3. Whether the NIOSH protocol determines the fit test on a product ?

Yes, for Filtering Facepiece Respirators that must be fit tested prior to use, the following Occupational Safety and Health Administration (OSHA) reference must be included in the user instructions:

Before occupational use of this respirator, a written respiratory protection program must be implemented meeting all the local government requirements. In the United States, employers must comply with OSHA 29 CFR 1910.134 which includes medical evaluation, training and fit testing.-Reference CFR 42 Part 84.