Recognise the need for detection, identification and monitoring (DIM) equipment

ARCHIVED – The identification of hazards is fundamental to any safe system of work at hazardous materials incidents. Typically, this is achieved either by direct observation of behaviours or by accessing information sources and specialists to get hazard information after obtaining a chemical name, UN number or Chemical Abstracts Service (CAS) number.

Where specific risks relating to substances or activities at local sites are known, fire and rescue services may provide equipment that will help responders to identify and monitor releases. Such equipment can, in some cases, determine the nature or name of the hazardous material involved. Once this is known, responders can access the usual data source and specialists to establish hazards and control measures.

In some cases, such as gas monitoring, it may be possible to monitor the spread of hazardous materials. This will help maintain safe cordon distances and determine whether intervention techniques are being effective.

In addition to monitoring equipment obtained by fire and rescue services, the government has provided a number of suites of detection identification and monitoring (DIM) equipment nationally as part of the National Resilience framework.

• Detection – recognising the presence of a hazardous or CBRN(E) material.
• Identification – determining the hazardous or CBRN(E) material that is present.
• Monitoring – quantitatively determining the presence or absence of hazardous or CBRN(E) material in a continuous or periodic process

At an incident where National Resilience detection identification and monitoring (DIM) teams are deployed the hazardous materials adviser (HMA) will act as the link between the detection identification and monitoring (DIM) team and the incident commander. At a CBRN(E) event, a CBRN(E) subject matter adviser or tactical adviser (Tac Ad), when mobilised, will be responsible for advising the incident commander on developing the tactical response plan.

An alternative or supplementary approach is to use techniques to determine the hazard directly through observation, as opposed to determining the identity and then looking up the hazards. This is given the term ‘hazard categorisation’ but is also often referred to as ‘wet chemistry’ or ‘field chemistry’ techniques.

The process is straightforward. A very small amount of the hazardous material is safely obtained as a sample. This is then subjected to a number of tests where behaviour is observed. For example, adding a small amount of water can provide a lot of information, such as whether the substance is water reactive, soluble, immiscible and floats or sinks in water. With this information, responders can predict the behaviour of the material that will help determine tactics for control.