Ever shined a powerful flashlight or laser around and seen all the particles floating in the air? You can also see them sometimes with a particularly bright sun beam coming through a blind. While these visible particles probably aren’t spores, it does illustrate how much stuff you’re constantly breathing in. There is no escaping. You’re part of life, there’s billions of organisms on you and in you at all times, and they’re fighting for survival too. There’s no escape. The only reason you survive is because of your immune system, and that’s why immunodeficient people like severe burn victims and AIDS patients just die despite nothing particularly “wrong” happening to them.