Biological safety cabinets are critical protective equipment in clinical testing and biological product manufacturing. They play a central role in safeguarding operators, experimental samples, and the surrounding environment.

The core function of biosafety is to establish a directed, controlled air barrier (typically an inward airflow) and purify both intake and exhaust air through HEPA/ULPA filtration.

Class II Biological Safety Cabinets (Most Commonly Used): Simultaneously protect personnel, the environment, and samples. Based on exhaust methods and structural ratios, they are subdivided into subtypes such as A1, A2, B1, and B2. Among these, the Class II A2 model is the absolute mainstream choice for clinical settings and most production scenarios.

Class III Biosafety Cabinet: Fully enclosed, glove box-style, designed for handling pathogens of the highest risk level (e.g., Ebola virus).

Clinical testing laboratories (particularly those specializing in microbiology, molecular diagnostics, and immunology) are the settings where biosafety cabinets are most frequently used, primarily for processing patient specimens that may contain pathogens.

1. Primary Application Scenarios:

Microbial Culture and Identification: Handling bacterial, fungal, and mycobacterial cultures to perform smears, subcultures, and antimicrobial susceptibility testing. This is a critical step in preventing laboratory-acquired infections.

Molecular Biology Testing:

Nucleic Acid Extraction: Handling samples containing potential pathogens such as sputum, blood, or tissue. Opening containers may generate aerosols.

PCR Reaction Setup: Conducted in a clean area to prevent environmental DNA/RNA contamination of samples causing false positives (protect samples).

Serology and Immunology Testing: Handling serum or plasma samples potentially containing bloodborne pathogens (e.g., HBV, HCV, HIV) during aliquoting, dilution, and related procedures.

Tuberculosis Laboratory: Processing high-risk samples like sputum for smear preparation and culture must be performed within a biosafety cabinet.

Virology Culture: Handling viral cell cultures.

2. Core Role in Clinical Testing:

Personnel Protection: Prevents inhalation of pathogen-containing aerosols by operators. Operations such as mixing, centrifugation, and pipetting may generate invisible aerosols.

Sample Protection: Provides a clean working area through vertical laminar flow (Class II) to prevent sample contamination from ambient microorganisms or cross-samples, ensuring test result accuracy.

Environmental Protection: Exhaust air undergoes HEPA filtration to ensure clean emissions, safeguarding both the laboratory and external environments.

In clinical testing, biological safety cabinets serve as a lifeline for protecting healthcare workers and ensuring testing quality. They embody the ultimate pursuit of "safety" and "quality" in modern biotechnology and represent indispensable infrastructure in the biomedical field.