1/ Even mediocre masks have a significant benefit if EVERYONE wears one. Everyone is needed to assure those infected are wearing one, too. Consider the following relatively mediocre mask (or poor fit on good masks) scenario.
2/ Assume everyone in an indoor space wears a mask that is only 40% efficient, i.e., 40% efficient at reducing emissions from an infected person & 40% efficient at reducing uptake by a receptor. What's the net benefit to those who are susceptible?
3/ 40% + (0.4 x 60%) = 64%. Just having everyone wearing mediocre masks (or better masks with poor fit) leads to a 64% reduction in inhaled dose of virus-laden aerosol particles. Lowering inhaled dose this much may stave off infection and save lives.
4/ Now, what if we double the efficiency to 80% (better masks or improved fit). In this case the reduction in inhaled dose is 80% + (0.8 x 20%) = 96%. Let that sink in - an over 20 fold decrease in inhalation dose. That is substantial protection & we are not even close to N95.
5/ The actual inhaled dose is a function of particle size and thus particle size distribution, but the relative impact of masks does not change from this simple analysis. Everyone wearing a mask dramatically reduces inhaled dose. Period.
6/ Multi-layered cloth masks made of the right material and with good fit can easily lead to 90 to 96% overall reduction in inhaled dose if EVERYONE in the indoor space wears one.
7/ This is cheap, low-tech, and easy folks, and will protect you, your friends, family, classmates, colleagues, community, businesses, health care workers, and country. Just do it!
8/ If you are vaccinated it will protect you from a breakthrough infection & potential to infect someone else who is unvaccinated. If you are not vaccinated, please do so. Wearing a mask before you do may save your life, but will also protect (see list above).
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