For example, with the hepatitis viruses, it was not uncommon years ago, before the science and art of biosafety got implemented into primate laboratories, that the animal handlers of animals used for Hepatitis A or B research or animals that were indigenously infected with those viruses, were all seropositive for antibodies to these agents. In this instance, face protection means sturdy face shields or perhaps safety glasses. For respiratory protection, the principle is, if there is an agent that is known to be transmitted by the airborne route, then respiratory protection must be implemented. There are some definite principles to adhere to. It is not just putting on a wraparound surgical mask.
Surgical masks are for doing surgery.
Respiratory protection means that respirators ought to be used. In biosafety level 3 facilities there are indigenous or exotic agents with a potential for aerosol transmission and the disease may have serious health effects. Specific mention is made about goggles, masks or face shields, and respiratory protection when aerosols cannot be safety contained. Under ordinary circumstances, the types of procedures that are done with these animals, are done within a barrier. In other words, the risk is supposedly designed out.