which bsl level is for lethal agents for which there are no vaccines or other countermeasures
Biosafety level Biosafety level 4 (BSL-4) is the highest level of biosafety precautions, and is appropriate for work with agents that could easily be aerosol-transmitted within the laboratory and cause severe to fatal disease in humans for which there are no available vaccines or treatments.[8] BSL-4 laboratories are generally set up to be either cabinet laboratories or protective-suit laboratories.[8] In cabinet laboratories, all work must be done within a class III biosafety cabinet.[8] Materials leaving the cabinet must be decontaminated by passing through an autoclave or a tank of disinfectant.[8] The cabinets themselves are required to have seamless edges to allow for easy cleaning. Additionally the cabinet and all materials within must be free of sharp edges in order to reduce the risk of damage to the gloves.[8] In a protective-suit laboratory, all work must be done in a class II biosafety cabinet by personnel wearing a positive pressure suit.[8] In order to exit the BSL-4 laboratory, personnel must pass through a chemical shower for decontamination, then a room for removing the positive-pressure suit, followed by a personal shower.[8] Entry into the BSL-4 laboratory is restricted to trained and authorized individuals, and all persons entering and exiting the laboratory must be recorded.[8]