you realize you breathe in way more nasty nasty microparticles going outside for like 3 min that you do from your toilet flushing a couple of times a day? lots of fungus, bacteria, viruses, spores, etc.

your immune system exists dude. and it needs light exercise.

the only way aerosolized waste is making you sick is if you like go inside a sewer or waste disposal tank where it's intensely concentrated, and it's really the methane that's doing you in, as the bacteria don't float.

also your basic breathing through your nose and mouth is shooting out way more nasty shit that actually can infect other people. by paranoid logic we should all be using closed breathing systems at all times.