Particle size, filter media hole size, bypass. It really is that simple. Even HEPA filtration is not 100% first pass capture. There are filtration test reports available. Really no need to guess.
If masked really worked and the only objective of the government was to require mask to stop the spread of the virus why hasn’t the government issued strict mask standards for the type of mask warn? The government In Michigan and every other states and now Biden’s federal land “mask mandates” have zero guidelines for the type of mask. It can be a gas mask, a bandanna or anything in between and the government doesn’t care because it’s about compliance and control not mask effectiveness.
