There are numerous studies out there, but Steve (and anyone) is capable of searching for them. Living in the USA with its conspiracy theories and batshit crazy ideas, you can't dissuade people who believe that praying to little baby Jesus will prevent Covid because they're crazy. You can't convince people who rely on faith-based "medicine" that they're wrong, becausethey're crazy. You can't convince people who won't listen that "well documented" means there have been studies out the wazoo proving masks are effective that you're right, because they don't WANT to believe it. It's disappointing (I'm actually surprised), but there's a time to give up trying. Argument never changes anyone's mind.