Biosafety: what really determines the containment level of a laboratory

01The misconception: “this is a BSL-2 laboratory”

Room schedules often simply say “BSL-2” or “BSL-3” – as if the level were a property of the room. In fact, it is the result of an assessment. Internationally, the term used is biosafety levels; in Switzerland, the Containment Ordinance (ContainO) regulates the subject with three separate axes, which are often confused in everyday practice.

02Three axes instead of one number

1. Group 1–4 – the hazard of the organism, for example according to pathogenicity, route of transmission and treatability. The FOEN maintains public lists of organisms for this purpose.
2. Class 1–4 – the risk of the specific activity: organism, nature and scale of the work, environmental conditions.
3. Safety level 1–4 – the structural, technical and organisational measures under Annex 4 ContainO.

Group and class usually coincide. However, they can diverge if the activity significantly increases or reduces the risk – large culture volumes are to be assessed differently from a single diagnostic sample. The class also determines the procedure: Class 1 and 2 activities are notified to the Federal Coordination Centre for Biotechnology, while Class 3 and 4 activities require authorisation. Establishments with Class 3 or 4 activities are also, in principle, subject to the Major Accidents Ordinance (MAO).

03Where the technology jumps

Annex 4 of the ContainO lists the measures for each level, separately for production, laboratory, greenhouse and animal facilities. For laboratory activities, a clear pattern emerges: level 2 mainly requires restricted access, a microbiological safety cabinet and sound work organisation – but no negative room pressure. Only from level 3 does the ordinance provide for negative pressure relative to the surroundings, HEPA-filtered exhaust air, an airlock and an autoclave in the work area. Level 4 adds, among other things, HEPA-filtered supply air and a pass-through autoclave.

Many level 3 measures are marked in the ordinance as required, but modifiable with authorisation. This creates scope – but only with a substantiated risk assessment and early consultation with the competent federal office.

04The conflict with product protection

Biosafety aims to keep the organism in the room, hence negative pressure. Aseptic manufacturing aims to protect the product, hence positive pressure. Where both apply, for example in cell and gene therapy, the objectives are in conflict. Solutions are airlocks as decoupling pressure buffers, separate zones or – most effectively – closed systems and isolators, which decouple product protection from room pressure. The EU GMP Guide also explicitly provides for adapted pressure concepts for pathogenic materials.

05What this means for your project

• Have the risk assessment for each activity prepared before the room schedule – with group, class and level for each room.
• Clarify early whether a notification or authorisation procedure and major accident prevention are required; this determines the schedule.
• Define the pressure direction of each zone before the ventilation is designed – especially where GMP or radiological protection overlap, where several sets of regulations and supervisory authorities run in parallel.
• For animal facilities, consider additional escape routes such as bedding, carcasses and waste water.

Takeaway

It is not “biological” that determines the containment level, but the organism together with the activity – and the pressure direction follows the protection objective, not habit.

SEDC AG · Article from our internal training series “Technik Praxis”, abridged for clients and users.