We would like to discuss the letter from Lazaridis et al., “Double-surgical-mask-with-slit” method: reducing exposure to aerosol generation at upper gastrointestinal endoscopy during the COVID-19 pandemic” [1]. The authors noted that “Despite its snug fit, the narrow slit still allows easy passage of the endoscope and any required suction of the oral cavity, while the double mask itself (and its curtain-like slit) minimizes any ‘leakage’ of generated aerosols” [1]. The main question here is whether or not doubling or even tripling of masks can help to increase protection from aerosols containing pathogens. The material used for mask production is an important determinant regarding protection. In general, the size of the virus is extremely small and it might pass through the pores of a face mask [2]. This is an important physical limitation of mask use with regard to protection from COVID-19 [2]. The number of layers of face masks can contribute nothing to protection if the pore size of the mask at all the layers is still larger than the pathogen. The use of negative pressure rooms for patient care might be a more effective measure for controlling the spread of disease.
