Evaluation of new strategies for measuring Freon-113 exposure dose to be correlated to quantitative fit factor.
Zhuang-Z; Coffey-C; Nicholson-J; Lawrence-B; Qiao-G; Campbell-D; Jensen-P
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana. Fairfax, VA: American Industrial Hygiene Association, 2001 Jun; :69
Recent NIOSH research has found correlation between fit factors of the corn oil and ambient aerosol fit-test methods and the wearers' Freon-113 exposure doses while wearing negative-pressure, half-facepiece respirators (assigned protection factor: 10). However, the biological monitoring strategies and methods for measuring exposure dose of Freon-113 need to be improved for similar correlation studies of respirators with assigned protection factors greater than 10. Thus, the purposes of this study were to develop improved biological monitoring strategies for measuring exposure dose of Freon and establish good subject characterization curves (relationship of end-exhaled air concentration to exposure dose). A new Freon-113 delivering and monitoring system was developed for this study. The system consists of three parts: a mixing chamber, a breathing mask with two-way breathing and three-way sliding valves, and an environmental chamber. Six subjects participated in this study. Freon-113 at concentrations of 0.5, 1, and 5 ppm were delivered to each subject through the breathing mask continuously for 30 minutes. Freon-113 at concentrations of 5 and 25 ppm were delivered to each subject intermittently (i.e., during the first two minutes, between 15 and 17 minutes, and between 28 and 30 minutes). End-exhaled air samples were collected from the mixing chamber every five minutes during the 30-minute exposure of Freon-113 and 80 minutes post exposure. Preliminary analyses of data indicated that more consistent end-exhaled air Freon-113 concentrations were obtained with the new system as compared to the original end-exhaled air samplers. End-exhaled Freon-113 concentration was not affected by the exposure scenarios (continuous and intermittent). The subject characterization curves were found to be improved as R-squre values were generally greater than 0.95. The new system is suitable for determining Freon-113 exposure dose while wearing respirators with assigned protection factors greater than 10.
Respirators; Respiratory-equipment; Respiratory-protection; Respiratory-protective-equipment; Aerosols; Exposure-levels; Face-masks; Biological-monitoring; Air-samples; Exposure-chambers; Exposure-methods; Air-samplers; Air-sampling-techniques
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana