oxygen amount in the surrounding gas phase (~0–20%), the droplet size (~500–3000 nm

The transport and deposition of inhaled micron particles is largely determined by their inlet conditions, breathing rate, and the individual airway geometry. In this study, helical air-particle flow is introduced which significantly affects the particle dynamics with applications to targeted drug delivery. Specifically, helical flow, which reduces axial momentum, can be controlled by varying the swirl

A differential mobility analyzer along with a centrifugal particle mass analyzer was employed to study the effect of fuel type on effective density for nascent and non-volatile particles generated by a marine diesel engine. The engine was operated at 1500 rpm at loads between 10% and 100%. Three different fuels were evaluated: diesel fuel, distillate marine oil Grade A, and intermediate fuel oil. A

Hygroscopic growth of aerosols plays an important role in the characterization of atmospheric aerosols. Physico-chemical and optical properties of aerosols are dependent on relative humidity (RH) as well as on their size and composition. In this study, scattering enhancement factors, f(RH), for polydispersed aerosols were approximated. f(RH) of ammonium sulfate and ammonium nitrate (AS) and NaCl aerosols

The lack of quantitative risk assessment of airborne transmission of COVID-19 under practical settings leads to large uncertainties and inconsistencies in our preventive measures. Combining in situ measurements and computational fluid dynamics simulations, we quantify the exhaled particles from normal respiratory behaviors and their transport under elevator, small classroom, and supermarket settings

The potential airborne transmission of COVID-19 has raised significant concerns regarding the safety of musical activities involving wind instruments. However, currently, there is a lack of systematic study and quantitative information of the aerosol generation during these instruments, which is crucial for offering risk assessment and the corresponding mitigation strategies for the reopening of these

Structural properties in nonwoven materials, such as porosity and layer thickness, are typically spatially distributed on a micro- and mesoscale. The mesoscale inhomogeneity is visually perceived, inter alia, as the cloudiness of the nonwoven fabric or as inclusions in the bulk material. Differential box counting, which is a fractal based image analysis method, was used to assess the inhomogeneity

In vitro studies are the first step toward understanding the biological effects of particulate matter. As a more realistic exposure strategy than submerged culture approaches, air-liquid interface (ALI) in vitro exposure systems are gaining interest. One challenge with ALI systems is determining accurate particle mass deposition. Although a few commercially available ALI systems are equipped with online

Residential wood combustion, which is characterized by incomplete combustion, is a common source of particulate matter in suburban areas. This study investigated the usability of three different scattering-based particulate matter (PM) sensors and an absorption-based black carbon (BC) sensor in an environment impacted by wood combustion emissions. The measurement campaign, which lasted approximately

Preferential particle orientation has been previously reported for desert dust and attributed on atmospheric electricity (Ulanowski et al., 2007). Depending on its strength, the total electric field within the dust layer can: (a) counteract the gravitational settling of large particles and (b) cause a preferential orientation of the non-spherical particles along the vertical direction (Fucks, 1958;

A recently described DMA designed for high resolution viral particle analysis (Perez-DMA; Perez-Lorenzo et al, 2020) is modified to decrease the relative peak full width at half maximum (FWHM) below previously achieved ≈3.3%. The electrode radii at the outlet slit (R1 = 1.01 cm; R2 = 2 cm) and the working length are almost unchanged (L = 114.9 vs. 116 mm). The laminarization trumpet and the radius

Nasal airway obstruction (NAO) is one of the main problems in the upper part of the human respiratory system. NAO may considerably affect the airflow and the behavior of droplets in the nasal cavity. In the present study, the effect of septal deviation as a special kind of NAO on the deposition and penetration of initially micron-sized inhaled droplets in the nasal cavities of two patients was numerically

The inhalation route has a substantial influence on the fate of inhaled particles. An outbreak of infectious diseases such as COVID-19, influenza or tuberculosis depends on the site of deposition of the inhaled pathogens. But the knowledge of respiratory deposition is important also for occupational safety or targeted delivery of inhaled pharmaceuticals.

The micro-cold spray process produces thick patterned films by impacting powders consisting of nano-to-sub-micron particles at velocities from 300 to over 1400 m/s. This process has been used extensively to produce ceramic films but has been employed only on a very limited basis to produce metallic films. The fine powders used in micro-cold spray are invariably agglomerated to some degree, but the

A method for trace analysis of aerosol mineral components using quantum cascade laser (QCL) based infrared absorption spectroscopy is described. The measurement approach involves: (a) collection of aerosol on a particulate filter; (b) sample treatment using low-temperature oxygenated plasma to minimize the matrix interferences; (c) redeposition of the treated sample as a dried spot for direct-on-filter

Aim There is a need to bridge the data gap concerning the regional deposition of electronic nicotine delivery systems (ENDS) emissions in the airways. The present work aims to experimentally and precisely asses the aerosol regional deposition of ENDS emissions using an ex vivo model of lungs as a complementary approach to a determinist computational model and as an alternative to animal or human in

The development of predictive aerosol dosimetry models has been a major focus of environmental toxicology and pharmaceutical health research for decades. One-dimensional (1D) models successfully predict overall deposition averages but fail to accurately predict local deposition. Computational fluid-particle dynamics (CFPD) models provide site-specific predictions but at a computational cost that prohibits

The synthesis of nanoparticles by reaction of liquid aerosol droplets containing precursors in a flow-through, atmospheric-pressure, non-thermal plasma offers a continuous, scalable, substrate- and stabilizer-free approach for direct deposition into liquids or onto soft substrates. However, the combination of multiphase and non-equilibrium chemistry makes the process complicated and poorly understood

Baghouse filters are widely applied in industrial gas cleaning, for example in waste incineration plants and the cement industry, to meet particle emission standards and for product recovery. The global particle emission of pulse-jet cleaned surface filters is typically monitored end of pipe (e.g. in the stack). Since the particulate matter emission of baghouse filters originates often from leaks and

Laboratory animals are often used to derive health risk from environmental exposure or to assess the therapeutic effect of a drug delivered by inhaled therapy. Knowledge of the in-situ distribution of deposited particles on airway and alveolar surfaces is essential in any assessment of these effects. A unique database including both high-resolution lung anatomy and deposition data in four strains of

The effects of non sphericity and particle orientation on mineral dust gravitational settling are studied for prolate spheroids in the range of Reynolds number up to 100. New drag coefficients for prolate spheroids are defined that take into account the orientation of the particle. The drag coefficients along with the slip correction factors are applied to the momentum equation, which is numerically

Particulate matter (PM) released from industrial emissions could cause health problems, which are strongly associated with the chemical composition of PMs. This study aimed to estimate the unknown contribution of two iron industries using a known iron plant via sensitivity analysis. For this purpose, a comprehensive analysis was carried out on the characteristics of known iron plant, accessible sampling

Filtering the air entering swine farms has significantly reduced the incidence of porcine reproductive and respiratory syndrome virus (PRRSv) infections in Midwestern breeding herds. Despite the significant investment made in installation of air filters, the nature and type of viruses trapped by these filters are not yet clear because of the unavailability of reliable methods to elute and detect these

The impact of moderately absorbing aerosols on the energy budget over Central Europe is discussed, based on experimental observations and numerical simulations obtained for the summer of 2015. Aerosol events, defined as aerosol optical depth (AOD) at 500 nm greater than 0.15, especially in August, are mostly attributed to transport of biomass burning (BB) from Eastern Europe. Shortwave (SW) aerosol

Even with the advance in medical imaging techniques such as CT/MRI, it is still challenging and time-consuming to reconstruct anatomically accurate lung geometries. It is even more challenging to study variability in inhalation dosimetry or pulmonary drug delivery, which requires a large cohort of lung models to ensure statistically significant results. This study used the statistical shape modeling

Accurate predictions of the droplet transport, evolution, and deposition in human airways are critical for the quantitative analysis of the health risks due to the exposure to the airborne pollutant or virus transmission. The droplet/particle-vapor interaction, i.e., the evaporation or condensation of the multi-component droplet/particle, is one of the key mechanisms that need to be precisely modeled

The optical properties of aerosols are investigated using multi-year analysis from the Ilorin AERONET site (8.320° N, 4.340° E) in Nigeria, in tropical West Africa. Characterization at five wavelengths (440, 550, 675, 870 and 1020 nm) were carried out to investigate the absorption and scattering tendencies of aerosol properties at multi-timescale. Results show large aerosol optical thickness (AOT)

Molecular clusters are ubiquitous constituents of the ambient atmosphere, that can grow into larger sizes forming new aerosol particles. The formation and growth of small clusters into aerosol particles remain one of the largest uncertainties in global climate predictions. This has made the modeling of atmospheric molecular clustering into an active field of research, yielding direct molecular level

Many governments have instructed the population to wear simple mouse-and-nose covers or surgical face masks to protect themselves from droplet infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in public. However, the basic protection mechanisms and benefits of these masks remain controversial. Therefore, the aim of this work is to show from a fluid physics point of view

Particle and vapor measurements typically include sampling tubing causing sampling losses therein. Correcting measured concentrations from the sampling losses using the calculated penetration efficiencies of straight tubes is a satisfactory approximation if sub-micrometer particles are of interest. However, in addition to inertial impaction of larger particles, bends in the tubing can cause a significant

The discrete-sectional method to solve the general dynamic equations is a useful tool for the simulation of an evolving aerosol population. This tutorial is intended to equip the reader with the necessary knowledge to implement this method for a single component system. To this end, we provide step-by-step instructions on the construction of a discrete-sectional model, including details on simulation

This technical note documents the fabrication and performance of multiplexed electrospray emitters by rapid laser micromachining. A low cost 1064-nm fiber laser marker system is used to precisely, rapidly and selectively remove materials from a sheet of conductive silicone rubber, which is chemically inert. The laser pulse energy, scanning speed and machining path are judicially chosen to create clean

This study aims to evaluate the filtration performance of three commercially available (3M 8210 respirator, Halyard 48207 surgical mask, and 3M 1820 procedure mask) and two alternative face mask and respirator materials (Halyard H600 sterilization wrap and Cummins EX101) after selected decontamination treatments, including isopropanol (IPA) treatments (soaking or spraying), ultraviolet germicidal irradiation

New Particle Formation (NPF) is regularly observed to occur in heavily polluted Chinese megacities. However, in these NPF events, the survival probability of small clusters into larger aerosol particles is higher than theoretically predicted. One explanation for this could be that the loss rate of clusters due to scavenging by pre-existing particles, which is described by condensation sink, is lower

Particle size distributions (PSDs) of engine blow-by aerosol are commonly obtained with an optical particle counter (OPC), but representative measurements are challenging due to high number concentrations, elevated temperatures, presence of saturated vapor, as well as unsteady flow conditions. A comprehensive study of blow-by aerosol sampling/conditioning and OPC performance in such an environment

Transmissivity and absorptivity measurements were carried out simultaneously in the visible (wavelength of 532 nm) at laboratory conditions using particle-laden filters obtained from a three-wavelength particle/soot absorption photometer (PSAP). The particles were collected on filters from wildland fires over the Pacific Northwest during the Department of Energy Biomass Burning Observation Project

3D printers have been widely used as a tool for prototype manufacturing in industries, schools, and homes. During operation, 3D printers emit ultrafine particles that could be inhaled by the user and induce adverse health effects. Thus, exposure to ultrafine 3D-printing generated particles has drawn the attention of occupational and environmental health researchers. In this study, a recently developed

Black carbon, as a series of light-absorbing carbonaceous material, contributes significantly to current global warming. Black carbon has always been considered a product of incomplete combustion of fossil fuels and vegetation. In the road transport sector, combustion exhaust is thought to be the primary source of black carbon. This study uses a pin-on-disc tribometer to simulate automotive disc brake

Several decades of developing laser induced incandescence (LII) as a combustion diagnostic have led to great advances in understanding soot formation. The bulk of diagnostic development has focused on time-resolved LII (TiRe-LII) where heating of soot particles using a laser, and the subsequent particle cooling, can be measured and matched to a model to determine soot primary particle size. These models

Bipolar charging and neutralization of aerosol particles below 100 nm in a laminar flow tube with a uniform generation rate of mass- and mobility-distributed heterogeneous ions has been studied theoretically, and compared to the case of homogeneous, monodisperse ions. Two types of homogeneous ions have been examined: type-I, having the arithmetic mean mass and mobility of the heterogeneous ions; and

Interest in understanding gas-to-particle phase transformation in several disciplines such as atmospheric sciences, material synthesis, and combustion has led to the development of several distinct instruments that can measure the particle size distributions down to the sizes of large molecules and molecular clusters, at which the initial particle formation and growth takes place. These instruments

Aerosols were produced from a MOX (Mixed Oxide of uranium and plutonium) sample by laser heating up to 4000 K under atmospheric conditions. They were collected with a cascade impactor as function of their aerodynamic size, and studied by SEM, EDS, TEM, EELS, SAED and ICPMS. The uranium and plutonium concentrations were related to the aerosol morphology, size and formation temperature. A clear decrease

Ultrafine particle behavior in electro-hydrodynamic (EHD) flow induced by corona discharge is studied experimentally and numerically. The EHD flow serves as a primary particle aspiration/sampling mechanism, the collector does not require any additional flow generation. Multiphysics numerical model couples the ion transport equation and the Navier-Stokes equations (NSE) to solve for the spatiotemporal

Electrical mobility and mass of atmospheric ions are of great importance, since both properties jointly determine their charging states. In this work, different carrier gases of bottle N2, bottle air, and particle-free lab air were passed through a TSI® soft X-ray aerosol neutralizer to produce both positive and negative ions. The electrical mobilities and mass-to-charge ratios of these ions were measured

Quantification of airway deposition of aerosol particles is essential for the assessment of health risks of detrimental particles. Knowledge of deposition distribution is important also in the case of treatment with aerosolised drugs. It is also worth considering that deposition of inhaled particles in severe asthmatics can be different from the deposition in healthy subjects due to the modified breathing

It has been confirmed that the coronavirus disease 2019 (COVID-19) can transmit through droplets created when an infected human coughs or sneezes. Accordingly, 1.83-m (6-feet) social distancing is advised to reduce the spread of the disease among humans. This is based on the assumption that no air circulation exists around people. However, it is not well investigated whether the ambient wind and relative

An analysis is presented of the evolution of a narrow ion beam, produced for instance by an electrospray source, in ambient pressure air. To minimize beam broadening, an intense axial electric field E is externally imposed. Still, radial beam broadening due to the ionic diffusivity D and space charge must be accounted for. Ignoring axial contributions of diffusion and space charge, a simple second