Some of the comfusion here is that the OSHA respiratory standard does not address well when a respirator is needed for biological agents. You can measure a chemcial and find if the levels are above a threshold limit. This is not possible for biologicals. Up to the H1N1 pandemic, the general rule was you use a respirator of N95 or greater (remember N95 is the LOWEST level of protection for a particulate respirator) for airborne infectious agents. These included TB, Measles, Mumps, SARS, smallpox, varicella. You will need to work with your infection prevention personnel to identify what agents your employees may be exposed to. For most healthcare facilities, the primary one is TB. Only emplyees who are expected to be exposed to airborn infectious diseases need to be fitted for a respirator. Unless we see H1N1 again, we are limiting our fit testing only to those areas where we have a greater potential for seeing TB. Areas like ER, urgent care are fitted annually. Groups like respiratory therapy,and phlebotomy are also fitted annually in our facility. In a hospital, you would also look at any staff that may enter a negative pressure room when patients are present.