A room or suite of rooms designed to handle biological agents according to their risk groups defined in the WHO biosafety manual. Work undertaken in a laboratory at a specific level should follow procedures prescribed for that level of containment.

A process aimed at keeping biological organisms within a limited space or area. For example, if an outbreak of a cow disease is found on one farm, a biocontainment process would aim at stopping the disease from spreading to other farms.

The means by which biohazardous substances are safely sequestered. Biosafety Levels (BSL) employ a variety of means of biocontainment: BSL-0 is the containment level at which we all live; BSL-1 is the level at which most laboratory primates are contained. BSL-1 is appropriate for the containment of microorganisms, which do not cause disease in humans; workers wear some protective gear and regularly disinfect rooms and cages. BSL-2 requires more precautions: workers wear more protective gear, possibly including a face shield, sterile outer-garments, and HEPA (high efficiency particulate air) filters clean the air coming in and out of the building; BSL-2 houses nonhuman primates with infectious diseases like HIV or Hepatitis. BSL-3 and -4 house subjects infected with agents that are known to be transmitted by inhalation and are lethal to humans; physical containment requirements are very strict and include waterproof walls and ceilings (precluding the use of acoustic tiles) and controlled directional air-flow.