Skull Caps With Respirators

[MARK.A.FRIEDMANN2@ucm.com]

     Is anyone aware of a regulation, or industry standard, which would 
     prohibit wearing a skull cap (or beanie) with respirators,
providing 
     that it does not interfere with the facial seal.  It is a practice
to 
     sometimes wear a skull cap underneath the straps to prevent the
straps 
     from pulling the hair.  I have not found anything which would
prohibit 
     this, as long as the integrity of the facial seal is maintained.
     
     Thanks in advance.
     
     
     Mark Friedmann
     mark.a.friedmann2@ucm.com
     815-942-2920  X3565