The Diagnostic Instrumentation and Analysis Laboratory (DIAL) at Mississippi State University was awarded a project to study the feasibility of measuring particulate matter downstream of a high efficiency particulate air (HEPA) filter by testing commercially available equipment used to monitor the downstream side of a HEPA filter. In order to perform the work required for this project, a test stand to accommodate a 12? x 12? x 11.5? HEPA filter with a rated flow of 250 standard cubic feet per minute (scfm) was constructed. The test stand required an aerosol generator capable of producing a mass loading rate of 30 mg/m3 of dry aerosol at the face of the HEPA filter. It was determined that there was not a commercially available aerosol generator that quite fit the needs of the project. Therefore, it was necessary to develop an aerosol generator with the capabilities required for the project.

The purpose of this research was to evaluate the capability and performance of the University of South Florida’s (USF) Human Exposure Chamber (HEC) using aerosols in the thoracic range. The goals of this research were two-fold: to obtain an average particle size of 10 µm (thoracic-size range) inside the chamber during dust production and to test for evenness of dust concentration within the chamber. The USF HEC can be used for studies using gases and/or particulates. The chamber measurements are 4.16 ft x 2.67 ft x 6.75 ft, for a total volume of 75 ft3 or 2.13 m3. This research has public health significance since outdoor air pollution is found most commonly in the thoracic size range; future studies with the HEC could focus on the impact of outdoor air pollution on human subjects under various exposure conditions, and various particle size ranges. Soda lime glass beads were used in this study due to their uniformity in shape and size. A Wright Dust Feeder (WDF) was used to generate the glass beads aerosol in the chamber. Nitrogen gas and HEPA-filtered fresh air were used to transport the aerosol through the system and into the chamber. A total of nine different chamber configurations were made in order to increase the average particle size closer to the goal of 10 µm. Chamber reconfiguration provided statistically significant effect on increasing particle size with the exception of two intermediate settings. It was concluded that aerosol distribution within the chamber was even during operation of the chamber, and modification steps utilized in the study provided size distribution within +/- 6% of the target particle size.