Medical Face Masks Do Not Affect Acid–Base Balance Yet Might Facilitate the Transmission of Staphylococcus aureus in Hospital Settings during the COVID-19 Pandemic

Introduction: Due to the SARS-CoV-2 coronavirus pandemic, the wearing of masks has become a common phenomenon. Most of the undesirable effects of using a protective face covering are usually related to the prolonged time of its wearing, and the adverse consequences of face coverings should be considered two-fold. The aim of the study was to evaluate the rate of contamination of the three types of face coverings (surgical, N95, and FFP2 masks) with the microorganism—aerobic bacteria, yeasts, and molds—after the 3 h exposure time. The study aimed to investigate the effects of wearing FFP2 masks (KN95) on respiratory function and the acid–base balance of the human body. Results: The presence of S. aureus was confirmed in both nasal carriers and non-carriers which may demonstrate the cross-contamination and spread of this bacterium via hands. S. aureus was found on external and internal surfaces of face masks of each type, and therefore could also be transmitted via hands from external sources. The 3 h exposure time is not sufficient for Gram-negative rods and mold contamination. Moreover, there were no significant differences in most of the parameters studied between the first and second examinations, both in spirometry and capillary blood gas analysis (p > 0.05).