Biosafety Levels

About Biosafety Levels

Biosafety levels BSL are a set of containment precautions designed to protect laboratory workers and the environment from infectious agents. BSL 1 is for agents not known to cause disease in healthy adults, such as non pathogenic E coli. BSL 2 is for agents causing moderate hazards, such as Staphylococcus aureus and HIV. BSL 3 is for agents that can cause serious or lethal disease through inhalation, including Mycobacterium tuberculosis, SARS CoV, and yellow fever virus. BSL 3 laboratories have negative pressure, directional airflow, and HEPA filtration. BSL 4 is for dangerous agents for which treatments or vaccines are limited or unavailable, such as Ebola, Marburg, and smallpox viruses. BSL 4 laboratories use positive pressure suits with dedicated air supply. Surveys in the early 2020s counted roughly 60 to 70 BSL 4 laboratories worldwide. The number of BSL 4 labs has increased significantly since 9 11, driven by biodefense funding. This expansion has raised concerns about safety and oversight.