Aerosol blocking assessment by different types of fabrics for homemade respiratory masks: spectroscopy and imaging study

Foschini, M.; MONTE, A. F.; Mendes, A. C.; Scarabucci, R. J.; Maletta, A.; Giuliani, C. D.; Duarte, B. A.; Del-Claro, K.

During the COVID-19 pandemic, there is no agreement, until the current date, about the recommendations of homemade face mask use for the general population, and one of the reasons is a lack of information about their real protective rule on spreading aerosols and viruses. This is a comparative study regarding the relative efficiencies of commercial respiratory masks (medical masks) and homemade fabric masks, which may guide authorities across the globe, following the 'Advice on the use of masks in the context of COVID-19', by the World Health Organization. We described two optical methodologies for charactering respiratory masks. It happens that the aerosol scattering coefficient is linear as a function of its concentration inside the mask chamber. Quantitative optical properties of scattering for a large batch fabrication of masks were demonstrated, making the mask N95 suitable for use as a reference standard.