Jill Walters

Project title: Evaluation of Quantitative Respirator Fit Testing of Workers Exposed to Cr VI Aerosols from Various Industrial Work Processes

Degree: MS | Program: Occupational & Environmental Exposure Sciences (OEES) - no longer offered | Project type: Thesis/Dissertation
Completed in: 2010 | Faculty advisor: Michael S Morgan


This study focuses on the welding, electroplating, and painting industries that are exposed to chromium VI compounds (Cr VI). Many industrial operations use Cr VI for its protective properties against corrosive damage. Unfortunately, when Cr VI is airborne there is an increased risk of respiratory damage, lung cancer, skin reactions, and liver and kidney damage. The main route of exposure is via inhalation. In 2006, OSHA issued a new standard that lowered the PEL for Cr VI from 50 to 5µg/m3 as an 8-hour TWA, based on the concern of the toxicity it has on the lungs and internal organs. Engineering controls are most favorable to control Cr VI exposures, but when engineering controls are not feasible or do not reduce the contaminant below the PEL, respiratory protection must be worn by the worker. For this study, quantitative fit testing (QNFT) was performed on each subject who uses respiratory protection to measure respirator performance from inhaling hazardous substances in the workplace. The ratio of the aerosol concentrations outside the respirator to the aerosol concentration inside the respirator is known as the fit factor (Cout/Cin). For a half face respirator to pass QNFT, it must have a fit factor of 100 or greater, thus ensuring the fit, model, and size is appropriate for the wearers physical face features. The fifteen subjects in this study produced a fit factor range of 188 to 29,266. However, the penetration of particles via the face seal may exhibit a dependency on particle size and aerosol concentration. Some studies suggest that Cr VI particle size differ depending on the work process. The particle size of Cr VI will determine the likelihood of the compound's disposition within the respiratory system, with the respirable fraction (particles less then 4.0 micrometers) capable of entering into the blood stream. Cr VI ambient air concentrations have shown to be correlated to chromium urinary concentrations. The specific aim of this project is to determine if the addition of respirator fit factor measurements influences the correlation between Cr VI exposures and the biological uptake by further examining the impact Cr VI size distribution and ambient concentrations has on respirator face seal effectiveness.