Biosafety cabinet use

Principle

• A biological safety cabinet (BSC) uses inward airflow and HEPA-filtered air to contain infectious aerosols.
• HEPA filters remove at least 99.97% of particles of 0.3 µm.
• Class I: protects the user and environment but not the product.
• Class II (types A1, A2, B1, B2): protects the user, the product (downward sterile airflow) and the environment; most common in clinical labs.
• Class III: fully enclosed, gas-tight glove box for the highest-risk agents (BSL-4).

Reagents and equipment

• Certified Class II BSC, suitable disinfectant (e.g. 70% alcohol or fresh diluted bleach followed by water or alcohol rinse), disposable loops or micro-incinerator, discard containers.

Procedure

• Check the certification date and airflow alarm/indicator; switch on and let it run a few minutes (about 3–5 minutes, per manufacturer) to purge.
• Disinfect the work surface and load only needed items, keeping front and rear grilles clear.
• Work at least about 10 cm (4 inches) inside the front opening, moving from clean to dirty areas.
• Move arms slowly, straight in and out; limit people walking behind you.
• Keep the sash at the correct working height.
• After work, close containers, disinfect items and surfaces, and let the cabinet run a few minutes before switching off.

Quality control and pitfalls

• Certify on installation, at least annually, and after moving or filter change (e.g. per NSF/ANSI 49).
• Open flames disrupt airflow and can damage the HEPA filter; use micro-incinerators or disposable loops.
• UV lamps are not a substitute for chemical disinfection and harm skin and eyes.
• Blocking grilles, crowding the work area or rapid movements break containment.
• A BSC is not a chemical fume hood; most Class II cabinets recirculate air and are unsuitable for volatile toxic chemicals.
• A horizontal laminar flow clean bench protects only the product and must not be used for infectious material.

Clinical use

• Processing of TB specimens, mold cultures, suspected high-risk pathogens and any procedure that can produce aerosols.