Yep.
It's in the scientific literature. By scientists. Guess how we know you aren't a scientist?
From one of the cites:
facemasks worn by infected persons are potentially an effective means of limiting the spread of influenz
"
And this:
Surgical masks worn by patients reduce aerosols shedding of virus.
And this:
In a study by Milton et al. [24], they have investigated the effects of using surgical masks in preventing the aerosols influenza transmission. The obtained results indicated that surgical masks had prevented the viral detection aerosols by 25-fold for the coarse aerosols, and 2.5-fold for the fine particles, hence, generally 3.4-fold reduction was reported for the exhaled aerosols.
Which means that masks can be useful in limiting spread of viruses. As experience has shown to be true. Would you like me to show you again? O.K.
States with lowest infection rates:
Hawaii 316
Vermont 333
Alaska 411
Oregon 544
Only Alaska lacks a mask mandate, among these.
...
Not so good states:
Tennessee 114,539
Utah 116,794
Rhode Island 120, 124
South Dakota 128,160
North Dakota 131,691
All these states except Rhode Island lack mask mandates.
Not just experimental evidence, but confirmation in a real epidemic.
That's how science works dude. That's how we know you aren't a real scientist. You don't have a clue about the way it works.