Since people still don’t understand how to interpret what science says about masks, let me explain.
Masks. Are. Source. Control.
If someone tells you that masks don’t work, you can respond by asking, “what is the purpose of the mask?” If they respond with something like “protect the wearer from infection,” they are wrong. The purpose of a mask is to reduce the amount of virus you spread. Source control.
When someone is infected, they can shed viral particles out of their mouth & nose in the form of droplets and aerosols. These particles can linger in the air for varying amounts of time. When the air is saturated with enough particles you can become infected by breathing them in.
Masks reduce the number of particles that you spew out into the air every time you cough, sneeze, talk, and breathe. This means it takes much more time to saturate the air with enough virus to infect someone else. This making masks especially useful in poorly ventilated areas.
Can this be measured in a community setting? Yes, but it’s hard to do those experiments. They have been done in some form, though. And they support that masks offer a benefit. https://science.org/doi/10.1126/science.abi9069
However most RCT’s and community setting observational studies are going to be better designed to answer the question of how well a mask protects the wearer and not how well they protect others from the virus the wearer is shedding. So keep that in mind when interpreting studies.
Can this be tested some other way? Yes. There are several experiments showing that masks block a significant fraction of virus-containing particles. A few examples:
Masks are a cheap and easy to use tool for *reducing* risk that we can use alongside all of our other tools to reduce risk and save lives. They’re also more comfortable than a trip to the hospital or a ventilator down your throat.
If you don’t want to wear one, fine. But don’t spread lies about how effective or ineffective they are while pretending that you’re representing the science accurately.