Simulated Workplace Protection Factors for Half-Facepiece Respiratory Protective Devices

Abstract

This study investigates two different methods (random effects model and 5th percentile) for determining the performance of three types of respiratory protective devices (elastomeric N95 respirators, N95 filtering-facepiece respirators, and surgical masks) during a simulated workplace test. This study recalculated the protection level of three types of respiratory protective devices using the random effects model, compared the two methods with each other and the APF of 10 for half-facepiece respirators, and determined the value of each of the fit test protocols in attaining the desired level of simulated workplace protection factor (SWPF). Twenty-five test subjects with varying face sizes tested 15 models of elastomeric N95 respirators, 15 models of N95 filtering-facepiece respirators, and 6 models of surgical masks. Simulated workplace testing was conducted using a TSI PORTACOUNT Plus model 8020 and consisted of a series of seven exercises. Six simulated workplace tests were performed with redonning of the respirator/mask occurring between each test. Each of the six tests produced an SWPF. To determine the level of protection provided by the respiratory protective devices, a 90% lower confidence limit for the simulated workplace protection factor (SWPF _LCL90% ) and the 5th percentile of simulated workplace protection factor were computed. The 5th percentile method values could be up to seven times higher than the SWPF _LCL90% values. Without fit testing, all half-facepiece N95 respirators had a 5th percentile of 4.6 and an SWPF _LCL90% value of 2.7. N95 filtering-facepiece respirators as a class had values of 3.3 and 2.0, respectively, whereas N95 elastomeric respirators had values of 7.3 and 4.6, respectively. Surgical masks did not provide any protection, with values of 1.2 and 1.4, respectively. Passing either the Bitrex, saccharin, or Companion fit test resulted in the respirators providing the expected level of protection with 5th percentiles greater than or equal to 10 except when passing the Bitrex test with N95 filtering-facepiece respirators, which resulted in a 5th percentile of only 7.9. No substantial difference was seen between the three fit tests. All of the SWPF _LCL90% values after passing a fit test were less than 10. The random model method provides a more conservative estimate of the protection provided by a respirator because it takes into account both between- and within-wearer variability.

Keywords:

• fit test
• N95 filtering-facepiece respirators
• N95 elastomeric respirators
• simulated workplace test

ACKNOWLEDGMENTS

The authors wish to acknowledge the following individuals for contributions to this manuscript: Matthew Zack, Robert Gerzoff, and James Wassell for their input on the statistical analysis; Donna Simms, Howard Shen, Jeremy Myers, Jose Hernandez, Timothy Dawson, Tracey Prinsloo, and Yolanda Ward for helping to perform the respiratory protective device testing. The authors also wish to thank Donald Campbell for his assistance in the development of the testing protocol, and John Neuhaus for providing a copy of his program.

Mention of commercial product or trade name does not constitute endorsement by the Centers for Disease Control and Prevention or the National Institute for Occupational Safety and Health.

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health

Notes

^A The percentage of subjects having their SWPF values below a target APF.

^B The percentage of subjects having more than 5% of their SWPF values less than the specified value.

^C All filtering-facepiece and elastomeric facepiece models combined.