Máscaras do Bem: An analysis of face-mask performance from a volunteer mask-making initiative in Ribeirão Preto, Brazil.

While performance was inferior to standard comparators, the masks investigated in this study afforded a level of protection in the absence of alternatives, especially in non-aerosol generating contexts. The findings of this study are useful for communities with limited resources in other developing countries. In addition, insights can be gained from the experiences in Ribeirão Preto in terms of how to respond to future health emergencies.