Governments, the mainstream media, and institutional propagandists can decide to operate in a science vacuum, or select only incomplete science that serves their interests. By making mask-wearing recommendations and policies for the general public, or by expressly condoning the practice, governments have both ignored the scientific evidence and done the opposite of following the precautionary principle.
You should know that there is no known benefit arising from wearing a mask in a viral respiratory illness epidemic.
When you hear one of those talking heads on TV say that scientists agree that face-masks are effective in preventing the spread of Covid-19, you should be asking them to provide their evidence. They can’t because it doesn’t exist. All you hear is their opinion or some twisted interpretation of what somebody else said.