Enforcement Management Model (EMM): Application to Hazardous substances

Formerly OC 273/19


This document gives guidance to inspectors on applying the EMM to health risks from hazardous substances. General guidance on applying EMM principles to health risks, including occupational health descriptors is in Enforcement Management Model (EMM): Application to Health Risks


This guidance has been produced to help inspectors reach a proportionate enforcement decision. It contains advice on use of the EMM, in particular:

  • the application of consequence and likelihood descriptors for risks from exposure to hazardous substances,
  • determining the Risk Gap,
  • distinguishing risk-based decisions from administrative and compliance issues,
  • the application of Workplace Exposure Limits (WELs), and
  • the concept of As Low As Reasonably Practicable (ALARP).

Application of the EMM to the health risks arising from exposure to hazardous substances is a wide topic and touches upon a range of issues concerning; a variety of hazards, including such considerations as the concentration of the substance, the frequency and route of expose, the existence of established arrangements for setting exposure limits and the hierarchy of controls required by legislation. It is not possible to provide for all eventualities and therefore this guidance is intended to be used as an outline or a set of principles to be followed when considering the appropriate level of enforcement action.

Determining actual and benchmark risks

Actual risk

Inspectors will be familiar with the process of determining the risk gap by comparing the risk associated with the situation they encounter (Actual Risk) with the risk associated with the situation as it should be, had the dutyholder fully complied with legal requirements (Benchmark Risk). The comparison of Actual and Benchmark Risks is achieved by means of the appropriate Risk Gap Table in the EMM. This process indicates whether the gap is Extreme, Substantial, Moderate or Nominal. Once the Risk Gap has been determined, a comparison with the relevant Compliance Standard indicates the Initial Enforcement Expectation that can be confirmed or modified by consideration of Dutyholder Factors and Strategic factors.

The principle has been established that when considering risks to health, inspectors should seek to determine the most credible health outcome. Accordingly, exposure to chemical agents can result in Serious, Significant or Minor health effects. By means of reference to levels of exposure to different classes of chemical agents, the tables in Appendix 1 are intended to assist inspectors decide whether the most credible health outcomes are; Serious, Significant or Minor and whether those outcomes are Probable, Possible, Remote or Negligible. There is debate whether health effects can be deemed 'Nil', however this likelihood descriptor has been retained to ensure consistency.

The substances listed in Appendix 1 are based on the descriptions used in the European Regulation on Classification, Labelling and Packaging of Substances and Mixtures (CLP) Some of the CLP categories have been combined where enforcement options seem to be similar

For most risks arising from the use of hazardous substances the nature of the health outcome will be known and will be identified in labelling requirements (eg risk phrases) and in Material Safety Data Sheets (MSDS). Column 2 in the table suggests the most credible health outcome (MCHO) for the class of substance listed, but for enforcement purposes, inspectors should confirm this matter by reference to the relevant MSDS.

For some substances it will be necessary for inspectors to obtain basic information about the toxicology and potential health effects from exposure to the substance before using the model. OC130/5 provides general guidance on applying the EMM to health risks, and on determining the most credible health outcome.

Column 3 of the table contains consequence descriptors that correspond to the most credible health outcomes. In some instances the descriptors stated may appear counter intuitive. The descriptors have been selected in the knowledge that there can be a lack of precise evidence as to the extent of adverse health effects from exposure to the substances named or the likely sensitivity of the exposed tissue or of individuals

Appendix 1 makes extensive reference to 'exposure'. inspectors should apply judgement of the potential extent of exposure by taking into account all the factors including the frequency and duration of exposure and the required protective and preventive measures. The latter will include such elements as the condition and maintenance arrangements for ventilation equipment or PPE, the effect of inadequate provision of information and training, and the consequences of limited health surveillance. The judgement is not necessarily solely dependent on measured exposures against limits.

The risk descriptor tables use qualifying terms such as 'repeated' and 'prolonged' that are not defined. It is not possible to provide definitions that fit all circumstances but further guidance is given in the 'Notes' column for named circumstances. Inspectors need to apply professional judgement in these matters and seek specialist advice if necessary in particular cases.

Benchmark risk

Due to the wide variety of hazard and potential effects from hazardous substances, it is not possible to establish benchmark risks in advance for all situations. Inspectors will have to apply judgement taking into account whether all the relevant controls are in place including such issues as; risk assessment, physical control measures, systems of work, monitoring, training and health surveillance. Where possible, reference should be made to operational guidance on specific substances. Inspectors should bear in mind that where reasonably practicable the aim of the law is to eliminate, or control the likelihood of injury to a negligible level.

Workplace Exposure Limits (WELs) and As Low As Reasonably Practicable (ALARP)

The formal establishment of Workplace Exposure Limits (WEL) takes into account the toxicity of the substance in question and involves consideration of a balance between toxicity, uncertainty and the practicability of control. COSHH requires that any WEL approved for a substance hazardous to health is not exceeded and in respect of a carcinogen, mutagen, substance toxic to reproduction, or an asthmagen, exposure is reduced so far as is reasonably practicable, the equivalent to as low as reasonably practicable (ALARP), below the WEL.

It is not possible to describe what is required to reduce exposure to ALARP in all circumstances. Accordingly, inspectors will need to apply judgement to the individual situation that they are assessing and seek specialist advice if necessary.


None required.


Not applicable.


Not applicable.

Recording and Reporting

Not applicable.


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Updated 08.03.11