Biohazard is defined as an infectious agent, or part thereof, presenting a real or potential risk to the well-being of man, animals and/or plants, directly through infection or indirectly through disruption of the environment. Biosafety Levels 1 through 4 were established by the Centers for Disease Control & the National Institutes of Health & are combinations of laboratory practices & techniques, safety equipment & facilities. All of these levels are appropriate for the biohazard posed by the agents used and for the laboratory activity. Each biohazard containment facility must be individually designed & constructed, so that it not only contains the hazardous material, but also is easily maintained with minimum potential exposure to maintenance & housekeeping personnel, and has flexibility for future projects. In general one should have safety equipment and facilities appropriate for work done with indigenous or exotic agents with a potential for respiratory transmission which may cause serious and potentially lethal infection. Emphasis is placed on primary & secondary barriers to protect personnel in the contagious area, the community & the environment from exposure to potentially infectious aerosols. A Class I or Class II biological safety cabinet is required for work involving these agents.