PPE masks do not always prevent spread of airborne diseases

A high percentage of health care workers are at risk of contracting airborne diseases such as COVID-19 due to personal protective equipment facemasks not fitting correctly, according to a review of literature carried out by researchers from The University of Western Australia, Perth Children’s Hospital and Fiona Stanley Hospital.

Published in Anaesthesia (will be made live when embargo lifts), the researchers examined the literature around N95 and P2 facemasks commonly used by health care workers as a means of protection, and found women and Asian health care workers were most at risk from facemasks not fitting properly.

They examined the importance of fit testing (a standardised test to assess if the mask fits the wearer properly) and fit checking (where the wearer feels for air leakage around the mask) for the protection of health care workers against airborne diseases.

“In the COVID-19 environment, it’s particularly important to ensure masks fit correctly, which is the last line of defence for health care workers.”

Professor Britta von Ungern-Sternberg

The review found initial fit-pass rates for women varied between 40 and 90 per cent while an average of 60 per cent was recorded in fit pass rates in Asian women. Fit pass rates were higher among men and in Caucasians compared to Asians.

Professor Britta von Ungern-Sternberg from UWA’s Medical School, who is the Chair of Paediatric Anaesthesia, said many masks were falling short because one size did not fit all.

“It’s important that health care workers are checking their face mask when they put it on, but also regular fit testing of masks is needed to ensure there are no leaks that are often too small for health care workers to pick up with simple fit checking,” Professor von Ungern-Sternberg said.

“Performing a self-test to check if they can feel a leak should be carried out each time a health care worker puts on a mask but it is not reliable in detecting proper fit or leak and should not replace fit testing.”

“The review also shows respirators fitting correctly is far more important for airborne protection than the filtration capacity of the material.”

Clinical Associate Professor Adrian Regli, an Intensive Care Consultant at Fiona Stanley Hospital, said when masks did not fit properly, leaks could occur allowing airborne diseases to enter, resulting in decreased protection of individuals.

“In the COVID-19 environment, it’s particularly important to ensure masks fit correctly, which is the last line of defence for health care workers,” Professor Regli said.

The authors say the review highlights that fit testing should be conducted annually, in line with national and international recommendations. They hope the review provides an important insight for medical practitioners, policy makers and government to help develop ways to improve safety and improve protection of front line workers.

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