29CFR Part 1910.134, ,   Title 8, Section 5144

Respirators are used by American workers as a means of protection against a multitude of respiratory hazards. It is critical that respirators perform as they are designed to protect employees from adverse health effects. On July 13, 1974 the Cal/OSHA standard came into effect, and was amended on November 23, 1998.  On April 8, 1998 OSHA’s new respirator standard came into effect. It clarifies, updates, and strengthens the prior standard of 1971. It applies to general industry, construction, shipyards, marine terminals, and long shoring operations. Engineering controls to effect the work environment are to be a primary method of eliminating risk to employees, but when these prove insufficient to insure safe breathing, a respiratory protection plan must be in place. Employers are required to have a written program with worksite-specific procedures and elements for required respirator use. A program administrator is to be designated and the program shall be updated as necessary.  The Information you need to provide to us.

Medical Component
Medical evaluation to determine whether an employee is able to use your company's specific respirator in any situation one is necessary to prevent injuries, illnesses, and even, in rare cases, death from the physiological burden imposed by respirator use. Regardless of the duration or frequency of respirator use, the employer must select a Physician or other licensed health care professional to conduct a medical evaluation. This evaluation consists of either a medical questionnaire and/or a medical examination. Pertinent positive responses to questions, request by an employee, supervisor observing any problem using a respirator trigger the need for more extensive medical examination. OSHA requires initial medical evaluation to be conducted prior to fit testing to identify those employees who have medical conditions that could possibly worsen with even the limited amount of respirator use associated with fit testing.