Science, Maths & Technology

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Assessing risk in engineering, work and life

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# Example 2 Assessing the acceptability of risk

In 2015, the NHS estimated that around 100 000 people die as a result of smoking each year in the UK (NHS, 2015). According to the UK’s Office for National Statistics, in 2014 19% of the British population (around 12 million people) were smokers (ONS, 2016). Is this risk acceptable to smokers, and would a similar risk from travelling on the railways be acceptable?

Solution

Many smokers would say that this risk is unacceptable and that they are trying to give up smoking, but some smokers do consider the risk to be acceptable and have no intention of giving up.

There are about 2.9 million rail season ticket holders in the UK. Applying the same rate of fatalities (100 000 per 12 million or 1 in 120) this would equate to over 24 000 deaths on the railways each year. Clearly this would be completely unacceptable to rail travellers, the population as a whole, the rail industry, politicians and the international community.

The difference is that the risk from smoking is, at least to some extent, voluntary, while the risk from rail travel is completely outside the passengers’ control.

## Activity 2 Acceptability of risk

Timing: Allow approximately 15 minutes.

Decide whether each of the following factors would be likely to make a risk more or less acceptable to people.

• The effect is immediate rather than long term.
• There are many alternative ways of achieving the intended aim.
• The risk is unknown or not known with certainty.
• Exposure is an essential part of life (rather than a ‘luxury’).
• The risk is unexpected.
• The hazard is a common one.
• Only sensitive people are affected by the risk.
• The consequences of the risk are reversible.

Greater acceptability:

• The effect is immediate rather than long term.
• Exposure is an essential part of life (rather than a ‘luxury’).
• The hazard is a common one.
• The consequences of the risk are reversible.

Lower acceptability:

• There are many alternative ways of achieving the intended aim.
• The risk is unknown or not known with certainty.
• The risk is unexpected.
• Only sensitive people are affected by the risk.

The way people treat risks depends on their perception of how those risks relate to them and things they value. This evaluation might relate not only to physical harm, but also to social and political beliefs and degree of trust in the information provided. Members of the public and experts often disagree. Engineers are engaged in this process occupationally, or perhaps in relation to a project they are involved with or any associated evaluation of that activity and appropriate communication. However, it is important to remember that there is no such thing as absolute safety!

So far you have looked at definitions and perception related to risk. To approach the estimation of risk in a more scientific and calculated manner, it is now worth studying the statistical aspects of risk as described by probability.