Aerosol Science And Technology[JOURNAL]
Sun
138 papers
Enhanced vapor wall loss of intermediate volatility alcohols at elevated relative humidity.
Docherty KS, Schervish M, Yang D … +4 more , Jerden M, Olson DA, Jaoui M, Lewandowski M
Aerosol Sci Technol · 2026 Apr · PMID 42306653 · Full text
A series of experiments was conducted to investigate the role of water vapor in enhancing vapor wall loss of intermediate volatility alcohols ranging from C-C terminal aliphatic alcohols, aromatic alcohols, and diols. In...
A series of experiments was conducted to investigate the role of water vapor in enhancing vapor wall loss of intermediate volatility alcohols ranging from C-C terminal aliphatic alcohols, aromatic alcohols, and diols. In the first of two types of experiments, a constant alcohol concentration (2.48 ± 1.48 ppmv) was introduced along with a dilution reference (DR) while chamber relative humidity (RH) was varied from dry (~3%) to a maximum of ~40%. Alcohol gas phase concentrations in the inlet manifold and chamber were monitored throughout each experiment by on-line gas chromatography with flame ionization detection. Wall loss was parameterized in each case using the dilution ratio (i.e., ratio of inlet to chamber concentration) for the alcohol relative to that for the DR. Dilution ratios uniformly increase across the range of investigated alcohols as chamber RH is increased but varied considerably among the different alcohols. In the second type of experiment, RH was held constant and chamber concentrations of 1-nonanol were varied as the chamber was spun up to steady state and back down. The rate of decay of 1-nonanol concentration differs between dry and ~25% suggesting that RH can also influence reversibility of RH-enhanced wall losses. Finally, a model was used to simulate wall loss processes for each investigated alcohol. Measurements and model output were overall in close agreement indicating that gas-wall partitioning is strongly linked to RH.
Organic components modulate the morphology of respirable aerovirology-relevant aerosols.
Sapkota D, Guo Y, Chakraborty A … +5 more , Hu J, Xie H, Wu I, Kim MJ, Ouyang H
Aerosol Sci Technol · 2026 Mar · PMID 42266406 · Full text
Airborne transmission of viruses occurs aerosol particles, whose morphology provides insights into the microenvironments that viruses experience. Aerosol morphology includes particle size, shape, phase state, and chemic...
Airborne transmission of viruses occurs aerosol particles, whose morphology provides insights into the microenvironments that viruses experience. Aerosol morphology includes particle size, shape, phase state, and chemical homogeneity, yet systematic studies remain limited. Here, we characterized model bioaerosol morphologies generated from (1) NaCl-organic two-component mixtures, (2) common cell culture media, and (3) artificial respiratory fluids. Particles were collected using a virtual impactor and Andersen cascade impactor and analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Results show that organic components modulate the morphology: dipalmitoylphosphatidylcholine (DPPC) promotes organic-inorganic phase separation while proteins prohibit formation of large crystals and leads to better mixing among components. At 30% RH with a drying period of 10 s, most aerosols appeared desiccated, though NaCl-glucose, DMEM complete media and artificial saliva with mucin remained semi-solid or gel-like. Among all formulations examined, EMEM complete media and artificial saliva (non-mucin) show a size-dependent morphology. Our study demonstrates how chemical composition and size alter surrogate bioaerosol phase (semi-solid or solid) and morphology and provides new insights into the microenvironment of aerosol particles for aerovirology investigations.
Development of a Platform for Airborne Virus Detection by Interfacing RT-LAMP Assay with a Condensational Growth Collector.
Shirkhani A, Jansen M, Alipanahrostami M … +9 more , Manzanas C, Shankar SN, Vass WB, Chien CH, Washeem M, O'Connor A, Lednicky JA, Fan ZH, Wu CY
Aerosol Sci Technol · 2026 · PMID 41918788 · Full text
Collection and identification of airborne viruses conventionally involve two separate processes: air sampling in the field and subsequent laboratory-based detection and analyses. They are time-consuming, which delays ear...
Collection and identification of airborne viruses conventionally involve two separate processes: air sampling in the field and subsequent laboratory-based detection and analyses. They are time-consuming, which delays early warnings and hinders timely implementation of public health countermeasures. virus detection methods that enable preliminary identification at the sampling site can improve timeliness, eliminating the need for sample transport and allowing rapid decision-making. Herein, we developed and evaluated an integrated system that connects a water condensation-based aerosol collector called VIVAS with an detection platform known as VLEAD. We designed and fabricated an interface to serve both as the VIVAS' collection chamber and as a conduit for fluid transfer into the VLEAD. The design achieved over 90% collection efficiency for particles ≥3 μm after computational fluid dynamics simulation optimization, and experimental testing confirmed a physical collection efficiency of approximately 95%. When exposed to lab-generated aerosols containing human coronavirus OC43 (HCoV-OC43), the system achieved a 100% detection rate for samples containing > 10 genome equivalents (GE) of virus per sample (4-5 GE/μL, triplicates), verified by RT-qPCR. The integrated system replaced the standard Petri dish in the commercially available VIVAS and enabled seamless transfer for RT-LAMP-based detection. The limit of detection was comparable to the level at which viruses such as SARS-CoV-2 have been collected using the VIVAS during environmental sampling reported in other studies. That performance demonstrated strong potential for rapid, detection of airborne coronaviruses and potentially other viruses in field settings or public spaces during respiratory viral disease outbreaks.
Detection of SARS-CoV-2 RNA on air purifier filters in university spaces without symptomatic or confirmed cases.
Li J, Bot M, Liu X … +3 more , Yao Y, Ophoff RA, Zhu Y
Aerosol Sci Technol · 2025 Dec · PMID 41613914 · Full text
Understanding the seasonality and prevalence of respiratory viruses in indoor environments is essential for protecting public health in the post-pandemic era. This study investigated the presence of airborne SARS-CoV-2 i...
Understanding the seasonality and prevalence of respiratory viruses in indoor environments is essential for protecting public health in the post-pandemic era. This study investigated the presence of airborne SARS-CoV-2 in university indoor spaces where no symptomatic or confirmed positive individuals were supposed to be present. A total of 127 high-efficiency particulate air (HEPA) filter samples were analyzed from air purifiers installed in classrooms, conference rooms, and a community room within a university building across different seasons from Fall 2022 to Summer 2023. Viral RNA was extracted and quantified using RT-qPCR for each sample. SARS-CoV-2 RNA was detected in 21% of the samples, with the positivity rate varying significantly by room type but not by season. Among the 27 positive samples, viral RNA concentrations were significantly higher in fall-winter compared to summer, with no significant differences across room types. Additionally, respiratory syncytial virus (RSV) and influenza A virus (IAV) were detected in far fewer samples (positive rates: 2% and 4%, respectively) and at much lower concentrations than SARS-CoV-2. These findings provide evidence of the potential for airborne SARS-CoV-2 transmission in shared indoor spaces, even in the absence of known infectious individuals. They also suggest that SARS-CoV-2 may circulate in each season, underscoring the continued need for interventions to reduce indoor viral exposure.
The impact of particle size on PFAS concentrations in dust from homes in North Carolina and New York and implications for exposure.
Eichler CMA, Rawat MS, Chang NY … +6 more , Brown E, Fernando S, Holsen TM, Morrison GC, Ferro AR, Turpin BJ
Aerosol Sci Technol · 2026 · PMID 41438934 · Full text
Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals and ubiquitously present in the environment, including in homes. The two major exposure pathways for PFAS indoors are inhalation and accidental ingest...
Per- and polyfluoroalkyl substances (PFAS) are manufactured chemicals and ubiquitously present in the environment, including in homes. The two major exposure pathways for PFAS indoors are inhalation and accidental ingestion of house dust; however, the influence of dust particle size on PFAS exposure is not well understood to date. Thus, we are aiming to better understand the relationship between dust particle size and PFAS concentrations. We collected dust from 10 homes in North Carolina and seven homes in New York, sieved the dust into multiple size fractions ranging from <63 μm to <2,000 μm, and used targeted methods to analyze the fractions for PFAS. We found that many neutral PFAS are significantly ( < 0.05) and negatively correlated with dust particle size (mean Pearson correlation coefficient to -0.90), i.e., higher concentrations were found in the smaller size fractions. This suggests that neutral PFAS concentrations in dust are primarily influenced by partitioning to the dust particles from the gas phase. On the other hand, several perfluoroalkyl acids showed no clear or positive correlations between particle size and concentration (mean Pearson to 0.65), suggesting that additional migration pathways contribute preferentially to the larger size fractions, such as abrasion of fibers from upholstery. Dust-air partition coefficients, , derived for neutral PFAS for a subset of homes reflect this observation, with higher values found for smaller dust size fractions compared to larger size fractions. This work highlights the importance of the choice of size fraction when analyzing PFAS in dust and for exposure assessments.
Sources and aging of individual atmospheric particles in New York City: Integrating novel functional group data from optical photothermal spectroscopy with elemental and mass spectrometry data.
Xiao Y, Costa EJ, He X … +8 more , Rogers MJ, Mirrielees JA, Hass-Mitchell TN, Joo T, Nault BA, Gentner DR, O'Brien RE, Ault AP
Aerosol Sci Technol · 2025 Sep · PMID 41103308 · Full text
Elevated concentrations of fine particulate matter (PM, particles < 2.5 m) lead to negative health outcomes in urban areas, such as New York City (NYC). The sources of particles contributing to PM in NYC are variable and...
Elevated concentrations of fine particulate matter (PM, particles < 2.5 m) lead to negative health outcomes in urban areas, such as New York City (NYC). The sources of particles contributing to PM in NYC are variable and complex due to the range of primary anthropogenic and biogenic emissions, as well as secondary aerosol formation (i.e., aging) from gaseous precursors. To improve understanding of the contributors to PM, single particle microspectroscopy uses chemical fingerprints to identify sources and the extent of aging, but few studies have integrated multiple microspectroscopy methods to understand PM in NYC. Herein, we focus on a recently-developed form of microspectroscopy that can measure atmospherically-sized particles (>~0.8 m), optical photothermal infrared (O-PTIR). We compare O-PTIR to existing microspectroscopy methods [Raman, fluorescence, and energy dispersive X-ray (EDX)] to study sources and aging of the complex NYC aerosol based on functional group and elemental information, which we also relate to bulk mass spectrometry methods. Single particle data shows submicron aerosol composition dominated by carbonaceous particles that fluoresce mixed with ammonium and sulfate, with a range of oxidized organic functional groups observed. At larger sizes, more primary sources (salts, dust, and biological) were observed, with nitrate being the dominant secondary anion. Collectively, the results from OPTIR and other instruments across case-study days reveal variations in sources and aging, with greater variability at larger diameters. Demonstrating the potential of O-PTIR when combined with the other methods to provide data that is important for improving air quality in urban megacities.
Cellular responses of lung cells cultured at an Air-liquid Interface are influenced by spatial nanoparticle deposition patterns in an aerosol exposure system.
Shankar SN, O'Connor A, Mital K … +10 more , Zhang Y, Theodore A, Shirkhani A, Amanatidis S, Lewis GS, Fernandez AE, Tilly TB, Schmid O, Sabo-Attwood T, Wu CY
Aerosol Sci Technol · 2025 · PMID 41050869 · Full text
The deposition of inhaled particles is typically highly localized in both the bronchial and alveolar region of the lung displaying spot-like, line-like and other deposition patterns. However, knowledge is very limited on...
The deposition of inhaled particles is typically highly localized in both the bronchial and alveolar region of the lung displaying spot-like, line-like and other deposition patterns. However, knowledge is very limited on how different deposition patterns may influence downstream cellular responses. In this study, the Dosimetric Aerosol Inhalation Device (DAVID) was used for dose-controlled deposition of cupric oxide nanoparticles (CuONPs) in four different patterns (i.e., spot, ring, line and circle) on human alveolar A549 cells cultured at an air-liquid interface (ALI). After CuONP deposition (<15 min) and a 24 h incubation phase, cell viability, apoptotic / necrotic cell count, and gene expressions were measured. At the lowest dose of ~5 μg/cm, the line pattern resulted in the lowest viability of cells (57%), followed by the spot pattern (85%) while the ring and circle patterns exhibited >90% viability, compared to the particle free air control. At the highest dose of ~20 μg/cm, the viability reduced to 44%-60% for all patterns. Also, the gene profile was found to depend on deposition pattern. The results demonstrate that the deposition pattern is a critical parameter influencing cellular response, thus an important parameter to consider in toxicity and drug delivery studies. Furthermore, the ability of DAVID to control the delivery of aerosolized particles in various deposition patterns was demonstrated, which enables implementation of nonhomogeneous particle deposition patterns that mimic real-life human inhalation exposures in future toxicology studies.
An affordable, water-based, community condensation particle counter.
Hering S, Amanatidis S, Eiguren-Fernandez A … +3 more , Lewis GS, Spielman SR, Pariseau D
Aerosol Sci Technol · 2025 May · PMID 40979442 · Full text
A "Community Condensation Particle Counter" (cCPC) has been developed to provide an affordable monitor of airborne particle number concentrations. The cCPC is an expansion-type condensation particle counter that incorpor...
A "Community Condensation Particle Counter" (cCPC) has been developed to provide an affordable monitor of airborne particle number concentrations. The cCPC is an expansion-type condensation particle counter that incorporates single particle counting to yield a direct measurement of number concentration. Particle number concentrations are derived from the detection of individual droplets exiting the cell during the expansion, combined with the pressure readings and the physical volume of the particle cell. Modeling and experiment confirm detection of particles as small as 4 nm, with >95% detection above 20 nm. For 12 days of ambient sampling two collocated cCPCs exhibit a pooled standard deviation of 3.5%. Comparison to a pair of benchtop instruments (ADI MAGIC CPCs) yields a correlation of R=0.98 and a regression slope of 1.1. Laboratory studies at concentrations higher than 3×10 cm for both sulfate and dioctyl sebacate show equally reduced response when compared to a versatile water CPC, but this was not observed in ambient aerosol sampling. Further research will be needed to resolve this discrepancy.
Application and validation of a wearable monitor for assessing time- and location-resolved exposures to particulate matter in California's Central Valley.
Li X, Tryner J, Young BN … +10 more , Ramirez LH, Phillips M, WeMott S, Erlandson G, Kuiper G, Dean D, Martinez N, Sanpedro L, Magzamen S, Volckens J
Aerosol Sci Technol · 2025 Oct · PMID 40958982 · Full text
Reliable assessment of personal exposure to air pollution remains a challenge due to the limitations of monitoring technology. Recent technology developments, such as reductions in the size and cost of samplers as well a...
Reliable assessment of personal exposure to air pollution remains a challenge due to the limitations of monitoring technology. Recent technology developments, such as reductions in the size and cost of samplers as well as incorporation of continuous sensors for location, activity, and exposure (i.e., global positioning systems [GPS], accelerometers, and low-cost pollutant sensors), have advanced our ability to assess personal exposure to air pollution. This study evaluated the upgraded Ultrasonic Personal Aerosol Sampler (UPAS v2.1 PLUS) as a tool for quantifying time-integrated indoor and personal exposure to particulate matter (PM) and black carbon (BC) among a panel of participants in California's Central Valley and exploring personal exposures in different microenvironments using time/location-resolved PM data. Three field campaigns demonstrated that filter-derived PM, PM, PM BC, and PM BC concentrations measured using the UPAS were linear, unbiased, and precise compared to those measured using conventional personal sampling equipment. Time-resolved PM, GPS, and light intensity data from the UPAS allowed for personal PM exposure assessment across microenvironments. The majority of daily PM exposure occurred inside the home. Participants with higher out-of-home PM exposures received those exposures primarily in agricultural and in-transit environments, in accordance with their self-reported occupational exposures. This study demonstrated the UPAS v2.1 PLUS is a reliable and valid tool for characterizing indoor air pollution and personal exposures in both temporal and spatial dimensions. Its enhanced capabilities should reduce the burden of personal activity logging in the field and enable accurate and precise estimation of exposures for epidemiological and community-based research.
Occupational exposure monitoring of airborne respiratory viruses in outpatient medical clinics.
Vass WB, Shirkhani A, Washeem M … +11 more , Shankar SN, Zhang Y, Moquin TL, Messcher RL, Jansen MD, Clugston JR, Walser MP, Yang Y, Lednicky JA, Fan ZH, Wu CY
Aerosol Sci Technol · 2024 Oct · PMID 40678809 · Full text
Exposure to airborne respiratory viruses can be a health hazard in occupational settings. In this study, air sampling was conducted from January to March 2023 in two outpatient medical clinics-one primary care clinic and...
Exposure to airborne respiratory viruses can be a health hazard in occupational settings. In this study, air sampling was conducted from January to March 2023 in two outpatient medical clinics-one primary care clinic and one clinic dedicated to the diagnosis and treatment of respiratory illnesses-for the purpose of assessing airborne respiratory virus presence. Work involved the operation of a BioSpot-VIVAS as a stationary air sampler and deployment of NIOSH BC-251 bioaerosol samplers as either stationary devices or personal air samplers worn by staff members. Results were correlated with deidentified clinical data from patient testing. Samples from seven days were analyzed for SARS-CoV-2, influenza A H1N1 and H3N2 viruses, and influenza B Victoria- and Yamagata-lineage viruses, with an overall 17.5% (17/97) positivity rate. Airborne viruses predominated in particles of aerodynamic diameters from 1-4 μm and were recovered in similar quantities from both clinics. BC-251 samplers (17.4%, 15/86) and VIVAS (18.2%, 2/11) collected detectable viruses at similar rates, but more numerous BC-251 samplers provided greater insight into virus presence across clinical spaces and job categories. 60% of samples from reception areas contained detectable virus, and exposure to significantly more virus (p = 0.0028) occurred at reception desks as compared to the "mobile" job categories of medical providers and nurses. Overall, this study provides valuable insights into the impacts of hazard mitigation controls tailored to reducing respiratory virus exposure and highlights the need for continued diligence toward exposure risk mitigation in outpatient medical clinics.
3D printed micro-cyclones with improved geometries for low-cost aerosol size separation.
Goderis D, Xiao Y, Alotbi A … +4 more , Ahtsham A, Dvonch JT, Mason AJ, Ault AP
Aerosol Sci Technol · 2025 · PMID 40248517 · Full text
The impact of suspended particles on health, climate, and industrial applications is highly size-dependent. Thus, regulations are typically based on particles with diameters below a specific size, such as particulate mat...
The impact of suspended particles on health, climate, and industrial applications is highly size-dependent. Thus, regulations are typically based on particles with diameters below a specific size, such as particulate matter less than 2.5 μm (PM). For over a century, cyclones have been employed to isolate particles below a certain diameter by removing large particles from a gas stream, but cyclones are typically relatively large, heavy, and expensive to fabricate compared to objects made with low-cost 3-dimensional (3D) printers. Herein, we present one-piece 3D-printed micro-cyclones (PM and PM) to isolate particles smaller than a specific diameter. The collection efficiencies and 50% cut-off diameters (d) of multiple cyclones were evaluated with both monodisperse and polydisperse standards ranging from 0.1 to 3 μm, as well as ambient aerosol. By altering the inlet orientation relative to the micro-cyclone centerline (orthogonal, 50% offset, and fully offset), we show that shifting the inlet radially outward increased the steepness of the transmission curve resulting in a sharper cut-point. The d also decreased below the designed for diameter, (PM = 1.4, 1.0, and 0.9 μm; PM = 3.2, 2.0, 1.9 μm), which was attributed to imperfect models, internal surface roughness, and print errors versus machining. These single piece, 3D-printed cyclones provide a cheaper (< $1), faster, and more accessible approach to manufacture micro-cyclones for use in a range of aerosol applications.
The microphysics of surrogates of exhaled aerosols from the upper respiratory tract.
Tian J, Alexander RW, Hardy DA … +4 more , Hilditch TG, Oswin HP, Haddrell AE, Reid JP
Aerosol Sci Technol · 2024 Apr · PMID 40236828 · Full text
Airborne transmission plays a significant role in the transmission of respiratory diseases such as COVID-19, for which the respiratory aerosol droplets are responsible for the transportation of potentially infectious pat...
Airborne transmission plays a significant role in the transmission of respiratory diseases such as COVID-19, for which the respiratory aerosol droplets are responsible for the transportation of potentially infectious pathogens. However, the aerosol physicochemical dynamics during the exhalation process are not well understood. The representativeness of respiratory droplet surrogates of exhaled aerosol and suspension media for aerosols currently used for laboratory studies remains debated. Here, we compare the evaporation kinetics and equilibrium thermodynamics of surrogate respiratory aerosol droplets including sodium chloride, artificial saliva (AS) and Dulbecco's modified Eagle's medium (DMEM) by using the Comparative Kinetics Electrodynamic Balance. The potential influences of droplet composition on aerosol hygroscopic response and phase behavior, and the influence of mucin are reported. The equilibrium hygroscopicity measurement was used to verify and benchmark the prediction of evaporation kinetics of complex solutions using the Single Aerosol Particle Drying Kinetics and Trajectory model. We show that the compositionally complex culture media which differs from sodium chloride and artificial saliva (mucin-free solutions). The DMEM evaporation dynamics contained three distinctive phases when drying at a range of humidities, including a semi-dissolved phase when evaporating at the environmental humidity range. The effect of mucin on droplet evaporation and phase behavior at low RH were compared between AS and DMEM solutions. In both cases, mucin delayed the crystallization time of the droplets, but it promoted phase change (from homogenous to semi-dissolved/spherical with inclusions) to occur at higher water activities.
Dust resuspension from the splash of a falling powder: A numerical aerodynamic simulation of a pellet falling onto a powder monolayer.
Turkevich LA, Chen H, Jog MA
Aerosol Sci Technol · 2025 · PMID 40160717 · Full text
A falling powder can generate a dust cloud from its interaction with the ambient air and from its splash onto a substrate. This article reports the results of a numerical simulation study, which attempts to model this se...
A falling powder can generate a dust cloud from its interaction with the ambient air and from its splash onto a substrate. This article reports the results of a numerical simulation study, which attempts to model this second process. We argue that the dust cloud arises from the aerodynamic resuspension of previously deposited small particles. The agglomerated falling powder is modeled as a falling pellet disk impacting a surface covered with a monolayer of previously deposited particles. The Reynolds number of the air flow in the vicinity of the impacting pellet is Re ~ 1860, so the air flow is modeled as laminar and incompressible. The dust particles are incorporated a Lagrangian multiphase treatment. The sudden deceleration of the disk sheds an aerodynamic vortex, which suspends particles from the monolayer. Characteristics of the dust cloud (average and maximum height and radius) are tracked; these are conveniently summarized by following the trajectory of the dust cloud centroid. The probability of aerosolization decreases with distance from the impacted pellet. The centroid trajectory is studied as a function of dust particle size. The model is relatively insensitive to disk radius and thickness. More realistic modeling of dust clouds generated by the splash of falling powders will require a statistical analysis of aggregate size and location, as well as the inclusion of interparticle and particle-surface interactions.
Influence of relative humidity and aging on the optical properties of organic aerosols from burning African biomass fuels.
McRee MM, Moschos V, Fiddler MN … +3 more , Massabò D, Surratt JD, Bililign S
Aerosol Sci Technol · 2025 · PMID 40144025 · Full text
Biomass burning (BB) is a major source of atmospheric fine carbonaceous aerosols, which play a significant, yet uncertain, role in modulating the Earth's radiation balance. However, accurately representing their optical...
Biomass burning (BB) is a major source of atmospheric fine carbonaceous aerosols, which play a significant, yet uncertain, role in modulating the Earth's radiation balance. However, accurately representing their optical properties in climate models remains challenging due to factors such as particle size, mixing state, combustion type, chemical composition, aging processes, and relative humidity (RH). In our study, we investigated BB organic-rich aerosols generated from smoldering sub-Saharan African biomass fuels. Fuel samples were collected in Africa and aerosols generated in the laboratory. We quantified key optical parameters, including mass cross-sections for extinction (2.04 ± 0.32 - 15.5 ± 2.48 m/g), absorption (0.04 ± 0.01-0.3 ± 0.1 m/g), and scattering (1.9 ± 0.68-15.3 ± 5.5 m/g). Wavelength-dependent properties were used to determine absorption and scattering Ångström exponents. The single scattering albedo of these aerosols ranged from 0.8 ± 0.03 to 1.0 ± 0.04 and we observed a wavelength-dependent behavior. Extinction emission factors were determined at a wavelength of 550 nm, with values ranging from 42 ± 5 to 293 ± 32 m/kg. Notably, optical properties exhibited fuel-type dependence, with differences observed between hardwood samples and other fuels, such as grass and animal dung. Aging increased mass extinction and scattering cross-sections at 550 nm, while humidity had the opposite effect across all fuels. Nitrate radical oxidation, both in photo and dark aging conditions, also influenced these properties. The findings are expected to close the gap in our understanding of optical properties of BB aerosol emissions in one of the least studied regions of the world - Africa - providing information to climate and air quality models for the region.
An innovative approach to characterizing the refractive indices and effective densities of internally mixed light-absorbing aerosol particles.
Lawson GR, Chen SX, Collins G … +6 more , Lawson N, Szpek K, Bowles J, Allan J, Langridge JM, Cotterell MI
Aerosol Sci Technol · 2025 · PMID 41952770 · Full text
To improve our understanding of how light interacts with internally mixed light absorbing aerosol particles, we establish an integrated measurement platform enabling concurrent determinations of the complex refractive in...
To improve our understanding of how light interacts with internally mixed light absorbing aerosol particles, we establish an integrated measurement platform enabling concurrent determinations of the complex refractive indices ( = + ) and effective densities () of aerosol particles. Cavity ring-down and photoacoustic spectroscopy are used to measure the extinction and absorption cross-sections, respectively, for aerosol particles classified by their aerodynamic size using the Cambustion Aerodynamic Aerosol Classifier. We report measurements on laboratory generated aerosol particles composed of ammonium sulfate (non-absorbing inorganic), sucrose (non-absorbing organic), nigrosin (strong light-absorbing organic), and two-component particles comprised of internal mixtures of nigrosin with each non-absorbing species. The accuracy and precision of measured cross-sections and retrieved are assessed, and we demonstrate improved precision in these quantities retrieved for aerodynamically classified particles compared to approaches that utilize mobility classification. We show that accurate knowledge of the variations in with mixture composition are essential for predicting for internally mixed particles using mixing rules. For organic mixtures of sucrose and nigrosin, and are predicted accurately by mass fraction weightings of pure component values, and ideal mixing between components is observed. For organic-inorganic mixtures of nigrosin with ammonium sulfate, varies non-linearly with composition and cannot be predicted by linear mixing rules. Instead, a mole fraction weighting of molar refraction, incorporating changes in particle mass density on mixing, is needed. These evaluations of refractive index models provide useful insights for researchers developing atmospheric models or inferring particle physicochemical properties from optical spectroscopy data.
Nanofibrous filters: A promising solution for the efficient capture of polydisperse viral aerosols.
Fadeev A, Crown K, Kinahan S … +2 more , Lucero G, Salkovskiy Y
Aerosol Sci Technol · 2025 · PMID 39991511 · Full text
This study investigates the effectiveness of electrospun nanofibrous filters in capturing polydisperse virus-containing aerosols and the subsequent release of viruses, in comparison with standard commercial filters used...
This study investigates the effectiveness of electrospun nanofibrous filters in capturing polydisperse virus-containing aerosols and the subsequent release of viruses, in comparison with standard commercial filters used in respirators, military gas masks, and devices for airborne virus sampling. We assessed the performance of these filters in capturing and releasing polydisperse aerosols containing MS2 bacteriophage, as well as in their ability to filter monodisperse dioctyl phthalate aerosols measuring 0.185 μm and 0.3 μm in diameter. Our findings indicate that nanofibrous filters provide superior filtration efficiency for monodisperse aerosols, achieving a reduction in the concentration of penetrating aerosols by 2-3 orders of magnitude compared to their commercial counterparts. However, this enhanced efficiency is accompanied by a higher pressure drop and a lower quality factor, underscoring the need for further improvements. Additionally, our research confirms the feasibility of producing aligned nanofibers via multiple-jet needleless electrospinning, though alignment did not significantly impact filtration efficiency. Nanofibrous filters demonstrated filtration efficiency for aerosolized virus-containing particles that was comparable to or better than that of commercial filters. Notably, certain nanofibrous filters exhibited exceptionally low rates of viral aerosol capture and release, indicating a potential for virus neutralization. Moreover, filters made from water-soluble electrospun polyvinylpyrrolidone significantly outperformed those made from gelatin in terms of viral particle release, underscoring the potential of water-soluble electrospun materials in improving viral particle collection. Overall, our study highlights the significant promise of electrospun nanofibers in public health, especially in enhancing defenses against the transmission of viral aerosols.
Concentrating viable airborne pathogens using a virtual impactor with a compact water-based condensation air sampler.
Vass WB, Shankar SN, Lednicky JA … +5 more , Alipanah M, Stump B, Keady P, Fan ZH, Wu CY
Aerosol Sci Technol · 2024 · PMID 39492847 · Full text
Pathogens can be collected from air and detected in samples by many methods. However, merely detecting pathogens does not answer whether they can spread disease. To fully assess health risks from exposure to airborne pat...
Pathogens can be collected from air and detected in samples by many methods. However, merely detecting pathogens does not answer whether they can spread disease. To fully assess health risks from exposure to airborne pathogens, the infectivity of those agents must be assessed. Air samplers which operate by growing particles through water vapor condensation and subsequently collecting them into a liquid medium have proven effective at conserving the viability of microorganisms. We present a study that assessed performance improvement of one such sampler, BioSpot-GEM, gained by augmenting it with an upstream virtual impactor (VI) designed to concentrate particles in aerosols. We demonstrate that such an integrated unit improved the collection of live by a median Concentration Factor ( ) of 1.59 and increased the recovery of viable human coronavirus OC43 (OC43) by a median of 12.7 as compared to the sampler without the VI. Our results also show that OC43 can be concentrated in this way without significant loss of infectivity. We further present that the small BioSpot-GEM bioaerosol sampler can collect live at an efficiency comparable to the larger BioSpot-VIVAS bioaerosol sampler. Our analyses show potential benefits toward improving the collection of viable pathogens from the air using a more portable water-based condensation air sampler while also highlighting challenges associated with using a VI with concentrated bioaerosols. This work can aid further investigation of VI usage to improve the collection of pathogens from air ultimately to better characterize health risks associated with airborne pathogen exposures.
Compact, high-flow, water-based, turbulent-mixing, condensation aerosol concentrator for collection of spot samples.
Zervaki O, Dionysiou DD, Kulkarni P
Aerosol Sci Technol · 2024 · PMID 39376592 · Full text
A new high-flow, compact aerosol concentrator, using rapid, turbulent mixing to grow aerosol particles into droplets for dry spot sample collection, has been designed and tested. The "TCAC (Turbulent-mixing, Condensation...
A new high-flow, compact aerosol concentrator, using rapid, turbulent mixing to grow aerosol particles into droplets for dry spot sample collection, has been designed and tested. The "TCAC (Turbulent-mixing, Condensation Aerosol Concentrator)" is composed of a saturator for generating hot vapor, a mixing section where the hot vapor mixes with the cold aerosol flow, a growth tube where condensational droplet growth primarily occurs, and a converging nozzle that focuses the droplets into a beam. The prototype concentrator utilizes an aerosol sample flow rate of 4 L min. The TCAC was optimized by varying the operating conditions, such as relative humidity of the aerosol flow, mixing flow ratio, vapor temperature, and impaction characteristics. The results showed that particles with a diameter ≥ 25 nm can be grown to a droplet diameter > 1400 nm with near 100% efficiency. Complete activation and growth were observed at relative humidity ≥ 25% of the aerosol sample flow. A consistent spot sample with a diameter of (the diameter of a circle containing 90% of the deposited particles) was obtained regardless of the aerosol particle diameter ( ). For fiber counting applications using phase contrast microscopy, the TCAC can reduce the sampling time, or counting uncertainty, by two to three orders of magnitude, compared to the 25-mm-filter collection. The study shows that the proposed mixing-flow scheme enables a compact spot sample collector suitable for handheld or portable applications, while still allowing for high flow rates.
Fundamentals of low-cost aerosol sensor design and operation.
Ouimette J, Arnott WP, Laven P … +6 more , Whitwell R, Radhakrishnan N, Dhaniyala S, Sandink M, Tryner J, Volckens J
Aerosol Sci Technol · 2024 · PMID 38993374 · Full text
Most evaluations of low-cost aerosol sensors have focused on their measurement bias compared to regulatory monitors. Few evaluations have applied fundamental principles of aerosol science to increase our understanding of...
Most evaluations of low-cost aerosol sensors have focused on their measurement bias compared to regulatory monitors. Few evaluations have applied fundamental principles of aerosol science to increase our understanding of how such sensors work and could be improved. We examined the Plantower PMS5003 sensor's internal geometry, laser properties, photodiode responses, microprocessor output, flow rates, and response to mono- and poly-disperse aerosols. We developed a physics-based model of particle light scattering within the sensor, which we used to predict counting and sizing efficiency for 0.30 to 10 μm particles. We found that the PMS5003 counts single particle scattering events, acting like an imperfect optical particle counter, rather than a nephelometer. As particle flow is not focused into the core of the laser beam, >99% of particles that flow through the PMS5003 miss the laser, and those that intercept the laser usually miss the focal point and are subsequently undersized, resulting in erroneous size distribution data. Our model predictions of PMS5003 response to varying particle diameters, aerosol compositions, and relative humidity were consistent with laboratory data. Computational fluid dynamics simulations of the PurpleAir monitor housing showed that for wind-speeds less than 3 m s, fine and coarse particles were representatively aspired to the PMS5003 inlet. Our measurements and models explain why the PurpleAir overstates regulatory PM in some locations but not others; why the PurpleAir PM is unresponsive to windblown dust; and why it reports a similar particle size distribution for coarse particles as it does for smoke and ambient background aerosol.
Evaluation of a non-dispersive infrared spectrometer for quantifying organic and elemental carbon in diesel particulate matter.
Parks DA, Zhao Y, Griffiths PR … +1 more , Miller AL
Aerosol Sci Technol · 2024 Mar · PMID 38799182 · Full text
Diesel particulate matter (DPM) is a common and well-known health hazard in the mining environment. The regulatory method for monitoring both the organic and elemental carbon (OC, EC) portions of DPM is a laboratory-base...
Diesel particulate matter (DPM) is a common and well-known health hazard in the mining environment. The regulatory method for monitoring both the organic and elemental carbon (OC, EC) portions of DPM is a laboratory-based thermal-optical method with a typical turnaround time of one week. In order to evaluate exposure levels and take corrective action prior to overexposure, a portable real-time device capable of quantifying both OC and EC is needed. To that end, researchers from the National Institute for Occupational Safety and Health (NIOSH) designed and tested the feasibility of a device based on bandpass optical filters that target key infrared wavelengths associated with DPM and its spectroscopic baseline. The resulting device, referred to here as a non-dispersive infrared (NDIR) spectrometer could serve as the basis of a cost-effective, field-portable alternative to the laboratory thermal-optical method. The limits of quantification (LOD) indicate that the NDIR spectrometer can quantify EC, OC, and TC provided they are present at 20, 37, and 46 μg/m or more, respectively. In the event that the NDIR spectrometer is integrated with a sampler and filter tape the LOD is estimated to be reduced to 13, 7, and 10 μg/m for EC, OC, and TC, respectively. These LOD estimates assume a face velocity of 59 cm/s and a sampling time of 30 min.
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