Fitting Characteristics of Eighteen N95 Filtering-Facepiece Respirators

Abstract

Four performance measures were used to evaluate the fitting characteristics of 18 models of N95 filtering-facepiece respirators: (1) the 5th percentile simulated workplace protection factor (SWPF) value, (2) the shift average SWPF value, (3) the h-value, and (4) the assignment error. The effect of fit-testing on the level of protection provided by the respirators was also evaluated. The respirators were tested on a panel of 25 subjects with various face sizes. Simulated workplace protection factor values, determined from six total penetration (face-seal leakage plus filter penetration) tests with re-donning between each test, were used to indicate respirator performance. Five fit-tests were used: Bitrex^™, saccharin, generated aerosol corrected for filter penetration, PortaCount^® Plus corrected for filter penetration, and the PortaCount Plus with the N95-Companion^™ accessory. Without fit-testing, the 5th percentile SWPF for all models combined was 2.9 with individual model values ranging from 1.3 to 48.0. Passing a fit-test generally resulted in an increase in protection. In addition, the h-value of each respirator was computed. The h-value has been determined to be the population fraction of individuals who will obtain an adequate level of protection (i.e., SWPF ≥ 10, which is the expected level of protection for half-facepiece respirators) when a respirator is selected and donned (including a user seal check) in accordance with the manufacturer's instructions without fit-testing. The h-value for all models combined was 0.74 (i.e., 74% of all donnings resulted in an adequate level of protection), with individual model h-values ranging from 0.31 to 0.99. Only three models had h-values above 0.95. Higher SWPF values were achieved by excluding SWPF values determined for test subject/respirator combinations that failed a fit-test. The improvement was greatest for respirator models with lower h-values. Using the concepts of shift average and assignment error to measure respirator performance yielded similar results. The highest level of protection was provided by passing a fit-test with a respirator having good fitting characteristics.

Keywords:

• filtering-facepiece
• fit-test
• respirator
• simulated workplace protection factor

Acknowledgments

Mention of a specific product or company does not constitute endorsement by the Centers for Disease Control and Prevention or Applied Industrial Hygiene, Inc.

Notes

^A Test not performed using this model.

^B No subjects passed the fit-test with this model.

^A One subject was not able to test this respirator and could not be replaced before end of the study.

^A Models listed in order of performance without fit-testing.

^B Total number of tests conducted for each type of fit-test.

^C Test not performed using this model.

^D One subject was not able to test this respirator and could not be replaced before the end of the study.

^A 95th Percentile total penetration values with the same letter are not significantly different.