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There are two Containment Level 3 (CL3) laboratories in the NDMRB, located on the first floor, within the Viral Immunology Unit. Access to these suites is strictly restricted to those staff who have been appropriately trained and given authorisation to work in these areas by those responsible. Work with some pathogens also requires personnel to be examined initially by the Occupational Health Service in order to be declared 'Fit to Work'.

For access please contact the CL3 supervisor

All users must be familiar with the Code of Practice and must have fcompleted a pathogen registration form.

Access control

Access to these suites is strictly controlled and only given to those who have been adequately trained and authorised by the CL3 Safety Officer. Both suites are accessed via a shared lobby. 

A proximity card and access code are required for access to the lobby and suite doors. The doors are controlled by an interlock system which prevents more than one door being opened before another has closed. This is a feature intended to preserve the negative pressure in these laboratories.

Control panels

cl3-entrance-jpg.jfifThere are control panels situated outside of the CL3 laboratories to the left of the lobby door indicating whether the extract fans connected to the Biological Safety Cabinets (BSC) are operational.

Gauges providing readings for the air pressure between the CL3 laboratory and the external corridor, between the CL3 laboratories and the lobby and between the lobby and the external corridor are also situated outside of the CL3 laboratories, to the right of the lobby door.


It is essential that the CL3 laboratories are maintained under negative pressure to the rest of the laboratory areas at all times.  

In the event of airflow failure, the Air Handling Unit (AHU) will automatically shut down in order to prevent any risk of positive pressurisation or air being transferred between the two laboratories. The failure of the air extract system will be clearly indicated by an alarm in each of the laboratories. Work in the laboratories must be stopped and not reinstated until assurances have been given by the relevant Estates Department staff that the problem has been resolved.

Integrity tests and fumigation

CL3 laboratories must be completely sealed to enable them to be fumigated with formaldehyde in the event of a spillage of infectious material. The laboratory manager inspect the integrity of the CL3 laboratories annually, or after structural work has taken place, to ensure that they are sealed for fumigation in the event of an incident.


All waste produced in these laboratories must be inactivated by disinfection or steam sterilization. Infectious waste that has been autoclaved is then transferred to yellow clinical waste bags in the lobby area, sealed with the appropriate plastic tie, then placed in one of the yellow bins in the corridor for collection. Chemical and other waste is dealt with by request to the Laboratory Management. It is essential that the printouts for each autoclave cycle are kept in chronological order should they be required for inspection, either internally or by the HSE.


Laboratory Management carry out monthly checks on all of the CL3 laboratories in order to ensure that they are functioning correctly, noting any faults that require action. 


The BSCs and autoclaves are serviced every six months to ensure that they are functioning correctly and are compliant with the relevant regulations. BSCs are checked to ensure that the airflows are correct and the pre-filters and HEPA filters are changed as required.

The autoclaves are serviced every six months, calibrated every twelve months and re-validated every two years (more frequently if there is any change of use). In order to comply with the 'pressurised steam vessels' legislation.

Permit to work

Contractors who come to service or repair equipment in the CL3 laboratories must be provided with a Permit to Work form, which must be signed by a senior member of the CL3 staff or a Laboratory Manager before work commences. Laboratory Management keeps record of these permits. It is essential that contractors are made fully aware of the hazards in the area where they are working and should ideally only be allowed in during down-time and supervised at all times if unfamiliar with the laboratories. They must be informed of the procedure in the event of the fire alarm sounding.

Fire safety procedure

In the event of the fire alarm sounding all personnel working in the CL3 laboratories must make what they are doing safe then make their way out of the building and to the assembly point. There are two fire escape routes from the building:

  • One fire exit route is along the primary laboratory corridor to the first floor atrium, taking the stairs down to reception and walking through the opened turnstile to exit the building. The assembly point is situated behind the triangular building opposite the NDMRB.
  • The other fire exit route is via the back staircase, down the stairs to the ground floor area, exit via the push-bar fire exit door, walking around the building on the pavement. The assembly point is situated behind the triangular building opposite the NDMRB.

Additional safety measures

CCTV cameras are located in the corridor outside the lobby door.

N.B. The Laboratory Management must be notified immediately of any faults that are observed in any of the building's CL3 laboratories.