I watched a segment of unknown things making you sick. One was dirty shower heads. Those are supposed to be washed overnight in vinegar once a month. Wherever I lived, the shower heads were not cleaned that often. After 1 week of not taking a shower (for an allergy patch test), I noticed the raw skin on my top lip healed. However, the bottom lip still peeled. Raw skin is usually a sign of an allergy. I could have been allergic to all the germs showering on me from the shower head. I do not know why my top lip healed that week.
I am just putting this information out there on hidden dangers. More sensitive individuals with allergies may be more at risk.