Masks with these one-way valves expel respiratory droplets from the wearer into the air.
Source: https://www.livescience.com/avoid-masks-exhalation-valves-cdc-recommends.html
Only the Autodidact is Free
Masks with these one-way valves expel respiratory droplets from the wearer into the air.
Source: https://www.livescience.com/avoid-masks-exhalation-valves-cdc-recommends.html