BSL-2 and BSL-3 in a container: is it possible?

Work with hazardous biological agents requires the highest safety precautions. Laboratories at biosafety levels BSL-2 and BSL-3 must meet strict structural and technical requirements to protect staff and the environment. For a long time this was regarded as the domain of involved solid construction. Yet modern container laboratories prove: the highest safety is also possible in modular construction.

Fundamentals of biological biosafety levels

Biological biosafety levels — known internationally as Biosafety Levels (BSL) — classify laboratories according to the hazard of the organisms handled there. In Germany these are governed by the Biological Agents Ordinance (BioStoffV) and the Technical Rules for Biological Agents (TRBA).

While BSL-1 and BSL-2 laboratories are comparatively common, BSL-3 laboratories present a particular challenge because of their complex structural requirements. BSL-4 laboratories — the highest biosafety level for work with pathogens such as Ebola or Marburg virus — have not to date been realised as a container module because of their extreme requirements.

BSL-2 in container format: proven and reliable

Laboratories at biosafety level 2 are intended for work with organisms that can cause disease in healthy adults, but for which effective treatment options exist. Typical applications are routine microbiological testing, work with cell cultures or diagnostic laboratories.

The structural requirements for BSL-2 laboratories include, among others:

These requirements can be met without difficulty in a well-planned container module. Our BSL-2 containers are equipped with washable wall surfaces, integrated hand-wash basins and connections for biosafety cabinets. Technical planning takes all details into account from the start.

BSL-3: the premier class in container construction

Laboratories at biosafety level 3 serve work with organisms that can cause serious disease and for which effective therapies or prophylaxes are not always available. These include, for example, Mycobacterium tuberculosis, West Nile virus or certain influenza strains. The structural requirements are correspondingly strict.

The negative-pressure zone: heart of safety

The most important safety feature of a BSL-3 laboratory is controlled negative-pressure holding. Air pressure in the laboratory area sits about 30 to 50 pascals below ambient pressure. As a result, air flows inwards from outside at every opening — never the reverse. Potentially contaminated air cannot therefore reach the surroundings.

In a container laboratory this negative-pressure zone is realised by a gas-tight cabin construction. All penetrations — for electrics, media, ventilation — are executed with specialist sealing systems. The ventilation plant is designed redundantly and fitted with automatic emergency shutdown in the event of faults.

The airlock concept

Access to the BSL-3 area is via a multi-stage airlock system. Typically this consists of a black-and-white separation with changing area, a shower passage and the actual personnel airlock. The airlocks are fitted with interlocks so that both doors can never be opened at the same time.

In a compact container laboratory this airlock concept must be implemented cleverly. Optimised layouts make it possible to accommodate all required functions in a tight space. Depending on requirements, the airlocks can be housed in a separate upstream container or in the same module.

Technical systems for maximum safety

Ventilation and filter systems

The ventilation plant of a BSL-3 container laboratory is built redundantly. Two independent extract fans ensure continuous operation even if one system fails. Extract air is passed through HEPA filters of class H14, which retain at least 99.995 per cent of all particles with a size of 0.1 to 0.3 micrometres.

Supply air is also filtered to prevent the introduction of contamination. Airflow is designed so that clean air enters in the entrance area and is extracted towards the contamination source — a directed airflow that minimises the spread of aerosols.

Decontamination and waste disposal

All materials leaving the BSL-3 area must be decontaminated. Pass-through autoclaves are typically used for this, forming the transition between the contaminated and clean areas. Liquid waste is inactivated chemically or thermally before discharge.

For room gassing — for example after an incident or before maintenance work — connections for formaldehyde evaporators or hydrogen peroxide generators must be provided. These enable complete decontamination of the entire laboratory area.

Monitoring and documentation

A BSL-3 laboratory requires extensive monitoring and documentation systems. Pressure sensors continuously monitor negative-pressure holding and trigger an alarm if there are deviations. Door contacts log every access. Video surveillance documents activities in the laboratory.

Advantages of the container concept for high-containment laboratories

Realising BSL-2 and BSL-3 laboratories in container form offers specific advantages that go beyond the general merits of modular construction:

From concept to approval

Realisation of a BSL-2 or BSL-3 container laboratory follows a structured process. At the beginning sits the needs analysis: which organisms are to be processed? Which working procedures are planned? How many people will work in the laboratory? On the basis of this information we develop the concept.

In parallel, coordination with the permitting authorities begins. For BSL-2 laboratories a notification to the competent authority is generally sufficient. BSL-3 laboratories require a permit, the granting of which depends on a review of the structural and organisational prerequisites. Our consulting experts accompany you through this process.