> why we were told to wear masks that were ineffective at blocking viruses?

Masks and HEPA filters can block droplets that contain viruses. Neither filters out actual virus particles.

Respiratory virus particles outside an aerosol droplet don't last long, but yes, they should be filtered too (not "blocked", it will always be probabilistic)

▲

JumpCrisscross a day ago | parent [-]

> they should be filtered too (not "blocked", it will always be probabilistic)

The article’s point is we haven’t precisely studied what those probabilities are.

	▲	vintermann a day ago \| parent [-]
		No it isn't actually, those kind of low level technical questions have been somewhat studied. It's the end to end interventions which have been poorly studied.