Microbiological safety cabinets (MSW) in genetic engineering facilities – Class 1 safety cabinets

During genetic engineering work that generates aerosols, it must be ensured from safety level 2 onwards that these do not enter the work area (GenTSV, Annex 2, A. II. a. No. 6). The core technical measure here is the microbiological safety cabinet (MSW). However, even when working with S1 organisms, e.g., during cloning work in E. coli K12 strains, the use of safety cabinets is recommended to prevent the spread of contamination. The basic principle of all MSW is that a directed airflow is generated within a shielded work area, protecting the experimenting personnel and the room air from aerosol-mediated contamination. In all safety cabinets, the air escaping from the work area is therefore passed through one or more high-efficiency particulate absorbing (HEPA) filters. Particular attention should be paid to the placement of the MSW in the laboratory. This is because air movement in the room, at least in "semi-open" Class 1 and 2 MWs, may interfere with the airflow directed toward the HEPA filter within the workbench. In the event of interference, microorganisms could disrupt the airflow, causing biological agents to escape from the MW. Therefore, MWs should not be placed near doors, windows, walkways, or the inlet and outlet openings of laboratory ventilation systems.