Fit testing checks that the mask seals. The medical evaluation checks that the person can safely breathe through it for a shift. The standard puts the second one first.
Before anything else. The employer shall provide a medical evaluation to determine the employee's ability to use a respirator, before the employee is fit tested or required to use the respirator in the workplace; evaluations may be discontinued when the employee no longer has to use one (29 CFR 1910.134(e)(1)).
How. The employer identifies a physician or other licensed health care professional (PLHCP) to perform the evaluation using a medical questionnaire or an initial medical examination that obtains the same information (29 CFR 1910.134(e)(2)(i)); the questionnaire is Sections 1 and 2, Part A of Appendix C ((e)(2)(ii)). A follow-up examination is required for any employee who answers yes to certain questions or whose initial response indicates a need (29 CFR 1910.134(e)(3)). The questionnaire and examinations are administered confidentially, during normal working hours or at a time and place convenient to the employee, in a way the employee understands (29 CFR 1910.134(e)(4)), and at no cost.
What the employer gives and gets. The employer must supply the PLHCP with the type and weight of respirator, duration and frequency of use, expected effort, additional protective equipment, and temperature and humidity extremes (29 CFR 1910.134(e)(5)). What comes back is a written recommendation limited to whether the employee is medically able, any limitations, and the need for follow-up — not the medical findings themselves (29 CFR 1910.134(e)(6)).
Again when. The standard does not set an annual repeat. Additional evaluations are required when an employee reports signs or symptoms related to respirator use, when a PLHCP, supervisor or program administrator says one is needed, when information from the program including fit-test observations indicates a need, or when a change in workplace conditions substantially increases the physiological burden (29 CFR 1910.134(e)(7)).
Voluntary use of filtering facepieces is the one place this does not apply: Appendix D goes to the employee instead, and no evaluation is required for that use alone.