This study found neck gaiters were about 47% effective at source control (stopping you making someone else sick). While they didn't look at it, if it was well sealed around the nose it would probably be similarly effective for personal protection. A sealed n95 is going to be 95%+ effective, and wearing no mask at all will be 0% effective. So a neck gaiter is going to better than nothing, but it's not a substitute for a n95 (or even a surgical mask) in risky situations e.g. close quarters, poorly ventilated spaces (busses, bathrooms) etc. Outside, ventilation is much much better, so it probably doesn't matter as much what you wear.
argenbar t1_j3f7lne wrote
Reply to Are gaiters at least partially effective at blocking aerosols? by Lokarin
This study found neck gaiters were about 47% effective at source control (stopping you making someone else sick). While they didn't look at it, if it was well sealed around the nose it would probably be similarly effective for personal protection. A sealed n95 is going to be 95%+ effective, and wearing no mask at all will be 0% effective. So a neck gaiter is going to better than nothing, but it's not a substitute for a n95 (or even a surgical mask) in risky situations e.g. close quarters, poorly ventilated spaces (busses, bathrooms) etc. Outside, ventilation is much much better, so it probably doesn't matter as much what you wear.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9345365/