risk perception

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					risk perception

When                                                    T
                                                                HE ACCURATE perception of risk by
                                                                all employees within an organisation
                                                                is important for effective health and
                                                        safety management. Accidents are more likely
                                                        to occur if employees do not identify all the
                                                        potential hazards, or misjudge the risk

is a                                                    involved in performing an operation. The
                                                        effectiveness of task risk assessments is
                                                        dependent on those performing the
                                                        assessment making accurate risk judgements.
                                                            Research investigating workers’ risk

                                                        perceptions has revealed that subjective risk
                                                        estimates differ from objective risk data in a
                                                        number of systematic ways. It is important
                                                        that organisations are aware of biases in
                                                        employees’ subjective assessment of risk, so
                                                        they can develop mechanisms to reduce the

not a
                                                        impact of these biases. Biases in risk
                                                        perception could affect the accuracy of task
                                                        risk assessments, at various stages in the
                                                        process, including the identification of the
                                                        hazards, assessment of the likelihood and
                                                        consequences, and the specification and

risk?                                                   implementation of control measures.
                                                            Concern about the accuracy of risk
                                                        assessments is highlighted by a recent TUC-
                                                        sponsored survey, which revealed that only
                                                        two in five safety representatives felt that risk
                                                        assessments carried out in their organisation
                                                        were adequate1. This finding is supported by
Our industrial psychology contributors                  the results of a small survey carried out at a
Mark Fleming and Ronny Lardner explore                  recent safety conference, which revealed that
the human factors aspects of risk perception            60% of safety managers who responded felt
                                                        that the accuracy of employee risk
                                                        assessments needed to be improved. In
                                                        addition, over half indicated that they were
                                                        aware of one or more recent accidents where
                                                        an inaccurate risk assessment was a causal
                                                        factor. Consequently, it is important to
                                                        understand the perceptual and behavioural
                                                        factors that influence the accuracy of front-
                                                        line employees’ risk assessments.

                                                        The dread factor
                                                        Research into public perception of risk
                                                        could provide useful information about how
                                                        new or inexperienced members of staff may
                                                        think about risk. These studies suggest that
                                                        the characteristics or features of a hazard,
                                                        such as the amount that is known about the
                                                        hazard, controllability of consequences and
                                                        the impact on future generations, influence
                                                        their perceptions. These hazard
                                                        characteristics can be summarised under
                                                        two headings, ‘dread’ and ‘unknown’.
                                                        Nuclear reactor accidents are an example of
                                                        a hazard that scores highly on the dread
                                                        factor. Hazards that score highly on the
                                                        unknown factor include electrical fields and
                                                        DNA technologies. If a hazard scores highly
                                                        on the dread or unknown factors, then
                                                        people are more likely to misjudge the risk
                                                        from this hazard 3.

14                              the chemical engineer                                        8 July 1999
                                                                                                                         risk perception

Biases in workers’ risk                         spoken about many years after the event
                                                                                                     The importance of
perceptions                                     occurred, which heightens workers’
Workers tend to underestimate the risk          concern when performing the operation.               task knowledge
                                                For example, railway workers overestimate            Two men were killed when they were
from tasks that they perform frequently2.
                                                the risk of riding on railroad car bumpers,          overcome by carbon monoxide
This bias has been called ‘risk habituation’.
                                                due to the vivid and gruesome nature of              produced by a petrol engine, which
It appears to be due to people becoming
                                                being crushed between the carriages.                 they had taken into a well to pump it
accustomed to being exposed to the
                                                    The overestimation of risk from a hazard         dry after flooding. Their lack of
hazards, therefore underestimating the risk
                                                can be just as problematic as                        knowledge about petrol-driven pumps
and becoming complacent about the
                                                underestimation. If workers are concerned            meant that they were unaware of the
hazards. This complacency may be due to
                                                about one hazardous aspect of an                     hazardous fumes that the pump was
the fact that they have performed the
                                                operation, they may not pay sufficient               likely to produce and did not identify
operation very often and have never
                                                attention to other hazards. For example              the hazard.
experienced an accident – a case of
                                                when workers are breaking into
familiarity breeding contempt. A number of
                                                hydrocarbon lines they tend to focus on the
practical steps can be taken to reduce the
                                                potential for oil or gas release and may not        inexperienced personnel may miss
impact of this bias. Risk communication
                                                pay enough attention to less dramatic               potential hazards.
programmes should make employees
                                                hazards like tripping or falling from a                 Research carried out in the forestry and
aware of this bias in their risk perceptions.
                                                height. Accident statistics would suggest           coal industries suggests that supervisors are
These campaigns should highlight hazard
                                                that it is the lower consequence but higher         more likely to underestimate risk than
potential and link this to the control
                                                likelihood hazards that are less well               front-line employees are2. It has been
measures used to reduce the risk. Risk
                                                controlled.                                         argued that supervisors tend to
communication should be occupation-
                                                    In order to mitigate against                    underestimate risk because for them, the
specific and highlight the hazards that
                                                overestimation bias, organisations need to          risk-benefit trade-off for the hazardous
employees are exposed to most frequently,
                                                develop mechanisms to ensure that                   activity is biased towards productivity and
and use actual accidents to highlight the
                                                employees take adequate cognisance of the           this can lead them to underestimate the
potential consequences.
                                                risks posed by all the hazards associated           risk. Involving team members in the risk
                                                with an operation. Providing information            assessment process to counter-balance the
 Consequences of risk                           on the risk assessment form, to prompt              supervisors’ underestimation of risk may
 habituation                                    workers to consider common hazards –                reduce the impact of this bias. This
 An experienced timber handler at a             such as tripping hazards – that might be            approach is supported by the finding that
 sawmill was killed when a stack of             omitted from the assessment, can reduce             offshore workers were less likely to be
 timber fell onto him. The handler              the impact of this bias. In addition, when          involved in an accident if their supervisor
 allowed the single stack to stand              communicating about risk, examples of               involved them in the risk assessment
 unsupported, although he was aware             previous accidents where an inaccurate risk         process5.
 of the hazard and had recently been            judgement was a causal factor will be
 reminded of the safe method of                 useful.                                             Reducing the impact of risk
 working, which suggests that he had               Risk perception research in a variety of         perception biases
 become complacent about the risk.              organisational settings has found that the
                                                                                                    In the past, risk perception researchers
                                                more practical knowledge an individual has
                                                                                                    assessed the accuracy of peoples’ risk
                                                about an activity, the more likely he is to
   On the other hand there is evidence to                                                           judgements by asking them to express their
                                                be able to identify all the hazards and have
suggest that workers overestimate the risk                                                          risk estimates in probabilistic terms (such
                                                accurate risk perceptions. So it is essential
from tasks that are notoriously dangerous,                                                          as number of fatalities per 100,000
                                                that those performing risk assessments have
operations that they perform infrequently                                                           exposed) 3. In general, these studies found
                                                the relevant practical experience of
or hazards that produce a feeling of ‘dread’                                                        little correlation between subjective risk
                                                performing the operation being assessed, as
or that they perceive as ‘unknown’ (see                                                             judgements and objective data, and
box – The dread factor). Workers appear to                                                                                 therefore concluded
overestimate the risk when they focus too                        characteristics of the consequences                       that the participants
much on the consequences and not                                     (eg dramatic or imaginable)                           did not have an
enough on the likelihood of the event                                                                                      accurate perception of
occurring. The risk from operations that are     knowledge                                                 frequency of    the risks. Recent
performed infrequently tends to be over-         of task                                                     performing    research has found
estimated because workers have less of a                                                                        the task   that the risk
feeling of control and expertise and so are                                                                                perceptions may, in
more concerned about the risk.                   situational            Risk perception                       perceived    fact, have been
   Workers also tend to focus on the             awareness                                                       control   accurate – but people
consequences of operations that have a                                                                                     found it difficult to
reputation for being notoriously dangerous                                                                                 express their risk
because their consequences tend to be                                                                                      perceptions in
vivid, imaginable or gruesome4. This means                                                           specification and
                                                 hazard                   assessment                                       probabilistic terms
that they are overly concerned about the                                                           implementation of
                                                 identification            of the risk                                     because this is not the
consequences and therefore overestimate                                                             control measures       way people think
the risk. In addition, any accidents that                                                                                  about risk. This
                                                v Model of risk perception and risk assessment
have occurred tend to continue to be                                                                                       suggests that

8 July 1999                                              the chemical engineer                                                                  15
risk perception

                                                            (or vice versa), the control measures          Future directions
Importance of situational                                   specified are unlikely to be adequate. It is   The effectiveness of risk communication
awareness                                                   therefore important that the risk              campaigns could be improved by
An explosion occurred in a tank                             assessment team or individual has an           increasing the credibility of the message.
containing aqueous waste that was                           overview of other operations or                People need to trust the communicator
contaminated with hydrocarbon solvent.                      individuals that may alter the risk profile    to believe the message being conveyed.
Welding work was being carried out on                       of the operation that they are performing.     It may well be worth including
pipework supports carrying pipes that                          An important practical consideration        workforce representatives or unions in
led into the top of the tank. The welding                   when specifying risk assessment                the campaign, as they are likely to be
ignited fumes in the pipes and the flames                   procedures is the timing of the risk           trusted by the workforce. The
spread along the pipes into the tank. The                   assessment in relation to when the task is     development of mechanisms that
explosion hazard had not been identified                    going to be performed. An inspection           heighten employees’ awareness of the
because the risks associated with                           project carried out by the offshore safety     importance of low consequence but
surrounding plant and equipment were                        division of the HSE concluded that a high      high likelihood hazards when
not adequately considered. In other                         proportion of risk assessments were being      performing a risk assessment may also
words, the individual assessing the risks                   performed too close to the worksite (in        be worth considering.
did not have adequate situational                           terms of time and seniority), which               Another promising area of future
awareness.                                                  reduced their effectiveness. If the risk       investigation is the development of
                                                            assessment is carried out just before the      decision support systems to assist
assessment procedures are likely to be                      operation starts, it may limit the control     workers in performing task risk
most effective if they are designed to                      measures that can be put into place due to     assessments. A decision support system
enable employees to express their risk                      time constraints. In addition, those who       could reduce the impact of biases in risk
estimates in simple terms (low, medium,                     carry out the risk assessment require          perception by removing the need for
high). Offshore safety research has found                   access to the resources to be able to          front-line employees to make probability
that workers’ relative ‘feelings of safety’                 implement the control measures they            and severity estimates. It may be
about the risk from a range of hazards are                  specify in the risk assessment. If they can    possible to use the results of generic risk
reasonably accurate when compared with                      only specify standard control measures,        assessments to support employees
more objective measures such as accident                    such as personal protective equipment,         performing task-specific assessments.
statistics and quantitative risk assessment                 then the risk assessment process can be        For example, a major petrochemical
results. It therefore might be useful to get                devalued.                                      company has developed a computer-
employees to rank the hazards identified                       Are task risk assessments performed by      based risk assessment support system
instead of making likelihood and                            people that have the authority and             that suggests control measures based
consequence judgements for each hazard.                     resources required to implement additional     on the hazards identified by the
   Situational awareness is critical when                   control measures they feel are required?       employee. s
assessing the risks associated with an                          Do risk communication campaigns
operation. If front-line employees are not                  address biases in risk perception in           For further information Mark Fleming
aware of the other operations, individuals,                 order to combat complacency about              and Ronny Lardner can be contacted at
or activities that may affect their operation               operations frequently performed?               The Keil Centre, Chartered Psychologists,
                                                                                                           5 South Lauder Road, Edinburgh, EH9
 How effective is your risk assessment process?                                                            2LJ, tel +44 131 667 8059, fax +44 131
                                                                                                           667 7946, email:

 Mechanisms to reduce the impact of risk perception biases                                     Yes   No
 1. Are risk assessments performed by an individual or a team with the following skills:                   1. Dwyer, J, Don’t gamble on risks. Works
          Practical knowledge of the operation being assessed?                                 t     t
                                                                                                           Management (pp 17–21). (October 1998).
          Knowledge of risk assessment techniques?                                             t     t
          Overview of other factors (such as operations) that may influence the risk?          t     t
                                                                                                           2. ACSNI. Human Factors Study Group Third
 2. Do risk assessment training courses provide skills training to reduce the impact of                    Report: Organising for Safety. London: HMSO
 known risk perception biases?                                                                 t     t     (1993).

 3. Are the workers that are going to perform the operation involved in the risk assessment?   t     t     3. Royal Society. Risk, Analysis, Perception,
                                                                                                           Management. London: The Royal Society
 4. Is the accuracy of risk assessments performed by front-line employees monitored?           t     t     (1992).
 5. Was the way workers think about risk considered when risk assessment processes,                        4. Zimolong, B. Hazard perception and risk
 procedures and documents were being designed?                                                 t     t
                                                                                                           estimation in accident causation. In RE Eberts
 6. Do risk assessment procedures ensure that task-specific risk assessments are performed                 & CG Ederts (Eds.), Trends in Ergonomics/
 early enough to ensure that sufficient time is available to implement control measures?       t     t     Human Factors II (pp 463–470). Amsterdam:
                                                                                                           Elsevier Science Publishers (1985).
 7. Are task risk assessments performed by people that have the authority and resources
 required to implement additional control measures they feel are required?                     t     t     5. Fleming, M. Supervisors’ management of
                                                                                                           safety in the offshore oil industry, HSE OSD
 8. Do risk communication campaigns address biases in risk perception in order to combat
                                                                                               t     t
                                                                                                           report Suffolk: HSE Books (in press).
 complacency about operations frequently performed?

16                                                                      the chemical engineer                                                  8 July 1999

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