Good clean (messy) fun shouldn’t preclude good hygieneIngimage Ltd/Alamy By Sally Bloomfield“Two-second rule!” our children shout as they snatch food off the floor and pop it into their mouths. It is oft stated that our lives and homes are too clean, that we need to get dirtier for the sake of our health. You have probably heard it referred to as the hygiene hypothesis. This concept, first introduced back in 1989, was quite specific, proposing that rising levels of allergies might be linked to lack of exposure to childhood infections, due to higher standards of hygiene. …