Maybe this might help I was sitting next to a guy in class and he had bad breath cause when I talk to him I noticed a certain smell I know what it is cause sometimes i get the same thing it's those little white things in the back of your tonsils I dont know what their actually called some people say tonsililiths (spelling doesnt count for me) or bacteria deposits, sulfer deposits whatever I just know I get them sometimes If you ever take a Q- Tip and scrape one out and smell it, it smells really awful and it's a certain smell I can tell when I talk with other people that have it but getting to my point you know when you yawn but dont open your mouth to yawn well he did that and the smell that came from him exhaling from his nose was that same smell, but as of across the room the farthest away I could smell it from someone was about 5 feet away even if they just breath through their nose