What would you consider “applicable safety equipment that may be worn during actual respirator use which could interfere with respirator fit” (Sweating the small stuff series)

Bear with me on this, as I know this is getting deeper than most think about Respiratory Protection. But the vast majority of the people I train and fit test are personnel who enter/work in IDLH environments, so I get very picky about my RP practices.

OSHA’s long-standing Fit Test Procedures in Mandatory Appendix A state:

13. The fit test shall be performed while the test subject is wearing any applicable safety equipment that may be worn during actual respirator use which could interfere with respirator fit.

The question is, what would you consider…