Is dirt good for you?
Nu.nl interviewed prof. Ger Rijkers, who teaches Biomedical Science and Life Science at UCR, to assess the value of the statement: a little dirt is good for the immune system. The conclusion was that this was partially true.
The article indicates that young children need to get into contact with different micro-organisms, to train their immune system when to react and when not to. The chance of allergies is increased in extremely clean environments. This does not mean that children need to grow up in dirty surroundings, just that extreme cleanliness is not good either.
Hygiene is still important, cat poo in sandboxes can still transfer pathogens and the flu is easily spread by sneezing on your hands. It is important to clean your hands after visiting the toilet and cutting meat. There has not been much research into the effects of coming into contact with different bacteria and virusses on adults.
You can read the full article in Dutch here.