Any loud talker, or huffer and puffer is likely saying it and spraying it all over your face if you're near and right out into the airwaves when they open their mouth with any exertion and force. If you dont believe me, take a moment to look when a certain light illuminates what's flying in the air. Dust is constantly floating. When a person scratches themselves, it releases dried up skin into the air. And if you watch that light when certain people talk, you'll see little mists entering you air bubble.