Graduation Year

2010

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Environmental and Occupational Health

Major Professor

Yehia Y. Hammad, Sc.D.

Co-Major Professor

Thomas E. Bernard, Ph.D.

Committee Member

Steven P. Mlynarek, Ph.D.

Committee Member

Yangxin Huang, Ph.D.

Keywords

Inhalation Challenge, Generation of Aerosols, Exposure System, Aerosols, Particulates

Abstract

The purpose of this study was to characterize and evaluate the performance of a whole-body human exposure chamber for controlled test atmospheres of gases and particulates. The chamber was constructed from Plexiglass, has a volume of 75 ft 3, operated at a flowrate of 33.8 CFM, and both the makeup and exhaust air are HEPA filtered. Fly ash dust was generated using a Wright Dust Feeder. An elutriator was used to eliminate particles larger 8 μm aerodynamic diameter from the airstream. A direct reading instrument, the Rupprecht and Patashnick PM-10 TEOM, was used for determination of particle concentration. Particle size distributions were determined by a QCM cascade impactor. Data from gravimetric analysis were used to test for the evenness of dust concentrations in the chamber. CO2 is used as a representative gas and its concentration was measured using the Metrosonics aq-5000.

Total dust concentrations as measured by the TEOM, in μg/m 3, at 0.2, 0.4, 0.6 and 1.6 RPMs of the Wright Dust Feeder, were 110 + 2.8, 173 + 8.5, 398 + 20 and 550 + 17, respectively. For these RPMs, particle size distributions were associated with a MMD of 1.27 μm and a GSD of 2.35, a MMD of 1.39 and a GSD of 2.22, a MMD of 1.46 and a GSD of 2.08, a MMD of 1.15 and a GSD of 2.2, respectively. Total dust concentrations as measured by gravimetric analysis, in μg/m3

for the respirable fraction. Dust concentrations measured at different points within the chamber showed uniform distribution with a variability less than 10%. Similarly, the particle size distributions were found to be consistent across the different RPMs settings. Regarding carbon dioxide, its concentration was straightforward and the measured and theoretical maximum concentration levels were in agreement.

The performance of this whole-body human exposure chamber has been characterized and evaluated for low levels of particles and gases and now it is a valuable research tool for inhalation challenge studies.

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