OBJECTIVESDeliberate or accidental release of chemical treat agents in the aerosol form can cause an inhalation hazard. Since the relationship between aerosol properties and health hazards is poorly ...understood, research into the toxicological consequences of exposure to aerosols is needed. The aim of the present study was to improve the characterization of particles for inhalation studies.METHODSSeveral aerosol measurement technologies were compared for their potential to physically and chemically characterize particles in the inhalation size range in real-time. For that purpose, we compared the performance of an aerodynamic particle sizer (APS), a scanning mobility particle sizer (SMPS) and an electrical low-pressure impactor (ELPI) in an experimental set-up in which particles were generated by a Collison nebulizer and subsequently delivered into a nose-only inhalation exposure system.RESULTSWe found that more than 95% of the number of particles, equating to more than 83% of the mass generated by the 6-jet Collison nebulizer, were below 0.5 µm. To characterize the entire size range, the APS as single detector has only limited value, therefore the addition of supplementary instrumentation such as the SMPS or the ELPI is required. After real-time measurements in the size range of 30 nm to 10 µm, ex-situ chromatographic chemical analysis is essential for quantification of the delivered mass concentration.CONCLUSIONSIn summary, the present work demonstrates the utility of the ELPI technology, in combination with off-line analysis, for characterizing aerosols with various size, shape, charge, and composition. This makes the aerosol generation and analysis suite described a promising tool for quantitative inhalation exposure studies.
A mass balance method is applied to assess main source contributions to PM2.5 and PM10 levels in Karachi. Carbonaceous species (elemental carbon, organic carbon, carbonate carbon), soluble ions ...(Ca++, Mg++, Na+, K+, NH4+, Cl−, NO3−, SO4−), saccharides (levoglucosan, galactosan, mannosan, sucrose, fructose, glucose, arabitol and mannitol) were determined in atmospheric fine (PM2.5) and coarse (PM10) aerosol samples collected under pre-monsoon conditions (March–April 2009) at an urban site in Karachi (Pakistan). The concentrations of PM2.5 and PM10 were found to be 75 μg/m3 and 437 μg/m3 respectively. The large difference between PM10 and PM2.5 originated predominantly from mineral dust. “Calcareous dust” and „siliceous dust” were the over all dominating material in PM, with 46% contribution to PM2.5 and 78% to PM10–2.5. Combustion particles and secondary organics (EC + OM) comprised 23% of PM2.5 and 6% of PM10–2.5. EC, as well as OC ambient levels were higher (59% and 56%) in PM10–2.5 than in PM2.5. Biomass burning contributed about 3% to PM2.5, and had a share of about 13% of “EC + OM” in PM2.5. The impact of bioaerosol (fungal spores) was minor and had a share of 1 and 2% of the OC in the PM2.5 and PM10–2.5 size fractions. In case of secondary inorganic aerosols, ammonium sulphate (NH4)2SO4 contributes 4.4% to PM2.5 and no detectable quantity were found in fraction PM10–2.5. The sea salt contribution is about 2% both to PM2.5 and PM10–2.5.
•This study focuses on the impact of biomass burning in an urban environment.•Carbonaceous species like EC, OC, and anhydrosugars along with water soluble ions has been measured in the mega city of Karachi.•Levoglucosan has been used as tracer for biomass burning.
•Light-scattering angular spectrum is proposed for high-resolution particle sizing.•A compacted and lens-free optical system is designed for LSAS sampling.•The particle size distribution is inversed ...with high accuracy (DKL < 0.05).•The sensor is low-cost and portable for in-situ aerosol contamination measurement.
In the study of aerosols, great concern has been focused on the particle size distribution (PSD) as a crucial factor of the physical and chemical properties of the aerosols. There are strong and growing demands for on-line and in-situ aerosol analysis technologies, but existing portable aerosol sensors can hardly provide high-resolution and accurate PSD measurement with limited volume and cost. To address this challenge, we introduce the concept of a new optical aerosol sensing method using light-scattering angular spectrum (LSAS), which describes the angular dependence of the scattering light intensity. The key novelty is a compacted LSAS sampling module for collecting the scattering light up to the observing angles. According to the wide-range LSAS sampled by our sensor, high-resolution PSD is predicted by non-negative regularization inversion algorithm. To validate the performance of our sensor, monodisperse di-ethyl-hexyl-sebacate aerosols (DEHS) samples of different sizes and smokes of smoldering cotton rope were tested. The maximum relative error (RE) of LSAS was smaller than 12.02%, while the Kullback-Leibler Divergence (DKL) between inversed and reference PSDs were smaller than 0.05. Without using any particulate pre-separation module and optical lens, we build a novel low-cost and miniaturized sensor only composed of a mirror, a linear charge coupled device (CCD) and a semiconductor laser, which has significant potential for high-resolution aerosol sizing in routine field measurements outside a laboratory.
Analysis of water soluble ions in PM10 in Pakistan is limited and therefore requires in-depth investigation. In this study composition and sources of ionic profile in PM10 were determined from an ...urban site of an Asian megacity (Faisalabad) in 2015–2016. The PM10 size fraction sampled on quartz filters was analyzed by ion chromatography for selected inorganic and organic ions. The daily mean PM10 mass concentration was found to be 744 ± 392 μgm−3, exceeding the limits proposed by Pak-EPA (150 μgm−3), US-EPA (150 μgm−3) and WHO (50 μgm−3). The ambient PM10 concentration was found to be highest in winter 2015-16 and autumn 2016, while the lowest in the monsoon 2016. The average total ion concentration was found to be 120 ± 51 μgm−3, which made about 16% of the total PM10 mass. CO32− was the most dominant specie followed by NH4+, Ca2+, K+, NO3−, SO42−, C2O42−, CH3COO−, Na+, Cl− and Mg2+. The ratio analysis of selected ions indicated dominant contribution of biomass burning during autumn and winter and higher impact of fossil fuel burning during spring and summer seasons. Positive Matrix Factorization identified traffic induced soil erosion, biomass burning, fugitive dust from construction activities, secondary aerosol formation processes and fossil fuel emissions from traffic and industry as major sources of particulates.
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•Ions & their sources in PM10 were evaluated from a site in the Indo-Gangetic Plain.•The PM10 values were exceeding the limits fixed by Pak-EPA, US-EPA and WHO.•The total ionic concentration constituted about 16% of the total PM10 mass.•CO32− > NH4+ > Ca2+ > K+ > NO3− > SO42− > C2O42− > CH3CO2− > Na+ > Cl− > Mg2.•Source apportionment was carried out by using PMF model.
This paper uses a mathematical model of fluorescent biological particles composed of bacteria and/or proteins (mostly as in Hill et al., 2013 23) to investigate the size-dependence of the total ...fluorescence emitted in all directions. The model applies to particles which have negligible reabsorption of fluorescence within the particle. The specific particles modeled here are composed of ovalbumin and of a generic Bacillus. The particles need not be spherical, and in some cases need not be homogeneous. However, the results calculated in this paper are for spherical homogeneous particles. Light absorbing and fluorescing molecules included in the model are amino acids, nucleic acids, and several coenzymes. Here the excitation wavelength is 266 nm. The emission range, 300 to 370 nm, encompasses the fluorescence of tryptophan. The fluorescence cross section (CF) is calculated and compared with one set of published measured values. We investigate power law (Ady) approximations to CF, where d is diameter, and A and y are parameters adjusted to fit the data, and examine how y varies with d and composition, including the fraction as water. The particle's fluorescence efficiency (QF=CF/geometric-cross-section) can be written for homogeneous particles as QabsRF, where Qabs is the absorption efficiency, and RF, the fraction of the absorbed light emitted as fluorescence, is independent of size and shape. When QF is plotted vs. mid or mi(mr-1)d, where m=mr+imi is the complex refractive index, the plots for different fractions of water in the particle tend to overlap.
We present a novel method referred to as Particle Beam Deflection Imaging (PBDI) for the simultaneous characterization of the size and electric charge distribution of submicrometer (currently ...∼200–800 nm) aerosol particles in real-time (currently ≤30 s). It combines aerodynamic and electrostatic particle deflection, providing two-dimensional information on size and charge in a single two-dimensional light scattering image. The image allows one to extract information on charge-averaged and charged-resolved particle size distributions, and on size-dependent bipolar charge distributions. The current prototype has a size resolution of <50 nm and can resolve individual charge states. Compared to Scanning Mobility Particles Sizers (SMPS), the PBDI offers the advantage of providing simultaneous size and charge information at higher size resolution in a significantly shorter measurement time, hence allowing real-time characterization of volatile aerosol particles.
•Size and charge of submicrometer aerosol particles are characterized simultaneously.•Aerodynamic and electrostatic deflection yield 2-dimensional information.•Resolution of <50 nm and sensitivity to individual charge states is demonstrated.•The method enables real-time characterization of volatile particles.
Treprostinil palmitil (TP) is a prodrug of treprostinil that has been formulated as an inhaled powder, termed TPIP, for evaluation in patients with pulmonary arterial hypertension. In these ...characterization studies we investigated the aerosol performance of TPIP in response to changes in capsule fill, device resistance, and inspiratory flow rate to enable selection of an inhaler for clinical use. Capsules containing 8, 16 or 32 mg of TPIP (80, 160, or 320 μg TP, respectively) were evaluated using four commercially-available, breath-actuated RS01 devices (Plastiape, S. p.A., Osnago, Italy) with low, medium, high or ultra-high inspiratory resistances, creating 12 different capsule and device configurations for evaluation. Aerosol characterization was performed using the next generation impactor at compendial conditions of 23°C and 35% relative humidity and a flow rate corresponding to a 4 kPa pressure drop. The aerosol mass median aerodynamic diameter, geometric standard deviation, fine particle fraction, emitted dose and fine particle dose (FPD) were calculated from the in vitro impactor data. The TP emitted dose at 4 kPa exceeded 75% for all 12 capsule and device configurations. The FPD, an estimate of the respirable dose, varied between 61.0 and 70.6% of the loaded TP dose for all four devices with the 8 and 16 mg TPIP capsule dose. For the 32 mg TPIP capsule dose, the FPD remained above 61.0% for the high and ultra-high resistance devices but decreased to 48.5 and 52.6% for the low and medium resistance devices, respectively. Based on this initial data, the high resistance device was selected for additional characterization studies at 40 and 80 L/min corresponding to pressure drops of 1.4 and 5.4 kPa. The FPD was relatively insensitive to changes in flow rate, providing an expectation of a consistent total lung dose of TP under scenarios simulating variability in how the device is used. Based on these findings, the high resistance device was chosen for further development in human clinical trials.
The use of electronic cigarettes (E‐cigs) is rapidly increasing. The latest generation of E‐cigs is highly customizable, allowing for high heating coil temperatures. The aim of this study was to ...assess the toxic potential of a fourth‐generation E‐cig. Aerosols generated from E‐liquid with (24 mg/mL) and without nicotine, using a fourth‐generation E‐cig, were chemically analysed and compared with cigarette smoke (K3R4F). Human lung epithelial cell lines and distal lung tissue explants were exposed to E‐cig vapour extract (EVE) and cigarette smoke extract for 24 hours and assessed for viability, inflammation, oxidative stress and genotoxicity. E‐cig aerosols contained measurable levels of volatile organic compounds, aldehydes and polycyclic aromatic hydrocarbons, in general, to a much lesser extent than cigarette smoke. Higher levels of certain carbonyls, e.g. formaldehyde, were detected in the E‐cig aerosols. EVEs decreased cell viability of BEAS‐2B cells, whereas little effect was seen in A549 cells and distal lung tissue. The nicotine‐containing EVE caused a greater decrease in cell viability and significant increase in DNA damage than the nicotine‐free EVE. Increased cytotoxicity, reactive oxygen species production and genotoxicity were seen with cells and tissue exposed to cigarette smoke extract compared with EVEs. Although E‐cig aerosols were less toxic than cigarette smoke, it was not benign. Moreover, the EVE containing nicotine was more toxic than the nicotine‐free EVE. More research is needed on the short‐ and long‐term health effects of vaping and the usage of newly emerging E‐cig devices to evaluate better the potential negative effects of E‐cigs on human health.
There are few data on the toxic potential of new‐generation electronic cigarette (E‐cig) models. Aerosols generated from a fourth‐generation E‐cig contained volatile organic compounds, aldehydes and polycyclic aromatic hydrocarbons but to a lesser extent than cigarette smoke. E‐cig aerosol extracts were cytotoxic to BEAS‐2B cells, and caused increased cell death and DNA strand breaks when containing nicotine. More research is needed on the short‐ and long‐term health effects of vaping.
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