I guess I need to post this again:
Three most common types of masks:
Surgical procedure masks
Surgical procedure masks do not seal around the edges, so not all incoming air is filtered. They have no rating for the percentage of particulate matter filtered out of incoming air. They only offer minimal protection to the wearer and mainly protect others from the wearer coughing and sneezing by catching ballistic droplets being sprayed out by the wearer. This is the type of mask recommended for the general public, and the purpose is to prevent asymptomatic carriers from inadvertently spreading aerosolized viruses by coughs and sneezes. Some aerosolized viruses can still escape, but they cut way down on the amount. When it was thought that most people that were infected with COVID-19 were symptomatic, and knew they were sick, it was not recommended that the general public wear them because they gave a
false sense of security, thinking it was protecting them from aerosolized viruses when it
wasn't.
Vented Respirators
Vented Respirators ONLY PROTECT THE WEARER because the vents allow unfiltered aerosolized viruses to escape. They are designed to seal around the edges so all incoming air is filtered and they have a rating for what percentage of particulates are filtered out. This is what healthcare workers wear to protect themselves and are prioritized for healthcare use and not sold to the general public right now in the US. Because of the vent, these are much more comfortable to wear for long periods than unvented respirators and moisture doesn't build up in the filter material.
Unvented Respirators
Unvented Respirators protect both the wearer and others from the wearer, but are not meant to be worn for long periods of time. Like the vented respirators they have a rating for what percentage of particulates are filtered out. Breathing is more difficult and moisture builds up in the filter and blocks it after being used for long periods of time. When this happens air leaks around the edges of the respirator and breathing becomes progressively more difficult. Some healthcare workers are wearing these because of the shortage of vented respirators, but when worn for long periods of time are neither comfortable nor effective. This is the
ONLY type of mask that protects both the wearer, and others from the wearer.