Biosafety Levels 1-4
We’ve known that breathing in or touching infectious/infected material is probably bad since before germ theory, but it wasn’t until 1943 that our first formal guidelines and laboratories for technician separation from the infectious agent were set up. It was the 1960s before the first conference to standardize personal protection equipment (PPE) guidelines.
These days we have 4 basic safety levels when working with biological agents: Biosafety Levels (BSL) 1-4
BSL 1 includes well-understood agents not known to regularly affect adult humans, and which present a minimal level of hazard to the technician. Canine hepatitis, non-pathogenic strains of E. coli, and other non-infectious bacteria. Aside from standard healthy-living procedures (washing with soap etc), laboratory equipment is decontaminated via autoclave between uses, protective gloves, and sometimes protective goggles are required.
BSL 2 includes many of the milder infectious diseases that we know about, such as Salmonella, measles, mumps, MRSA, C. difficile, and hepatitis A, B, and C. These are sometimes serious illnesses, but are not easily aerosolized in a laboratory setting. When aerosols may be formed, biological safety cabinets are used, extreme care is taken with sharps, access to the laboratory is limited during work, and all technicians are trained in pathogen handling procedures.
BSL 3 includes dangerous pathogens that can cause potentially lethal infection, such as Yersinia pestis (black plague), rabies, SARS, tuberculosis, tularemia, and yellow fever. Laboratory personnel have specific training in handling pathogenic and potentially lethal agents, and are supervised by competent scientists who are experienced in working with these agents. All procedures involving the manipulation of infectious materials are conducted within biological safety cabinets, specially designed hoods, or other physical containment devices, or by personnel wearing appropriate personal protective clothing and equipment. The laboratory usually has special engineering and design features, such as restricted access, double-door entrances, and sealed penetrations. BSL 3 laboratories are sometimes called warm zones.
BSL 4 includes the most lethal and exotic agents that there are no cures or vaccines for, such as Ebola, Lassa, Argentinian hemorrhagic virus, and smallpox (smallpox for its extreme virulence, despite its vaccine availability). When dealing with biological hazards at this level the use of a positive pressure personnel suit, with a segregated air supply, is mandatory. The entrance and exit of a level four biolab will contain multiple showers, a vacuum room, an ultraviolet light room, and other safety precautions designed to destroy all traces of the biohazard. Multiple airlocks are employed and are electronically secured to prevent both doors opening at the same time. All air and water service going to and coming from a biosafety level 4 (or P4) lab will undergo similar decontamination procedures to eliminate the possibility of an accidental release. Agents with a close or identical antigenic relationship to biosafety level 4 agents are handled at this level until sufficient data is obtained either to confirm continued work at this level, or to work with them at a lower level.
Members of the laboratory staff have specific and thorough training in handling extremely hazardous infectious agents and they understand the primary and secondary containment functions of the standard and special practices, the containment equipment, and the laboratory design characteristics. They are supervised by qualified scientists who are trained and experienced in working with these agents. Access to the laboratory is strictly controlled by the laboratory director.
The facility is either in a separate building or in a controlled area within a building, which is completely isolated from all other areas of the building. A specific facility operations manual is prepared or adopted. Building protocols for preventing contamination often use negatively pressurized facilities, which, even if compromised, would severely inhibit an outbreak of aerosol pathogens.
BSL 4 labs are hot zones.