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Inhalability for aerosols at ultra-low windspeeds.

Authors
Sleeth-DK; Vincent-JH
Source
J Phys: Conf Ser, Inhaled Particles X 2009 Mar; 151(1):012062
NIOSHTIC No.
20035190
Abstract
Most previous experimental studies of aerosol inhalability were conducted in wind tunnels for windspeeds greater than 0.5 ms-1. While that body of work was used to establish a convention for the inhalable fraction, results from studies in calm air chambers (for essentially zero windspeed) are being discussed as the basis of a modified criterion. However, information is lacking for windspeeds in the intermediate range, which -- it so happens -- pertain to most actual workplaces. With this in mind, we have developed a new experimental system to assess inhalability -- and, ultimately, personal sampler performance -- for aerosols with particle aerodynamic diameter within the range from about 9 to 90 um for ultra-low windspeed environments from about 0.1 to 0.5 ms-1. This new system contains an aerosol test facility, fully described elsewhere, that combines the physical attributes and performance characteristics of moving air wind tunnels and calm air chambers, both of which have featured individually in previous research. It also contains a specially-designed breathing, heated, life-sized mannequin that allows for accurate recovery of test particulate material that has been inhaled. Procedures have been developed that employ test aerosols of well-defined particle size distribution generated mechanically from narrowly-graded powders of fused alumina. Using this new system, we have conducted an extensive set of new experiments to measure the inhalability of a human subject (as represented by the mannequin), aimed at filling the current knowledge gap for conditions that are more realistic than those embodied in most previous research. These data reveal that inhalability throughout the range of interest is significantly different based on windspeed, indicating a rise in aspiration efficiency as windspeed decreases. Breathing flowrate and mode of breathing (i.e. nose versus mouth breathing) did not show significant differences for the inhalability of aerosols. On the whole however, the data obtained here are within the range of inhalability data that exist from the large body of the previous experimental work performed at the higher windspeeds. These latest findings are an important contribution to the ongoing discussion in international standards-setting bodies about the possible adjustment of the quantitative definition of what constitutes the inhalable fraction.
Keywords
Aerosol-particles; Aerosol-sampling; Aerosols; Air-flow; Air-quality-monitoring; Air-sampling-techniques; Biological-effects; Biological-factors; Exposure-methods; Inhalation-studies; Laboratory-testing; Particle-aerodynamics; Particulate-sampling-methods; Risk-analysis; Respiratory-irritants
Contact
James H. Vincent, Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI 48109
Publication Date
20090313
Document Type
Journal Article
Email Address
jhv@umich.edu
Funding Amount
697800
Funding Type
Grant
Fiscal Year
2009
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-002987
Issue of Publication
1
ISSN
1742-6596
Priority Area
Pulmonary System Disorders
Source Name
Journal of Physics: Conference Series, Inhaled Particles X, 23-25 September 2008, Sheffield, UK
State
MI; CT
Performing Organization
Yale University, New Haven, Connecticut
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