Aeroplanes exchange air ten to 20 times per hour a ha, so it's incredibly powerful at exchanging air. The person that is the most vulnerable on an aeroplane is probably the row in front of it. People who are ten rows behind you really don't affect you, and vice versa. If i am wearing a pretty well fitted kand 95 or 95 mask, wth like a flexible nose that has a little bit of cushion so i can count ot nicely fit it around my nose, that's pretty darn good protection. It's not perfect, but it probably gives you about 90 to 92 % protection from any viral particles getting to your nose and mouth.