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BSL 4 Laboratory

BSL-1, BSL-2, BSL-3 and BSL-4 | What are they?

You may have come across this acronym before when looking at laboratories and cleanrooms but what do they actually mean?

Biosafety Level or BSL is a set of biocontainment precautions required to isolate hazardous biological agents in an enclosed manufacturing or research laboratory. These levels of protections are to safeguard laboratory personnel and the surrounding environment.

The levels of containment range from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4). These levels, from 1 to 4, are ranked according to the lethality of the agents or organisms that are being worked with in the laboratory.

Below is an explanation of each Biosafety Level, what they mean and how the protection is different.

Each level utilises the protection from the previous level and builds on this:

BSL-1: As the lowest-risk of the four Biosafety Level 1 is suitable for work with the presence of low-risk microbes and agents. These will carry little or no threat of infection to healthy adults. Operating in BSL-1 laboratories can take place on an open bench with minimal Personal Protective Equipment. Standard doors will most likely separate the lab from the rest of the facility.

An example of an organism worked with in BSL-1 would be a non-pathogenic strain of E.Coli.

BSL-2: This level covers laboratories that work with moderately hazardous agents and organisms that cause mild disease. Protection in these environments will include PPE with face shields, the use of biological safety cabinets (BSC) and personnel will be trained to handle hazardous materials. Laboratories will normally have self-closing doors and the room will most likely be under negative pressure whilst exhausted air is filtered.

Hepatitis A, B or C is an example of a virus that may be handled under BSL-2 conditions.

BSL-3: Building upon the first two levels of Biosafety, a Level 3 facility will house operations involving potentially lethal or ‘exotic’ diseases that are contracted via inhalation. Operators working with these airborne microbes will normally be immunised and wear heavier duty PPE plus respirators. All hazardous work takes place in a BSC, the lab will have double self-closing doors with locks and directional airflow to remove and filter contaminated air. Gowns and tools will also be destroyed and disposed of safely.

These laboratories will contain work being carried out on diseases like Yellow Fever or Tuberculosis.

BSL-4: As the highest level of Biological Safety, a BSL-4 laboratory consists of work with highly dangerous materials and aerosol transmitted diseases which are almost all fatal and with no available vaccines or treatments. Personnel in these laboratories must wear all PPE from previous levels as well as a full body, air supplied, positive pressure suit. Working with hazardous agents will all take place within biological safety cabinets and all materials/clothing will be decontaminated or destroyed. Personnel will be highly trained to handle the specific hazardous materials and shower after exiting.

Facilities will be isolated from any main buildings in a restricted zone, with a number of self-closing doors and airlocks. The laboratory will have its own dedicated air supply along with vacuum lines and decontamination procedures. Laboratories that require safety levels of BSL-4 are rare and often government-run or University research facilities.

BSL-4 laboratories will contain research studies on diseases like Ebola and biological weapons.

BSL 3 Nile Virus Research
BSL 3 Nile Virus Research

Biosafety Levels and Cleanrooms

BSL levels do not necessarily correlate with ISO Classifications since they are related to two different sets of regulations. BSL is sets of regulations to protect personnel and the environment from exposure whereas ISO Classification is protection of the sensitive samples and processes in the cleanroom.

The range of Biosafety Levels can require any of the ISO Classifications, subject to the sensitivity of the process to airborne particulates. However the higher levels of BSL require stricter airflow in and out of the room with a large number of air filters and air handling units. These must be combined with a higher specification of cleanroom build to ensure air tightness.

As the Biosafety Levels increase there also a requirement for regular cleaning of the laboratory/cleanroom environment. To prevent accumulation of dirt and to allow for easier cleaning regimes, a fully flush cleanroom should be specified.


Puracore has the capabilities to manufacture bespoke cleanroom systems for Biosafety Levels 1 to 4. We have already manufactured custom cleanrooms for a number of BSL facililties.

These have included projects for:

  • A high profile biological weapons research laboratory, BSL-4
  • Rare diseases research facility, BSL-3
  • Fertility labs, BSL-2
  • Production of pharmaceuticals using hazardous materials, BSL-3

Whether the facility must meet BSL 1-4 or not Puracore® can supply and deliver complete cleanroom solutions with a range of FM approved and GMP compliant components, including walls, ceilings, doors, windows and ancillaries.

Puracore® can deliver precision made components to facilitate efficient construction and outstanding cleanroom performance with a finish that is second to none.

Get in touch to find out more about our fully flush, colour matched cleanroom systems for your next project. Use our Contact Us page, call 0117 316 7925 or email