RT Journal
A1 Palen TE, Felix KG
T1 SUrgical masks vs n95 respirators for preventing influenza
JF JAMA
JO JAMA
YR 2010
FD March 10
VO 303
IS 10
SP 937
OP 939
DO 10.1001/jama.2010.192
UL http://dx.doi.org/10.1001/jama.2010.192
AB 
The need for N95 respirator fit testing adds considerable cost to the higher cost of the device itself. However, the article did not state whether the users received training in how often to change either the surgical masks or the N95 respirators. If they did receive such training, it would be helpful to know if the trained auditors collected information regarding whether the nurses changed their masks or respirators at appropriate intervals.