Residual risk, defined

The use of cost-benefit analysis plays an important role in the decision-making process for fire protection systems. A cost-benefit analysis sums the expected benefits and is divided by the sum of the expected costs. A challenge often lies in determining what "expected" means and estimating the value of money over the time period the fire protection is in use. In fire protection, the expected benefits can be defined as the difference between the cost of a loss without protection and the cost of a loss with protection. The exported costs include the initial costs of the fire protection as well as any annual testing and maintenance costs. The likelihood of an incident is factored in to obtain residual risk. This residual risk is compared to the benefit to determine what benefit is available each year versus the annualized cost. 

Thus, the risk analysis must be well prepared, meaning that the scope of the analysis must be clearly defined data must be available and evaluated, to define the safe process conditions and the critical limits. Then, and only then, the systematic search for process deviations from the safe conditions can be started. The identified deviations lead to the definition of scenarios, which can be assessed in terms of severity and probability of occurrence. This work can advantageously be summarized in a risk profile, enhancing the major risks that are beyond the accepted limits. For these risks, reduction measures can then be defined. The residual risk, that is, the risk remaining after implementation of the measures, can be assessed as before and documented in a residual risk profile showing the progress of the analysis and the risk improvement. These steps are reviewed in the next sections. 

This is the last step of risk analysis. After having completed the risk analysis and defined the measures to reduce risks, a further risk assessment must be carried out to ensure risks are reduced to an accepted level. The risks cannot be completely eliminated risk zero does not exist, thus a residual risk remains. This is also because only identified risks were reduced by the planned measures. Thus, the residual risk has three components ... 

Residual risk is defined as the risk remaining after protective measures have been taken (ISO/IEC Guide 51, 3.9). 

There can be no absolute safety some risk will remain, defined in this Guide as residual risk. Therefore a product, process or service can only be relatively safe. 

To repeat the previous quote from ISO/IEC Guide 51, There can be no absolute safety some risk will remain, defined in this Guide as residual risk. In the real world, attaining zero risk, whether in the design process or in operations, is not possible. Nevertheless, the residual risk, after risk avoidance, elimination, or control measures are taken, should be acceptable, as judged by the decision makers. 

Risk The probability during a period of activity that a hazard will result in an accident with definable consequences Safe A condition wherein risks are as low as practicable and present no significant residual risk... 

Documentation of a qualitative method may be a simple description of the issue dealt with, including assessment of associated risks and a conclusion regarding necessary action, if any. Though simple, such a QRM process should also be documented which risks were defined and balanced and who accepted the residual risk. 

Residual risk Risk can never be eliminated entirely, though it can be substantially reduced through application of the hierarchy of controls. Residual risk is defined as the remaining risk after controls have been implemented. It is the organization s responsibility to determine whether the residual risk is acceptable for each task and associated hazard. Where the residual risk is not acceptable, further actions must be taken to reduce risk. 

Residual risk is defined as the risk remaining after preventive measures have been taken. No matter how effective the preventive actions, there will always be residual risk if an activity continues. Attaining zero risk is not possible. If the residual risk is not acceptable, the action outline set forth in the foregoing hazard analysis and risk assessment process would be applied again. 

The process risk of a particular event is related to how often the event could occur and the severity of the consequences if it does. Compare the process risk to facility risk criteria to determine if the risk is tolerable or whether additional protection is required to reduce it below the defined criteria. Residual risk represents a likelihood that an unacceptable consequence could occur, so drive it as low as reasonably practicable. ISA-TR84.00.04-1 Annex J provides guidance on how to address process risk that requires SIL 4 equivalent risk reduction. 

The release procedure is defined following almost exactly the correspondence process of ISO 62304 in case the version is an official main release, and especially if it is to be submitted for approval of a regulatory body (typical FDA 510(k) clearance or CE mark), the overall residual risk is to be evaluated and documenting it takes into account the verification and validation of risk mitigations and the remaining open risks. 

The UK Health and Safety at Work Act 1974 defined the concept of as low as reasonable practicable (ALARP). The ALARP principle is based on reasonable practicability, which simply means that hazard controls are implemented to reduce residual risk to a reasonable level of practicality. For a risk to be considered ALARP, it must be demonstrated that the cost in reducing the residual risk further would be grossly disproportionate to the benefit gained. Therefore, a risk assessment is conducted, and a cost-benefit analysis performed to determine how far to carry the hazard control. Of course, the challenge is deciding what is practical (e.g., cost, effort, time) balanced with how much benefit of lower residual risk the hazard control brings. Unfortunately, there is no standard method to demonstrate that the hazard control trade-off will meet ALARP. However, some of the following have been successfully used ... 

Process that relies on industry defining what society will tolerate as an acceptable level of residual risk. 

Risk-based analysis, described further in Ghapter 11, is defined as an approach to evaluation and decision-making that explicitly, and to the extent practical, analytically incorporates considerations of risk and uncertainty. Risk-based analysis shall be used to compare plans in terms of the likelihood and variability of their physical performance, economic success, and residual risks. A risk-based approach to water resources planning captures and quantifies the extent of risk and uncertainty in the various planning and design... 

The Hazard Consequence Report (which can be considered as a residual risk report) is used to identify the applicable safety requirements based primarily on the consequence severity. The specific means by which these requirements are implemented are defined by safety and engineering personnel and documented on the relevant Hazardous Condition Report(s). This may involve selecting the appropriate specific safety requirement or safety design feature. 

Assessing risks, developing risk reduction alternatives, and defining residual risk concerns and issues. 

Pubhc concerns about pesticides in the diet of infants and children resulted in an expert committee convened by the U.S. National Academy of Sciences which devoted four years to the review of all available data. A consensus report was issued in 1993 (80). A number of recommendations for further work to more precisely define what constitutes the diet of infants and children were made. No risk could be estimated. The residue data reviewed by the panel were mainly from monitoring studies conducted by the PDA using multiresidue methods to analyze fresh produce and market basket samples collected from various geographic areas (81,82). These and other rehable scientific studies have demonstrated that relatively few food samples contain detectable residues. Most residues are far below estabhshed tolerances which are set above the maximum residue found in treated raw agricultural... 

---