Particulate face masks for protection against airborne pathogens - one size does not fit all: an observational study.

Objective: To determine the proportion of hospital staff who pass fit tests with each of three commonly used particulate face masks, and factors influencing preference and fit test results.

Design: Observational study.

Setting And Participants: 50 healthy hospital staff volunteers in an 18-bed general intensive care unit in an Australian teaching hospital.

Interventions: Participants were administered a questionnaire about mask use and their preferred mask and underwent qualitative fit-testing with each of three different particulate masks: Kimberly-Clark Tecnol FluidShield N95 particulate filter respirator (KC), 3M Flat Fold 9320 particulate respirator and 3M 8822 particulate respirator with exhalation valve. Participants who failed fittesting were trained in correct mask donning, and fittesting was repeated.

Main Outcome Measures: Proportion of participants who passed the fit test for each mask and the effect of training.

Results: The proportion of participants who passed a fit test was low for all three masks tested (KC, 16%; flat fold, 28%; and valved, 34%). Rates improved after training: the first mask tested fitted in 18% of participants pre-training and 40% post-training (P = 0.02). None of the masks fitted for 28% of participants. There were no significant predictors of fit-test results.

Conclusions: A large proportion of individuals failed a fit test with any given mask, and we were not able to identify any factors that predicted mask fit in individuals. Training on mask use improved the rates of adequate fit. Hospitals should carry a range of P2 masks, and should conduct systematic P2 mask training and fit-testing programs for all staff potentially exposed to airborne pathogens.