For each biosafety level,  a combination of laboratory practices and techniques, safety equipment, and laboratory facilities is required to protect the worker, the population and the environment from exposure to biohazardous materials (refer to BMBL for details). 

Biosafety level 1 (BSL-1): is the basic level of protection and is appropriate for agents that are not known to cause disease in normal, healthy humans.

Biosafety level 2 (BSL-2): is appropriate for handling moderate-risk agents that cause human disease of varying severity by ingestion or through percutaneous or mucous membrane exposure. All human and primate-derived materials must be treated at BSL-2 or above, because they are at a higher risk for bloodborne pathogens.

Biosafety level 3 (BSL-3): is appropriate for agents with a known potential for aerosol transmission, for agents that may cause serious and potentially lethal infections and that are indigenous or exotic in origin

Biosafety level 4 (BSL-4): is appropriate for exotic agents that pose a high individual risk of life-threatening disease by infectious aerosols and for which no treatment is available.

Biosafety Level is assigned based on the RISK GROUPS of the materials to be utilized in the project and a risk assessment of the manipulations involved.

• CULTURED CELL LINES - refer to Risk Group information
• BACTERIA, FUNGI, VIRUSES - refer to NIH GUIDELINES
• RECOMBINANT DNA (rDNA) - BSL1 (unless toxic or virulent; refer to NIH GUIDELINES )
• HUMAN OR NON-HUMAN PRIMATE DERIVED MATERIALS (Including cell lines) - BSL2