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The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles.

Cooney DJ, Hickey AJ - Int J Nanomedicine (2008)

Bottom Line: Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm.Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process.Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA. cooneyinsf@gmail.com

ABSTRACT
The influence of diesel exhaust particles (DEP) on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process.

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Related in: MedlinePlus

Scanning electron micrographs of diesel exhaust particles in bulk at (a) 1000X and (b) 10000X.
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f6-ijn-3-435: Scanning electron micrographs of diesel exhaust particles in bulk at (a) 1000X and (b) 10000X.

Mentions: SEM images of DEP can be seen in Figure 6. The particles were highly aggregated. The primary particles are not distinct, but give the powders a fluffy appearance. SEM images of DEP deposited from a 1.0 mg/g suspension on stages 3–6 of the NVCI (60 L/min) are shown in Figure 7 (particles from the other concentrations looked very similar and are not shown). The particles appear to be roughly spherical aggregates with diameters dependant on the stage on which they deposited. As with the bulk powder, the primary particles in the aggregates cannot be distinguished, but give a fluffy appearance. Images of DEP deposited from a 1.0 mg/g suspension on stage 2 of the ELPI are shown in Figure 8 (particles deposited on stages 1 and 3, and from the other concentrations looked very similar and are not shown). The particles on this stage of the ELPI (32 nm cutoff) are generally smaller and with a wider range of sizes and shapes, than those seen in the lowest stage of the NVCI (200 nm cutoff for stage 6). The physical diameters of the DEP deposited on stage 2 of the ELPI varies from <50 nm to ~1 μm, which is much larger than the aerodynamic diameter range corresponding to that stage (32–51 nm). This discrepancy may be due to the aggregation of multiple aerosol particles after deposition, but it is impossible to make that determination. It is also possible that a low density and nonspherical shape gave the particles an aerodynamic diameter much smaller than their physical diameter, although it is unlikely that a particle with a physical dimension of 1 μm had an aerodynamic diameter 20-fold less. Poor impactor efficiency and/or reintrainment of particles from the upper stages may have also contributed to the deposition of large particles on this stage.


The generation of diesel exhaust particle aerosols from a bulk source in an aerodynamic size range similar to atmospheric particles.

Cooney DJ, Hickey AJ - Int J Nanomedicine (2008)

Scanning electron micrographs of diesel exhaust particles in bulk at (a) 1000X and (b) 10000X.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2636590&req=5

f6-ijn-3-435: Scanning electron micrographs of diesel exhaust particles in bulk at (a) 1000X and (b) 10000X.
Mentions: SEM images of DEP can be seen in Figure 6. The particles were highly aggregated. The primary particles are not distinct, but give the powders a fluffy appearance. SEM images of DEP deposited from a 1.0 mg/g suspension on stages 3–6 of the NVCI (60 L/min) are shown in Figure 7 (particles from the other concentrations looked very similar and are not shown). The particles appear to be roughly spherical aggregates with diameters dependant on the stage on which they deposited. As with the bulk powder, the primary particles in the aggregates cannot be distinguished, but give a fluffy appearance. Images of DEP deposited from a 1.0 mg/g suspension on stage 2 of the ELPI are shown in Figure 8 (particles deposited on stages 1 and 3, and from the other concentrations looked very similar and are not shown). The particles on this stage of the ELPI (32 nm cutoff) are generally smaller and with a wider range of sizes and shapes, than those seen in the lowest stage of the NVCI (200 nm cutoff for stage 6). The physical diameters of the DEP deposited on stage 2 of the ELPI varies from <50 nm to ~1 μm, which is much larger than the aerodynamic diameter range corresponding to that stage (32–51 nm). This discrepancy may be due to the aggregation of multiple aerosol particles after deposition, but it is impossible to make that determination. It is also possible that a low density and nonspherical shape gave the particles an aerodynamic diameter much smaller than their physical diameter, although it is unlikely that a particle with a physical dimension of 1 μm had an aerodynamic diameter 20-fold less. Poor impactor efficiency and/or reintrainment of particles from the upper stages may have also contributed to the deposition of large particles on this stage.

Bottom Line: Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm.Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process.Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA. cooneyinsf@gmail.com

ABSTRACT
The influence of diesel exhaust particles (DEP) on the lungs and heart is currently a topic of great interest in inhalation toxicology. Epidemiological data and animal studies have implicated airborne particulate matter and DEP in increased morbidity and mortality due to a number of cardiopulmonary diseases including asthma, chronic obstructive pulmonary disorder, and lung cancer. The pathogeneses of these diseases are being studied using animal models and cell culture techniques. Real-time exposures to freshly combusted diesel fuel are complex and require significant infrastructure including engine operations, dilution air, and monitoring and control of gases. A method of generating DEP aerosols from a bulk source in an aerodynamic size range similar to atmospheric DEP would be a desirable and useful alternative. Metered dose inhaler technology was adopted to generate aerosols from suspensions of DEP in the propellant hydrofluoroalkane 134a. Inertial impaction data indicated that the particle size distributions of the generated aerosols were trimodal, with count median aerodynamic diameters less than 100 nm. Scanning electron microscopy of deposited particles showed tightly aggregated particles, as would be expected from an evaporative process. Chemical analysis indicated that there were no major changes in the mass proportion of 2 specific aromatic hydrocarbons (benzo[a]pyrene and benzo[k]fluoranthene) in the particles resulting from the aerosolization process.

Show MeSH
Related in: MedlinePlus