Some single use masks are already being recycled into road making material.
This is far from a real problem, IMO. The problem if any was not enough masks, fake masks, shoddy manufacturing.
[edit- reflecting on this I do not regret buying and using masks, I do contemplate how many paper towels I use and discard when washing my hands several times a day. Using cloth hand towels would be greener, and browner, and less clean. /edit]
JR