/The study evaluates the filter efficiency of 227 types of masks sold in Brazil – 05/03/2021 – Equilíbrio e Saúde The study evaluates the filter efficiency of 227 types of masks sold in Brazil – 05/03/2021 – Equilíbrio e Saúde ksuadminMay 3, 2021 49 The new coronavirus is mainly transmitted through inhalation of droplets of saliva and respiratory secretions suspended in the air. Because of this, wearing masks and maintaining social distance are the most effective ways to prevent Covid-19 while there is no vaccine for everyone. Inexpensive, reusable and available in different colors and prints. Cloth masks are most commonly used by Brazilians. However, the ability to filter aerosol particles with a size equivalent to that of the new coronavirus can vary between 15% and 70%, according to a study at the Institute of Physics at the University of São Paulo (IF-USP).