Micron Aerosol Research Articles

Individual Micron-Sized Aerosol Qualitative Analysis-Combined Raman Spectroscopy and Laser-Induced Breakdown Spectroscopy by Optical Trapping in Air.

The attribution of single particle sources of atmospheric aerosols is an essential problem in the study of air pollution. However, it is still difficult to qualitatively analyze the source of a single aerosol particle using noncontact in situ techniques. Hence, we proposed using optical trapping to combine gated Raman spectroscopy with laser-induced breakdown spectroscopy (LIBS) in a single levitated micron aerosol. The findings of the spectroscopic imaging indicated that the particle plasma formed by a single particle ablation with a pulsed laser within 7 ns deviates from the trapped particle location. The LIBS acquisition field of view was expanded using the 19-bundle fiber, which also reduces the fluctuation of a single particle signal. In addition, gated Raman was utilized to suppress the fluorescence and increase the Raman signal-to-noise ratio. Based on this, Raman can measure hard-to-ionize substances with LIBS, such as sulfates. The LIBS radical can overcome the restriction that Raman cannot detect ionic chemicals like fluoride and chloride in halogens. To test the capability of directly identifying distinctive feature compounds utilizing spectra, we detected anions using Raman spectroscopy and cations using LIBS. Four typical mineral aerosols are subjected to precise qualitative evaluations (marble, gypsum, baking soda, and activated carbon adsorbed potassium bicarbonate). To further validate the application potential for substances with indistinctive feature discrimination, we employed machine learning algorithms to conduct a qualitative analysis of the coal aerosol from ten different origin regions. Three data fusion methodologies (early fusion, intermediate fusion, and late fusion) for Raman and LIBS are implemented, respectively. The accuracy of the late fusion model prediction using StackingClassifier is higher than that of the LIBS data (66.7%) and Raman data (86.1%) models, with an average accuracy of 90.6%. This research has the potential to provide online single aerosol analysis as well as technical assistance for aerosol monitoring and early warning.

Characterization of the indoor far-field aerosol transmission in a model commercial office building

As businesses gradually reopen and employees return to work, the potential spread of SARS-CoV-2 and its variants through airborne transmission via the heating, ventilation, and air-conditioning (HVAC) systems of commercial building raises concerns. Since the general practice in commercial buildings is to use low-efficiency air filters and given that indoor air is generally recycled, the degree to which cross-zone aerosol transmission occurs is of interest. To quantify the cross-zone aerosol transmission, experiments were conducted using a synthetic test aerosol in the five zones on the first floor of a model commercial office building at the Oak Ridge National Laboratory. Because the synthetic aerosol was tagged with fluorescent salt, the aerosol generated from the source zone can be distinguished from the background aerosols due to its unique fluorescent signal. Data from cross-zone campaigns showed that submicron-aerosol transmission was higher than the micron aerosols. In campaigns with doors closed, the submicron aerosol transmission was less than 16% and less than 11% for micron aerosol transmission. Opening the interior doors that connecting different zones can significantly enhance the aerosol transmission for zones at the close proximity to the source, but has less impact on those farther away.

Physical and chemical properties of atmospheric aerosols in Moscow and its suburb for climate assessments

The paper presents results of experimental study of the physicochemical properties of surface aerosols in the Moscow region in the summer of 2019. Microphysical parameters, mass concentration and elemental composition of submicron and micron aerosol particles are considered, and their morphological structure is described. The features of variability of aerosol characteristics under atypical weather conditions prevailing in June-July 2019 are shown. The spatial distribution of the elemental composition of aerosols is established, a significant degree of their enrichment with heavy metals and metalloids is revealed. Geochemical analysis of aerosols and soils in Moscow was performed, and the coefficients of local aerosol concentration were calculated. The obtained experimental data will be useful for the refinement and verification of climate models.

Sub micron aerosol variability and its ageing process at a high altitude site in India: Impact of meteorological conditions

The effect of relative humidity and temperature on the submicron aerosol variability and its ageing process was studied over a high altitude site, Mahabaleshwar in south-west India. The mass composition of non-refractory particulate matter of 1 μm (NR-PM1) size was obtained using Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM) along with the measurements on a few trace gases during winter (December 2017–February 2018) and summer season (20th March - 5th May 2018). Sulfate exhibited strong dependence on the relative humidity (RH) as its mass fraction increased with the increase in RH. The Sulfate oxidation ratio (SOR) calculated during summer season also showed an increasing trend with RH indicating the influence of aqueous phase oxidation on sulfate fraction. On the other hand, OOA showed remarkable enhancement in its mass fraction with the increase in temperature along with the corresponding increase in f44 and tropospheric ozone. OOA, ozone and f44 ratio increased 14–34%, 8–26% and 25–43% respectively with the increase in temperature from 18 to 30 °C. This is indicative of the dominance of photochemical ageing processes during high temperature conditions. The extent of photochemical ageing was found to be higher during summer season (mean temperature ∼25.4 ± 2.6 °C) as compared to winter season (mean temperature ∼20.5 ± 2.6 °C). The nitrate diurnal was majorly governed by gas to particle partitioning process during winter season, whereas the summertime nitrate diurnal was influenced primarily by its formation rate. The non parametric wind regression analysis revealed that the mass concentration during winter was majorly contributed by distant sources from north east direction while during summer the local sources were more dominant.

The Use of Nonlinear Acoustics as an Energy-Efficient Technique for Aerosol Removal

This article is a feasibility study on using nonlinear acoustic effects, acoustic streaming and acoustic radiation pressure, for aerosol removal in an air duct. Unlike previous research, which used acoustics solely to cause aerosol agglomeration prior to aerosol removal in traditional duct collection systems, this article considers the acoustic streaming effect, which is significant but was previously neglected. Monodispersed polystyrene spheres with diameters ranging from 0.3 to 6 μm were tested. The proposed system removed 12–20% of the submicron aerosols and 25–32% of the micron aerosols when the airflow rate was approximately 90 L/min. Acoustic streaming introduces stagnation points on the surface of the air duct and removes the aerosols by deposition. Acoustic radiation pressure causes aerosols to form agglomerates. This enhances inertial impaction and/or gravitational sedimentation, which further enhances the removal efficiency of micron aerosols. The particle-removal efficiency is proportional to the duration that the aerosols are exposed to the acoustic field. The pressure drop due to the nonlinear acoustic effects is negligible; thus, power consumption is minimal. This system has the potential to be developed into an energy-efficient technique for aerosol removal.Copyright 2014 American Association for Aerosol Research

Physical and mathematical model of the coagulation of micron and submicron aerosols with regard for evaporation and sedimentation at ultrasonic effect

A physical and mathematical model is proposed, which is based on the Smolukhovsky’s equation describing the dynamics of the variation of the distribution function of aerosol particles over their sizes with regard for ultrasonic action, evaporation (for liquid-drop aerosols), and sedimentation. The expressions are obtained for the coagulation kinetics depending on the main parameters of action, the properties of aerosol and medium: the concentration and dispersion composition of the original aerosol, viscosity and temperature of the medium, physical-chemical parameters of particles material. Computational results obtained by using the proposed model correspond to experimental data.

Weekly periodicities of aerosol properties observed at an urban location in India

Multi-year (~ 7 years) observations of aerosol optical and microphysical properties were conducted at a tropical urban location in Bangalore, India. As a consequence of rapid urbanization, Bangalore presents high local atmospheric emissions, which makes it an interesting site to study the effect of anthropogenic activities on aerosol properties. It has been found that both column (aerosol optical depth, AOD) and ground-level measurements (black carbon (BC) and composite aerosol mass) exhibit a weekly cycle with low aerosol concentrations on weekends. In comparison to the weekdays, the weekend reductions of aerosol optical depth, black carbon and composite aerosol mass concentrations were ~ 15%, 25% and 24%, respectively. The magnitude of weekend reduction of black carbon is as much as ~ 1 μg m − 3 . The similarity in the weekly cycle between the column and surface measurements suggests that the aerosol column loading at this location is governed by local anthropogenic emissions. The strongest weekly cycle in composite aerosol mass concentration was observed in the super micron mass range (> 1 μm). The weekly cycle of composite aerosol mass in the sub micron mass range (< 1 μm) was weak in comparison to the super micron aerosol mass.

Temporal variability of the chemical composition of surface aerosol in the Moscow region in 1999–2005 from the results of infrared spectroscopy of aerosol samples

The temporal variability of the chemical composition of surface aerosol with particle diameters of 0.7–2 μm is analyzed. This analysis is based on the results of measurements of infrared transmission spectra of aerosol samples collected with the use of a cascade impactor at the Zvenigorod Scientific Station of the Institute of Atmospheric Physics (IAP) in 1999–2005. Seasonal features of the aerosol chemical composition and its dependence on the particle size are revealed. The interdiurnal variability of the aerosol composition depends on the season, and it manifests itself more strongly in winter and spring. Air-mass changes lead to changes in the relation of sulfates and nitrates in the micron fraction of aerosol. The enrichment of samples in nitrates is especially characteristic of the winter and spring seasons. Compounds containing the NO2 group are often met in the samples of aerosol with particle sizes of 0.7–1.3 μm during the cold time of the year. The estimates of the optical thickness of micron aerosol in the sulfate absorption band are obtained, and optical-thickness variations of some scales are detected. The quantitative characteristics of statistical relations between different chemical components of aerosol inside individual fractions and between chemical components of the micron and submicron fractions are obtained and analyzed.

Retrieval of Columnar Aerosol Size Distributions from Spectral Attenuation Measurements over Central Himalayas

Extensive measurements of spectral aerosol optical depths (AODs) were made at Manora Peak, Nainital (29.4o N, 79.5o E, ~1958 m above mean sea level) in the central Himalayas, using a ten channel multi-wavelength solar radiometer during January 2002 to December 2005. Using these spectral AOD values, the columnar size distribution [CSD; nc(r)] function of aerosols have been derived. The CSD, retrieved from spectral AODs are, in general, bimodal (combination of power law and unimodal log normal distribution) with a prominent secondary (or coarse) mode occurring at a fairly large value of radius (r > 0.5 µm), while the primary (or fine) mode either does not appear explicitly or perhaps occurs below the radius  0.1 µm. The bimodal nature of CSDs indicates the presence of fine as well as coarse mode aerosols over the observational site. The effective radius, total aerosol number content and columnar mass loading computed from deduced CSD shows minimum values during winter (November to February) and maximum during summer (March to June) months. The share of sub micron and super micron aerosols to the total aerosol number concentration (Nt) indicates the dominance of sub micron aerosols to the Nt and it accounts for > 90% during the study period.

Retrieval of Columnar Aerosol Size Distributions from Spectral Attenuation Measurements over Central Himalayas

Extensive measurements of spectral aerosol optical depths (AODs) were made at Manora Peak, Nainital (29.4°N, 79.5°E,~1958 m above mean sea level) in the central Himalayas, using a ten channel multi-wavelength solar radiometer during January 2002 to December 2005. Using these spectral AOD values, the columnar size distribution [CSD; n(subscript c)(r)] function of aerosols have been derived. The CSD, retrieved from spectral AODs are, in general, bimodal (combination of power law and unimodal log normal distribution) with a prominent secondary (or coarse) mode occurring at a fairly large value of radius (r＞0.5 μm), while the primary (or fine) mode either does not appear explicitly or perhaps occurs below the radius ≌0.1 μm. The bimodal nature of CSDs indicates the presence of fine as well as coarse mode aerosols over the observational site. The effective radius, total aerosol number content and columnar mass loading computed from deduced CSD shows minimum values during winter (November to February) and maximum during summer (March to June) months. The share of sub micron and super micron aerosols to the total aerosol number concentration (N(subscript t)) indicates the dominance of sub micron aerosols to the N(subscript t) and it accounts for ＞90% during the study period.

Ambient aerosol concentrations of sugars and sugar-alcohols at four different sites in Norway

Abstract. Sugars and sugar-alcohols are demonstrated to be important constituents of the ambient aerosol water-soluble organic carbon fraction, and to be tracers for primary biological aerosol particles (PBAP). In the present study, levels of four sugars (fructose, glucose, sucrose, trehalose) and three sugar-alcohols (arabitol, inositol, mannitol) in ambient aerosols have been quantified using a novel HPLC/HRMS-TOF (High Performance Liquid Chromatography in combination with High Resolution Mass Spectrometry – Time of Flight) method to assess the contribution of PBAP to PM&gt;sub&gt;10 and PM2.5. Samples were collected at four sites in Norway at different times of the year in order to reflect the various contributing sources and the spatial and seasonal variation of the selected compounds. Sugars and sugar-alcohols were present at all sites investigated, underlining the ubiquity of these highly polar organic compounds. The highest concentrations were reported for sucrose, reaching a maximum concentration of 320 ng m−3 in PM10 and 55 ng m−3 in PM2.5. The mean concentration of sucrose was up to 10 times higher than fructose, glucose and the dimeric sugar trehalose. The mean concentrations of the sugar-alcohols were typically lower, or equal, to that of the monomeric sugars and trehalose. Peak concentrations of arabitol and mannitol did not exceed 30 ng m−3 in PM10, and for PM2.5 all concentrations were below 6 ng m−3. Sugars and sugar-alcohols were associated primarily with coarse aerosols except during wintertime at the suburban site in Elverum, where a shift towards sub micron aerosols was observed. It is proposed that this shift was due to the intensive use of wood burning for residential heating at this site during winter, confirmed by high concurrent concentrations of levoglucosan. Elevated concentrations of sugars in PM2.5 were observed during spring and early summer at the rural background site Birkenes. It is hypothesized that this was due to ruptured pollen.

Experimental study of aerosol concentration in flow-through, low-frequency resonators

An experimental method to study the concentration of micron-sized aerosols in a low-frequency sound field was developed. The physical mechanism for acoustic aerosol concentration in a low-frequency sound field is the asymmetric Stokes drag which has been predicted to exceed the effects of radiation pressure for typical aerosol sizes [Meegan and Ilinskii, J. Acoust. Soc. Am. 114, 2387 (2003)]. Related experiments were conducted in which 5 micron aerosol was drawn through a small duct that was driven in a transverse resonant mode with peak sound pressure levels of greater than 150 dB re 20 microPascals and frequencies in the range 1 to 10 kHz. The aerosol stream was illuminated by a laser sheet through the transparent walls of the duct in order to visualize (by video) the effects of the sound field. The experiments confirm the basic feature of the asymmetric Stokes drag model—specifically, the aerosol is observed to concen- trate along acoustic velocity nodes. Ongoing experiments to quantify the level of concentration will be described. [Work supported by RDECOM.]

Vertical profiles of O3, aerosols, CO and NMHCs in the Northeast Pacific during the TRACE‐P and ACE‐ASIA experiments

Airborne observations of NMHCs, O3, CO, and aerosol scatter were made near the coast of Washington State from 29 March to 6 May 2001 as part of the Photochemical Ozone Budget of the Eastern North Pacific‐II (PHOBEA‐II) experiment. These observations overlapped the time period of the TRACE‐P (24 February to 10 April 2001) and ACE‐ASIA (27 March to 30 April 2001) experiments operating in the Western Pacific. Measurements were made during 12 flights at 48.31 ± 0.03°N latitude, 124.63 ± 0.08°W longitude at altitudes from 0 to 6 km. On several flights, significant enhancements in all species were observed and are attributed to transport from the Eurasian continent, including a long‐range transport event observed on 14 April 2001. This event contained substantial CO, NMHC, and aerosol loadings and was identified by the Total Ozone Mapping Spectrometer (TOMS) aboard the Earth Probe Satellite and airborne and surface measurements throughout North America. This airmass was unique in that it contained the highest levels of aerosol scatter, CO, and various NMHCs observed in 2001, was the only flight with a low Ångstrom coefficient (0.7) indicating dominance of super micron aerosols, and had a negative relationship between ozone and aerosol scatter (r = −0.30). Within this mineral dust and pollution layer, aerosol scatter, propane, and CO were enhanced by 1054%, 85%, and 36%, respectively, over the observed spring 2001 median values between 3.5 and 6 km. A comparison of our previous aircraft campaign in 1999 with 2001 observations shows that ozone, aerosol scatter, and most NMHCs were significantly lower in the spring of 2001. The exact cause is still under investigation, but the combination of elevated ozone, aerosol scatter, and NMHCs suggests a combustion source that was enhanced and/or transported more efficiently during the spring of 1999.

A sea spray generation function for fetch-limited conditions

Abstract. This paper presents a sea spray generation function for aerosols produced by bubbles bursting that accounts for the effects of fetch. This is achieved by introducing a fetch-dependent model for the whitecap fraction, which is valid for fetch-limited conditions, i.e. steady-state conditions of the wave field in the whitecap droplet flux derived by Monahan et al. (1986). The aerosol generation fluxes calculated by this method show an enhancement of the aerosol production with increasing fetch. However, the predicted generation fluxes are lower than those calculated by using the classical model for the whitecap fraction proposed by Monahan and O’Muircheartaigh (1980). The results are then compared to aerosol size distributions measured in a Mediterranean coastal site at various fetch lengths. The data confirm the role of fetch, through its influence on marine aerosol generation and subsequent particle dispersion. The aerosol size distributions are divided into "fine" and "coarse" fractions. Submicrometer particles decrease in concentration at larger fetch, while the concentrations of super micron aerosols increase with increasing fetch.Key words. Atmospheric composition and structure (aerosols and particles) Meteorology and atmospheric dynamics (waves and ties) Oceanography: physical (air-sea interactions)

Effect of Aerosol Size on the Clearance of DTPA from Lungs of Anesthetized Sheep

Aerosolized 99mTc–diethylenetriamine pentaacetate (DTPA) clears uniformly from the air spaces in control sheep. However, in response to increased lung volume due to a positive end expired pressure (PEEP) of 10 cmH20, a portion of the DTPA clears very rapidly (fast compartment) while the remainder clears at a normal rate. We tested the hypothesis that the fraction of DTPA that cleared rapidly from the lungs was proportional to the fraction that deposited in the alveoli. We performed a compartment analysis of the clearance of DTPA delivered to anesthetized sheep in 4 different size aerosols. When the DTPA was delivered in a 1.0 micron aerosol, 77 ± 7% of the DTPA cleared rapidly. This fraction decreased with increasing aerosol size with only 36 ± 14% of the DTPA clearing rapidly for the 6.8 micron aerosol. A postmortem analysis of the site of deposition of the aerosols confirmed that the 1.0 micron aerosol deposited primarily in the alveoli and small airways (<1 mm diameter) and the 6.8 micron aerosol deposited primarily in 7–8 mm airways. Therefore, the fast compartment in the clearance of DTPA from lungs ventilated with a PEEP of 10 cmH2O represents the fraction of the DTPA that deposited in the alveoli and small airways. This compartment analysis of the clearance rate may be useful as a noninvasive index of peripheral deposition of aerosols.

Development of an aerosol dispersion test to detect early changes in lung function.

The dispersion of a 0.5 micron aerosol bolus during tidal breathing differs significantly (p less than 0.0001) between a group of smokers (with approximately 20 pack-years average exposure) and a comparable group of nonsmokers. Their mean differences in standard respiratory function indexes from spirometry [forced vital capacity (FVC), forced expiratory volume in one second (FEV1), mean forced expiratory flow during the middle half of the FVC (FEF25-75)] were smaller and not statistically significant. The test is simple to perform and may be done as quickly as spirometry but without using a forced exhalation. Comparison of the coefficients of variation for the dispersion test and FEV1 indicate that the aerosol dispersion test may be useful in epidemiologic investigations either by reducing the required population size or increasing the level of confidence.

The breathing of half micron aerosols—III dispersion of particles in the respiratory tract

Experiments on the inhalation of 0·5 μm dia. particles are described. For a single inhalation of aerosol the effects of separately varying tidal volume and expiratory reserve volume were studied. The results are consistent with the idea that mechanical mixing within the tidal air and between the tidal and reserve air takes place only in the anatomical dead space of the lungs. Experiments with constant reserve volume on the inhalation of a bolus or slug of aerosol, followed by clean air to complete the tidal inhalation, showed that the depth of penetration of the aerosol into the reserve air was not much less than when aerosol was inhaled for the entire tidal inhalation. This indicates that the first part of tidal air, which penetrates most deeply, is not much affected by the volume subsequently inhaled, the reason being that it is in the alveolated airways where there is no mechanical mixing of air. This supports the ‘first in, last out’ theory of breathing, subject to some spreading in volume. A compartment theory of the dispersion of particles in the lungs, based on tidal, reserve and residual volumes, enables six transfer coefficients of aerosol particles to be evaluated from wash-in and wash-out experiments. With these coefficients it is possible to predict the behaviour of aerosols during various breathing manoeuvres. The theory is independent of assumptions about the mechanisms of particle exchange. Evaluation of the transfer coefficients would identify differences between subjects and could be of clinical interest.

Distribution of aerosol particles in exhaled air.

ArticleDistribution of aerosol particles in exhaled air.D C MuirD C MuirPublished Online:01 Aug 1967https://doi.org/10.1152/jappl.1967.23.2.210MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByRecent Advances in Understanding Gas and Aerosol Transport in the Lungs: Application to Predictions of Regional DepositionBehaviour of Airborne Particles in the Respiratory Tract30 May 2008Calculation of Equivalent Aerosol Particle Mobility in Different Mixtures of Gases Used to Study Convective Transport in AirwaysJournal of Aerosol Medicine, Vol. 3, No. 4Effect of Cystic Fibrosis on Inhaled Aerosol BolusesAmerican Review of Respiratory Disease, Vol. 140, No. 5MODELLING AN AEROSOL DISPERSION TEST FOR DETECTING EARLY AIRWAY CHANGESPOSTER/DISCUSSION SESSION 7 : DIAGNOSTIC, PROPHYLACTIC AND THERAPEUTIC APPLICATIONS OF AEROSOLSJournal of Aerosol Medicine, Vol. 1, No. 3The Use of Light Scattering Photometry in Aerosol MedicineJournal of Aerosol Medicine, Vol. 1, No. 2Ventilation: Total, Alveolar, and Dead Space1 January 2011Mass distribution of chemical species in a polydisperse aerosol: Measurement of sodium chloride in particles by mass spectrometryJournal of Colloid and Interface Science, Vol. 112, No. 2Real-time measurement of sodium chloride in individual aerosol particles by mass spectrometry1 May 2002 | Analytical Chemistry, Vol. 57, No. 9Quantitative measurement of total aerosol lung deposition: Comparison of three different techniquesJournal of Aerosol Science, Vol. 16, No. 5Aerosol contributions to the investigation of lung structure and ventilatory functionBronchial Bifurcations and Respiratory Mass TransportScience, Vol. 208, No. 4439Lung tests based on aerosol depositionJournal of Aerosol Science, Vol. 10, No. 2Dispersion of inhaled particles in the human lungsPowder Technology, Vol. 18, No. 1Mixing in flowing gasRespiration Physiology, Vol. 30, No. 1-2Transport of O2 along a model pathway through the respiratory region of the lungBulletin of Mathematical Biology, Vol. 36, No. 3Pulmonary gas transport characterization by a dynamic modelRespiration Physiology, Vol. 12, No. 3The breathing of half micron aerosols—III dispersion of particles in the respiratory tractJournal of Aerosol Science, Vol. 2, No. 4 More from this issue > Volume 23Issue 2August 1967Pages 210-4 https://doi.org/10.1152/jappl.1967.23.2.210PubMed6031190History Published online 1 August 1967 Published in print 1 August 1967 Metrics

Human respiratory and ocular irritation studies utilizing o-chlorobenzylidene malononitrile aerosols.

Abstract Studies have been made with humans to determine the influence of one and sixty micron aerosols of o-chlorobenzylidene malononitrile on respiratory and ocular irritating effects. Small particles rapidly produce respiratory and ocular irritation. Only 3 of 17 individuals could tolerate small particles for as long as 60 seconds. Large particles predominately produce ocular irritation. Of 18 subjects exposed, 15 were able to tolerate the cloud for at least 60 seconds. Large particles increase recovery time from ocular irritation.