Qualitative risk assessments

Risk assessment can be qualitative or quantitative. We shall deal with qualitative risk assessment first. 

In order to carry out a qualitative risk assessment, a way must be found to describe both the severity of a hazard and the probability of its occurrence. In each case, the exercise by the designers of considerable skill and judgment is needed, and the answers may well depend on local circumstances and the type of process or industry under consideration. 

A low severity hazard might, for example, be one that is most likely to cause an interruption to production, or inconvenience to the workforce or people living near the plant. A medium level of severity could be a hazard likely to cause injuries to people. A high level of severity is one where the outcome of the hazard is probably one or more fatalities. A hazard may also be measured in financial terms from low severity (small financial implications) to high severity (crippling financial loss to an organisation). 

The probability of a hazard may be described in qualitative terms as rather unlikely , unlikely and very unlikely . These terms have been selected to emphasise that we are normally dealing with uncommon events if a hazardous event is thought to be more probable than rather unlikely , appropriate steps to modify the design should be undertaken without further analysis. 

Hazard Probability - Hazard Severity i VERY UNLIKELY UNLIKELY RATHER UNLIKELY 

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Altliough the technical conununity has come a long way in understanding how to do a better job in luizard identification, dose-response assessment, and exposure assessment portions of risk assessment, it lias only begun to understand how to best cluiractcrize hcaltli risks and how to present tliese risks most appropriately to both the public and decision makers. Tlie next tliree sections specifically address tlicse issues. Tliis section deals witli qualitative risk assessment while tlie next two sections deal witli quantitative risk assessment. 

Because few generic frequency data were available on VCEs in similar facilities, a risk screening per Chapter 4 of this book was not performed. Instead, as a next step, the decision was made to perform a qualitative risk assessment. 

For acute toxicity, corrosivity and skin and eye irritation, values for the NOEL (or NOAEL or LOAEL) are not derived. Therefore, the only option is to determine whether the substance has an inherent capacity to cause such effects and to make a qualitative risk assessment to evaluate the likelihood of an adverse effect occurring in use. 

FDA provides a website with public information on this issue, " as well as specific guidance for industry. " " " These documents describe a process for deciding if a proposed antimicrobial use in food animals would likely lead to resistance that would negatively impact human health. It outlines possible methods for ranking antimicrobials based on their importance for human use conducting a qualitative risk assessment for a proposed animal antimicrobial use and managing risks identified in the assessment. 

Identification of Pathways. The expert system will guide a user to consider the variety of exposure pathways that should be considered for a site, and thus to perform a qualitative risk assessment. It helps to ensure that significant current or potential exposure pathways are not ignored. 

Qualitative Risk Assessment of Reproductive Health Disorders... 

TABLE 4. Qualitative risk assessment for health of mothers and new-born babies depending on working conditions classes of mothers before pregnancy. 

Quantitative or qualitative risk assessment, which may require expert judgement. Potential for use of expert systems for preliminary assessments. 

Our intention of applying RIPBR to digital I C system is to reduce unnecessary conservatism existed in QA requirements. To justify such reduction, RG 1.174 requires an assessment of risk impact due to the proposed reduction. However, current state-of-art PRA techniques do not support an acceptable quantitative risk assessment for a typical QA program. Fortunately, RG 1.176 accepts a qualitative risk assessment for the graded QA activities that do not have quantitative PRA data. In this section, we will present our proposed approach to such assessment. 

The Information System of Logistics has been used for the choice of a mUitary installation to examine risks of occupational exposure to NIEMR. Checklist Analysis method (Dickert, T.G. 1974) has been applied for identifying NIEMR sources and traditional brainstorming (Beranek, Z. et al. 1996) for qualitative risk assessment. 

The safety requirement can be reviewed with qualitative risk assessments such as HAZID or HAZOP. The reliabihty requirement is usually expressed as SIL... 

Table 2.1 Level 1 qualitative risk-assessment matrix...

Sound quantitative data on incident probabilities are seldom available. My associates skilled in system safety, a field in which quantitative risk assessments are routine, are not overly pleased when I say that most quantitative risk assessments are really qualitative risk assessments because so many judgments have to be made in the process to decide on the probability levels to be selected. 

Some who oppose the use of qualitative risk assessment techniques do so because the outcomes are not stated in absolutely assured, precise numbers. Such accuracy is not attainable because incident probability data are lacking and the severity of event outcomes is a best estimate. Expecting such results is unrealistic. Fortunately, recognition continues to grow that hazard analysis and risk assessment methods, although qualitative, add value to safety decision making. 

However, the world of risk assessment is in transition. Some systems now in use are three- or four-dimensional, and they require numerical risk scorings. Safety professionals can expect that variations of numerical risk scoring systems will proliferate. Nevertheless, it needs to be said that two-dimensional, qualitative risk assessment systems are not obsolete. Often, a two-dimensional system will be selected because it is sufficient for the hazards and risks encountered and it works well within an organization. This chapter will inform safety professionals on ... 

An opposite approach to quantitative risk assessment is a subjective and qualitative risk assessment by inspection. This needs to be carried out by experienced and competent people who are conversant with the hazards of the substances and exactly how those substances should be handled. Being subjective, this approach cannot be mathematically validated but it is by far the most practical method. However, it does require a good experienced... 

QUALITATIVE RISK ASSESSMENT RISK RESPONSE ACTION... 

HAZID method is a qualitative risk assessment method. It is a common and frequently used technique within the petroleum industry and in offshore processes. NORSOK Z013 2010 (mainly based on ISO/IEC 31000) is quite relevant in this sector of industry. Therefore, here relevant parts of the standard related to HAZID have been included in brief. The requirements to the hazard identification are as follows ... 

A. Kianmehr, N. Nahhani, F. Jaderi, Qualitative risk assessment approach based on HAZID method in Sirri Island gas compression andexport facility, Technical Journal of Engineering and Applied Sciences, 2013. TJEAS Journal 2013-3-23/3405-3409. 

Qualitative Risk Assessment An examination of system risk based upon established criteria that allow the analyst to evaluate risk levels in relation to other risks or total system risk. 

The more common form of risk assessment is the qualitative assessment which is based purely on personal judgement and is normally defined as high, medium or low. Qualitative risk assessments are usually satisfactory since the definition (high, medium or low) is normally used to determine the time frame in which further action is to be taken. 

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