ABSTRACT
BACKGROUND: Evaluation of the performance of a whole-body human dust exposure chamber is presented in this report. METHODS: The volume of the chamber is 2.13 m3 and it is operated at a flow rate of 1.0 m3/min. Makeup and exhaust air were filtered. A Wright Dust Feeder was used to generate fly ash, the testing agent. An elutriator was used to maintain particles in the respirable range. A Rupprecht and Patashnick PM-10 TEOM, a direct reading instrument, was used to monitor particle concentration. Particle size distributions were determined by a QCM cascade impactor. The evenness of dust concentrations in the chamber was determined gravimetrically. RESULTS: Dust concentrations measured at different points within the chamber were associated with variability less than 10%. Dust concentrations measured by the TEOM, in µg/m3, at 0.2, 0.4, 0.8 and 1.6 RPMs of the Wright Dust Feeder, were 110 ± 2.8, 173 ± 8.5, 398 ± 20 and 550 ± 17, respectively. Particle size distributions (MMD and GSD) were 1.27 µm and 2.35, 1.39 and 2.22, 1.46 and 2.08, 1.15 and 2.2, respectively. Total dust concentrations measured gravimetrically in µg/m3, were 135 ± 21, 200 ± 35, 333 ± 18 and 891 ± 27, respectively. CONCLUSION: The whole-body human exposure chamber offers several advantages and has better performance than most of the inhalation challenge systems previously described.
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. This article is a report on the performance of the system with gas phase agents. Results of the performance of the system with particulate phase agents will be presented in a separate report. The chamber was constructed from Plexiglas with a volume of 2.13 m(3) (75 ft(3)) and operating at a flow rate about 1.0 m(3)/min (34 cfm). Both the makeup and exhaust air were HEPA-filtered. CO(2) was used as a tracer gas and its concentration was measured using Metrosonics aq-5000 instruments. The CO(2) concentrations used in this study ranged from about 5000 to 12,000 ppm. Observed and predicted concentrations at equilibrium of test material were in agreement within 1.7%. Concentration of CO(2) was found to be even horizontally throughout the chamber, with a small initial lag of about 30 sec between the maximum concentration at the top and the bottom of the chamber. The system can thus be reliably used for inhalation challenge procedures for gases.
