Disposable medical procedure masks are commonly worn in health care and public settings during the COVID-19 pandemic. The Filtered Filtration Efficiency (FFE) for procedure masks is generally below that of high-efficiency N95 respirators certified by the US National Institute for Occupational Safety and Health and foreign-sourced equivalents (i.e., KN95). However, many procedure masks available to the public are constructed with nonwoven polypropylene, the same highly efficient filtering medium used in respirators. In fact, enhancements that improve the seal between the mask and the face dramatically improve FFE performance, suggesting that fit, not material, is the intrinsic limiting factor for procedure masks.

Results of this study published in JAMA Network, demonstrated that wearing a medical procedure mask underneath a cloth mask provided the best improvement to FFE of all the combinations evaluated. The improvement in the FFE of procedures masks when doubled or when worn underneath reusable cloth face coverings is consistent with minimizing leaks between the mask and facial skin, including the bridge of the nose.

Although global vaccination efforts against SARS-CoV-2 are underway, the public is urged to continue using face masks as a primary intervention to control transmission.

Stay well, mask up, and stay tuned!