I just saw a post about "If a fart can make it through underwear and a pair of jeans, how can a mask made of cloth save you from covid? Asking for a friend..[sic]" Well, firstly, thank you for the question! As a scientist (specifically a chemist, I am absolutely qualified to 1/9 answer this question! Let's consider the size of the molecules that make up the stink smell in farts. We'll focus on one particular example, as the others are similarly sized (when compared to the size of a virus). Methanthiol (CH3SH), like a number of thiol (-SH) containing 2/9