" When we clean obsessively we do indeed get rid of everything, both bad and good. This can not be a good kind of cleanliness. As it happens the higher the hygiene standards in a country the higher that nations incidents of allergies and autoimmune diseases. The more sterile a household is the more its members will suffer from allergies and autoimmune diseases. Thirty years ago about 1 person in 10 had an allergy. Today that figure is 1 in 3. At the same time, the number of infections has not fallen significantly. This is not smart hygiene. "

― Giulia Enders , Gut: The Inside Story of Our Body’s Most Underrated Organ