[Analysis of the Adjustment of Self-Filtering Masks in Combination with Surgical Masks for the Protection of Health Professionals in the Care of Patients Affected by SARS-COV-2 from an Experimental Study].

Introduction: Frontline healthcare workers have a high risk of exposure to SARS-CoV-2 coronavirus, which causes COVID-19. The use of appropriate personal protective equipment (PPE) is essential to prevent this occupational disease. Surgical masks and filtering face piece (FFP) respirators are important parts of this PPE. European standard EN 149 establishes three protection levels for FFP respirators (FFP1, FFP2, FFP3), depending on the particle infiltration degree through their materials, and these, in turn, are based on their filtration effectiveness. The aim of this laboratory test is to determine and quantify the filtration and fit rate of different FFP respirators, singly and in combination with surgical masks, by performing a series of fit tests and consequently, to check whether this combination improves protection levels for healthcare workers who care for COVID-19 patients.

Material and methods: Several FFP respirators and surgical masks, singly and in combination, were fit tested with a PortaCount Pro + 8038, which fulfills OSHA standards, in a series of tests performed on healthcare workers in seven different breathing situations when taking care on COVID-19 patients, in order to determine and quantify their fit to the workers' face.

Results: Wearing a surgical mask together with a highly efficient FFP respirator provided increased respiratory protection. Interestingly, one of these highly efficient FFP models, combined with a surgical mask, achieved a protection factor over 200 (whereas 100 is the minimum required protection factor).

Conclusions: Surgical masks, when used together with a FFP2 respirator, could significant ly improve the degree of fit of all self-filtering face piece by providing greater filtration efficiency and greater user protection from exposure to aerosols.