The mattress is, without a doubt, the dirtiest object we have close contact with during 1/3 of our lives. The causes of this unhygienic and health threatening state of affairs are numerous and complex. Men, women and children spend years on mattresses that are extremely soiled and thus dangerous to their health. It is erroneous to believe that a sheet will protect against this kind of dirt. The dirt consists of micro particles (1 - 20 microns). A bed sheet protects against these particles about as much as a fishing net would protect against sand.