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Chemical, Biological, Radiological and Nuclear (CBRN) Threats

‘CBRN’ is the abbreviation commonly used to describe the malicious use of Chemical, Biological, Radiological and Nuclear materials or weapons with the intention to cause significant harm or disruption. The hazard posed by these materials varies: 

  • Chemical

    Poisoning or injury caused by chemical substances, including traditional (military) chemical warfare agents, harmful industrial or household chemicals.

  • Biological

    Illnesses caused by the deliberate release of dangerous bacteria or viruses or by biological toxins (e.g. ricin, found in castor oil beans).

  • Radiological

    Illness caused by exposure to harmful radioactive materials.

  • Nuclear

    Life-threatening health effects caused by exposure to harmful radiation, thermal or blast effects arising from a nuclear detonation.

Within the wider definition of CBRN, the  term ‘White Powder(s)’ is also often used in a mail context to describe the potential presence of a noxious substance (or hoax material) in a letter or parcel. More information on White Powders, including definitions and mitigation measures is available from the Screening Mail and Courier Deliveries page and also from PAS 97:2015 which is available from the BSi website.  


CBRN Mitigation

Good general physical and personnel security measures will contribute towards resilience against CBRN incidents. Remember to apply appropriate personnel security standards to contractors and visitors, especially those with frequent access to your site.

Full CBRN protection can be extremely expensive to implement, however some CBRN mitigation measures that will mitigate to a certain extent the effects of a CBRN event can be put in place at relatively low cost. CPNI recommend the following first steps to increase your resilience to a CBRN attack:  

  • Review the security physical measures relevant to areas of your building that may, due to their function (entrances, etc), be at increased risk of attack.
  • Review the design and physical security of your air-handling systems, such as access to intakes and outlets.
  • Improve air filters or upgrade your air-handling systems, as necessary.
  • Restrict access to water tanks and other key utilities.
  • Review the security of your food and drink supply chains.
  • Consider whether you need to make special arrangements for mail or parcels, e.g. a separate post room, possibly with dedicated air-handling, or even a specialist off-site facility.

CBRN Response

A basic awareness of CBRN threat and hazards, combined with general protective security measures (e.g. screening visitors, CCTV monitoring of perimeter and entrance areas, being alert to suspicious letters and packages) should offer a good level of resilience. A range of commercial CBRN detection technology is available, though the maturity of some of these technologies, and their suitability for use in a security context, requires that specialist advice should be sought prior to any procurement decisions.

The actions that are taken by building managers and security staff can, in the immediate moments following a CBRN attack, have a very significant effect on limiting the effects of such an incident. Pre-planned actions focusing on limiting the effects of such an attack will help to ensure that building occupants are protected as far as is reasonably practicable.

In certain areas it is possible to provide a list of 'immediate actions' which staff/security staff should follow in order to mitigate the effects of a CBRN attack and to summon the relevant support from the Emergency Services. Examples of actions which could be relevant include:

  • Dialling 999 with a pre-prepared message to convey the nature and location of the incident;
  • Plan for the shutdown of systems that may contribute to the movement of airborne hazards (e.g. HVAC systems, etc);
  • Ensure that doors can be closed quickly if required;
  • If your external windows are not permanently sealed shut, develop plans for closing them in response to a warning or incident;
  • Examine the feasibility of emergency shutdown of air-handling systems and ensure that any such plans are well rehearsed;
  • Where a hazard can be isolated by leaving the immediate area, do so as quickly as possible, closing doors and windows as you go;
  • Move those directly affected by an incident to a safe location as close as possible to the scene of the incident, so as to minimise spread of contamination;
  • Separate those directly affected by an incident from those not involved so as to minimise the risk of inadvertent cross-contamination;
  • Ask people not to wander off - though you cannot contain them against their will;
  • You do not need to make any special arrangements beyond normal first aid provision. The emergency services will take responsibility for treatment of casualties.

The exact composition of the 'immediate actions' will vary from building to building and in some circumstances an action which may be appropriate for one building may be inappropriate for another. CPNI strongly recommends that users get to know their building (and procedures) in preparation for developing their list of immediate actions. 

If you have a designated protected space this may also be suitable as a CBRN shelter, but seek specialist advice before you make plans to use it in this way.


Business Continuity

Business interruption following a CBRN incident could potentially compromise an organisation’s ability to sustain normal operations. The severity of this disruption will depend on the nature of the incident (principally the CBRN agent employed), and may ultimately be influenced by how long it takes to decontaminate the area affected.

CBRN decontamination may be costly, take a significant period of time or in extremis could be impossible. The UK government has published Strategic guidance relevant to decontamination of buildings.