From the beginning of the pandemic, we know that wearing a mask protects other people from your own droplets. But shouldn’t masks also protect the consumer? At first, science was not available to answer this question, but it is probably true. CDC soon updated their mask tips note that the defense seems to be going in both directions.
The masks also help to reduce the inhalation of these droplets by the user (“personal protection filtration”). The benefit of the masking community to control SARS-CoV-2 is due to the combination of these effects; the benefit of individual prevention increases with the number of people who use masks consistently and correctly.
This understanding does not change the bottom – we all have to wear masks when communicating with people outside our household, but it helps to understand where protection comes from.
For example, if you are heading to a place where you know that many other people will not wear a mask, does it matter if you wear one yourself? If masks only protect others from you, you would do a small favor to other people, but not help yourself. If the new interpretation is correct, wearing a mask in this situation is likely right help protect you.
So what has changed?
First, scientists study the specifics of how masks work, including how droplets behave when they encounter different types of mask materials. The droplets can stick to the fibers, be repelled by them or caught between them. Even small particles can be captured by masks. (There ‘s great visualization of how it works in the New York Times.) This supports the idea that masks help no matter which side the virus-laden particles come from.
The other line of evidence is a series of cases: places where you would expect more transmission of the virus, but because wearing masks is common, the transmission rate is particularly low. These tests include hairdressers who worked while they were symptomatic and an outbreak on board an aircraft carrier. From this type of research, we can’t be sure how much protection comes from the user’s mask compared to everyone else’s masks, but it adds to our understanding that more masks make the environment safer.
The bottom line is that the masks work, although they are not perfect. The N95 works better than fabric masks, but many fabric masks are still very effective, depending on their design. (More layers and more threads seem to create a more protective mask.) So wear your mask, even if the others aren’t; it will still help.