This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Investigating major explosions and fires caused by explosives


Version No:
OG Status:
Fully Open
Author Section:
Target Audience:
All HID & FOD Inspectors


1. This SPC is primarily intended for Inspectors from HID SI2 (Explosives), although it is relevant to inspectors from FOD and HID CI who may provide the initial response to explosives incidents.  It should be read in conjunction with the relevant FOD divisional Major Incident Response Plan (MIRP), which gives practical guidance to inspectors responding to events that are, or may escalate into, major incidents.  Fires and explosions caused by explosives can present unusual difficulties for inspectors and in some cases the MIRP procedures may be challenging to apply.  This SPC complements the MIRP by providing additional help on specific issues that inspectors investigating explosives incidents may come across.


2. Each FOD division has a MIRP.  HSE's procedures require that it is applied when an event occurs that requires HSE’s attention and meets the following criteria:

3. All FOD and HID operational staff are expected to follow their divisional MIRP when responding to an incident that meets the above criteria.  Fires and explosions arising from events involving explosives may fall within the scope of the MIRP.  All SI2 inspectors should have access to a copy of the FOD divisional MIRP(s) for the area(s) they operate across.

4. This SPC augments the MIRP by providing inspectors with specific help regarding issues that they may not have come across before. This reflects the unusual nature of explosives incidents, for example:

Demarcation of responsibility between HID SI2 and other regulators

5. HID SI2 is responsible for enforcement relating to the activities of explosives site dutyholders.  These sites are subject to licensing and HID SI2 assumes all responsibility for enforcement at such sites.

6. Some sites contain specific areas at which explosives related activities take place, which are subject to licensing. The remainder of the site may be enforced by FOD, ONR or another team in HID. For incidents at such sites decisions should be made early on as to specific investigation responsibilities.

7. HID SI2 sites are located across the country and the unit’s inspectors are based in Bootle. Therefore, liaison with colleagues in FOD and HID who are located closer to site may be necessary, as they may be best placed for any immediate site attendance.

Interface with the MIRP

8. The MIRP contains common procedural information along with division-specific contact details, e.g. for HSE inspectors (both FOD and HID), council offices and emergency services within that division. It defines a number of key roles within HSE's major incident response, e.g. decision maker, incident controller, incident inspector. It also contains guides, checklists and flowcharts which are designed to support the people who take on those roles during a major incident.  In Scotland, the MIRP contains an additional appendix reflecting the different Work Related Deaths Protocol procedures required.  The MIRP is regularly tested, reviewed and if necessary revised to ensure it remains fit-for-purpose.

9. It is recognised that the teams within SI2 inspect over large geographical areas which may cover a number of FOD divisions. Rather than holding a copy of the MIRP for every division, SI2 inspectors should have a personal hard copy of the MIRP for the division within which they are based.  In the event of an incident occurring within normal work hours, further details to those included in the inspector's copy of the MIRP can be provided by colleagues. All MIRPs contain a list of out-of-hours numbers which may be useful to inspectors in any region.

10. The MIRP is maintained by administrative staff on behalf of the FOD Head of Division and updates are periodically sent to holders of hard copies.  Any SI2 inspector who does not hold a MIRP should ask SI2 unit admin, on the inspector’s behalf, to contact FOD administrators at the relevant office and request one.  SI2 unit admin will ensure that MIRPs are updated when appropriate. Inspectors should ensure that their MIRP is stored in a convenient location so it can be readily accessed in the event of an incident.  An additional list of emergency contact details for all operational staff and managers in SI2 is maintained by Unit admin at Bootle. Inspectors should keep a hard copy of this list in their MIRP. Other useful reference material for inspectors attending explosives incidents is listed in Appendix 1.

Relevant legislation

11. At explosives licensed sites the following Regulations may apply:
The Manufacture and Storage of Explosives Regulations 2005
The Dangerous Substances in Harbour Areas Regulations 1987.

12. At some sites, where the quantities of explosives stored or handled exceed certain qualifying thresholds, the following Regulations may also apply:
The Control of Major Accident Hazards Regulations 1999 (as amended)
SI2 also regulates one acetylene compressing site (which is subject to a site approval and specific acetylene legislation, as well as COMAH) and a large number of ammonium nitrate storage sites (which may be subject to COMAH).

For incidents occurring during road transport of explosives, acetylene or ammonium nitrate the relevant regulations are:

Notification of incident and initial arrangements

13. During office hours, SI2 may be alerted to incidents either via other directorates or direct from the dutyholder. If a call is taken alerting HSE to an incident that may meet the major incident criteria, the SI2 band 2 inspector (who will become the Investigation Manager) for the specific region should be told immediately (or, in their absence, a Band 3 for the region or another Band 2).

14. The notified inspector should immediately assess the potential for the incident to meet the major incident criteria and, if this is the case, should notify HoU. If the incident warrants application of the MIRP,

15. If the incident occurs out of normal working hours, the HSE Duty Officer will contact the band 2 specialist inspector, who will then determine whether immediate response is required and if so, follow the procedure as above (14), (which may additionally require out of hours access to Redgrave Court).

Before attending site

16. If FOD or other HID inspectors are required for immediate response, the HID SI2 Investigation Manager (Band 2) should make immediate contact to ensure that everyone has a clear understanding of who is expected on site and what their roles will be, until the HID SI2 inspector(s) arrives at the site. 

17. It should be on the basis of a clear understanding regarding role, which may be:

18. The Investigation Manager will ensure that up to date information as to the potential hazards at site (either provided by liaison with site or from site files), information as to the incident and situation, and information on precautions required according to the SI2 risk assessment, is used to inform decisions on staff health and safety.

19. The Investigation Team members will take appropriate PPE and act on any specific information and instructions on the risks they may encounter.

20. The Incident Response Pack (IRP) should be collected from the local area office en route to the scene, if possible.  The IRP contains necessary equipment to commence an investigation, e.g. enforcement notices and essential personal protective equipment.

21. For a major incident, a minimum of two inspectors should attend the scene initially.  Inspectors should contact the site, or the emergency services, before attending to advise those in control who to expect and when, and to ask them to ensure that the scene is not disturbed before HSE personnel arrive. 

22. If initial information from the scene suggests a strong possibility that certain specialists will be needed, e.g. from HSL or specialist groups (SGs), it is advisable to contact them before attending site.  If they are aware of the incident at an early stage they will be better able to respond quickly should their presence on site be needed.

Arriving on site

23. Inspectors should introduce themselves to the senior fire and police personnel on site and explain HSE's role in investigating the incident.  As Category 1 responders, the emergency services will most likely have control of the scene. HSE inspectors may have a role in offering authoritative advice to persons at the scene if requested to do so.
It is useful to have a meeting to establish the current position and confirm whether there have been any casualties.  Where fatal injury has occurred or the condition of casualties is such that fatality is foreseeable, agreement will need to be reached with the police regarding whether they retain control of the scene or hand it over to HSE once it has been made safe. Other key actions and considerations for inspectors during the early stages of the investigation are listed in Appendix 2.

Controlling major incidents and liaison with the emergency services

24. HSE is a Category 2 responder under the Civil Contingencies Act 2004 and plays a supporting role in planning for and responding to emergencies.  Inspectors should resist any pressure to become involved in the incident command and control mechanism established by Category 1 responders such as the emergency services and LAs.  In the case of explosives incidents, HSE inspectors can assist Category 1 responders by acting as a source of authoritative advice to decision makers at the scene, e.g. regarding whether evacuation or other precautions are necessary to protect the public. 

25. Inspectors should be prepared to give advice to the emergency services on health and safety issues within HSE's remit.  However the MIRP makes it clear that HSE staff should only intervene in their enforcement capacity in circumstances of extreme risk to the emergency services or others.

26. Where inspectors are going to be working at the scene of an incident for more than a day, they should meet before work starts each morning for an opening briefing and hold a debrief meeting each evening.  This is to ensure that all HSE personnel are kept fully informed regarding developments on site and have the opportunity to flag up and discuss issues that arise as the investigation progresses.

Action in the event of a fatality - the role of the police and manslaughter considerations

27. If death has occurred or is foreseeable, the police will have primacy for the investigation and control of the scene until they take a positive decision that no manslaughter offence has taken place.  HSE will assist with the manslaughter investigation whilst also investigating possible offences under the Health and Safety at Work etc Act 1974 (HSWA).  The exact working arrangements need to be agreed with the officer in charge in each case.  Further guidance is given in OC 165/10 and in the Work Related Deaths Protocol (WRDP).

Site accommodation

28. Inspectors' powers enable them to require that accommodation is made available to them for use during an investigation. However, this can be a problem with explosives incidents or at remote locations.  HSE can arrange for a Mobile Major Incident Room (MMIR) to be brought to site or can lease temporary office accommodation locally.  Further details and procedures for requesting the MMIR or temporary office accommodation are in the MIRP (Appendix 16).  Inspectors will need to consider the following in relation to the MMIR:

Entry into damaged buildings and return to evacuated properties

29. Inspectors may face pressure from various parties to allow entry to damaged/evacuated buildings to enable investigations or remedial works to proceed after the emergency services have completed their work.  The overriding priority is to ensure that no-one is put at further risk.  It is therefore critical that inspectors do not act without first taking the appropriate specialist advice and do not feel that they must rush into making a decision.  Typical issues include:

Inspectors' health and safety

30. HSE has a corporate policy entitled 'Health, safety and welfare of staff involved in cross-directorate major investigations' and a complementary 'Checklist for site risk assessment'.   This states that an initial risk assessment should be conducted and all precautions identified by the risk assessment should be in place before work on site begins.  Inspectors should be familiar with the contents of these documents and it is recommended that they keep hard copies with their MIRP for reference.  If in doubt regarding any personal health and safety issue, inspectors should always seek advice from their line management and/or discipline specialists.
31. The guiding personal health and safety principles that inspectors should observe on site are:

32. A particular hazard which may not be obvious is the presence of asbestos at the scene.  Where there is reason to suspect the presence of asbestos, inspectors should not enter the site.  If in doubt, inspectors should seek specialist advice from Specialist Occupational Hygienists or FOD Construction Division Inspectors.

33. Inspectors could find themselves in emotionally challenging situations and may feel obliged to work long hours in the course of the investigation.  It can be helpful to talk about these issues at daily briefing/debrief meetings.  HSE staff have access to a free counselling and support service provided by Right Corecare and a counsellor can attend site to talk to staff on request.  Where booking into local accommodation would reduce travel time and stress, this can be arranged via Expotel (contact details are provided in the MIRP).

Night working

34. On occasion it may be necessary to work through the night. The person in charge of the response may make such a request. Such requests should be treated sympathetically as there will be pressure to re-open roads, allow the public back into their homes, etc. This work may require the assistance of specialist support and/or contractors. There are two considerations to be given to night working:

  1. can the work be done safely at night? and
  2. are staff from HSE and technical staff from HSL/SG content to remain on site to supervise the activities of the contractor(s) and ensure that no evidence is disturbed?

If the answer to both of these questions is yes, then night working may be allowed and should be recorded in the key decision log.  The police may be able to help by maintaining a cordon overnight. LAs also have a role in security of the site perimeter and may be able to assist.

How the investigation is carried out - the role of Specialist Groups (SGs), HSL, technical contractors

35. SGs- It may be necessary to request input from specialist inspectors, (eg C&I, process safety, etc). The route for requesting SG support is through the relevant SG Band 2.

36. HSL - clear terms of reference should be established and recorded between HSE and HSL to ensure that all appropriate lines of enquiry are investigated.  HSL can provide a range of services including fire and explosion expertise, metallurgy, photography (video/still/laser scanning) and creation of plans or drawings.  Inspectors should remember that HSL staff do not have the same level of legal/investigative training as inspectors and will require supervision to ensure compliance with the Criminal Procedures and Investigation Act 1996 (CPIA) and preservation of the chain of evidence. 

37. Technical contractors - In some circumstances, independent investigations are conducted either by the company having the incident or by technical contractors appointed by the company. HSE are likely to be interested in their findings so a positive dialogue should be established with them, although Inspectors must make it clear that the contractor should only proceed with their investigation after formal agreement with HSE and a record being made in the key decision log.

38. Other parties may also have an interest in technical aspects of the investigation, e.g. insurer's representatives.  It is reasonable for them to do their job, e.g. to take photographs and measurements, but inspectors should make it clear that they are not part of the HSE investigation and that their interests are secondary to it.  Other parties should not be allowed to direct or otherwise interfere with the HSE investigation; have access to confidential documents and/or discussions; or carry out any activities which may compromise evidence.  Inspectors should ensure that all parties are fully aware of these constraints and understand that they must not do anything which could have implications for the investigation without first gaining formal authorisation from HSE.  Where inspectors authorise other parties to undertake certain activities, they will need to be consistent in the event that further requests of the same nature are made.  They should therefore be mindful of any precedent they may set and its logistical implications.

Investigation priorities

39. Appendix 3 contains an evidence checklist which covers the key evidential issues facing inspectors investigating explosives incidents.  

Handling the media and communications

40. Explosions and fires caused by explosives are newsworthy events, particularly if there are serious injuries. Investigating inspectors are likely to encounter personnel from the media.  HSE has a policy of openness and transparency in its dealings with the media.  Press Office should be contacted at an early stage because they can deal with many media enquiries and in doing so take the pressure off the inspectors at the scene. The senior HSE manager involved in the investigation should normally give any press briefings. However inspectors on site may be requested to comment and should be prepared to make a brief holding statement as set out in the MIRP.

41. Although it is clearly inappropriate to offer detailed comments in some circumstances, for example where it may prejudice criminal proceedings, inspectors can respond to enquiries from the media helpfully by giving information such as:

42. HSE Secretariat need to be informed within one hour if there has been a potential major incident.  Contact with Secretariat will be via the Incident Controller, i.e. HoU (in office hours) or the duty press officer (out-of-hours), so it is important to provide a briefing to these people at an early stage of the investigation which gives them a meaningful appraisal of the situation.

43. The police and LA may all have press officers on site.  Inspectors should liaise with them as appropriate, e.g. to ensure messages concerning public safety are consistent.  They may also provide a useful conduit for delivering common messages, such as reassurance about the safety of the site and site personnel, and can help by managing local press and TV reporters where there are no GNN representatives available.

Dealing with bereaved relatives

44. In 2006, HSE introduced 'Working with victims: HSE policy statement' in response to concern that existing arrangements fell short of public expectations.  Inspectors should refer to this policy statement and the guidance set out in OM 2008/07, which sets out a timetable for making initial contact with the bereaved family, subsequent meetings and supply of information.

45. HSE will not be the only organisation wanting to talk to the bereaved family.  The police will make contact with them and may appoint a Family Liaison Officer (FLO).  Coroner's officers may also have early involvement with the family. Regardless of whether the police have primacy and/or appoint an FLO, inspectors should still follow OM 2008/07 and offer to meet with the family. The police should be kept informed of HSE's contact with the bereaved.  Where an FLO is appointed, communication arrangements should be agreed with them to ensure that there is no scope for confusion or inconsistency.

Further information

46. For further information contact the Explosives Inspectorate, HID SI2.

Appendix 1 Useful reference material for inspectors responding to major explosives incidents

It is recommended that in addition to the MIRP and this SPC, inspectors in SI2 keep hard copies of the following documents in a convenient location for taking to site in the event that they respond to a major incident:

Appendix 2 Key information/action checklist on arrival at the scene

This is not an exhaustive list but is intended to be a useful aide memoire of key actions for inspectors to take and information to gather on arrival at the scene of a major explosion or fire caused by explosives.

Appendix 3  Explosives Incident Investigation Evidence Aide Memoire

The following is a list of prompts that may assist inspectors gathering evidence during investigations into fires and explosions caused by explosives. 

Documentary evidence

Material evidence

Building Damage – Outside

Building Damage – Inside

Forensic evidence/Physical evidence preservation

Internal Inspection

Updated 2018-08-15