We have looked at how dangerous some occupations can be, but how risky does something have to be before an organisation such as the HSE decides that something should be done? The HSE’s philosophy is based on what is known as the Tolerability of Risk framework, and can be rather nicely related to micromorts.
Basically, potential hazards are thought of as being on a spectrum of increasing risk, divided into three fairly loosely defined regions. At the top are “Unacceptable” risks – where something must be done to protect either the workers, or the public, or both, whatever the benefits of the activity may be. At the bottom are “broadly acceptable” risks, which are not exactly zero but are considered insignificant – the sort of thing we would regard as normal in our daily lives.
In between these extremes lie the “tolerable” risks – those that we may be prepared to put up with if there is sufficient benefit, such as providing valuable employment, personal convenience, or keeping the infrastructure of society going. After all, somebody has to do the dirty work.
Acceptable or not?
But how does anyone decide what is unacceptable, broadly acceptable, or tolerable? This cannot be necessarily put into numbers, but again we can turn to the HSE because they have come up with some rough rules-of-thumb.
First, they state that an occupational risk might be considered “unacceptable” if the chance of a worker being killed were greater than one in 1,000 per year. This equates to 1,000 micromorts per year, around the current level for commercial fishing. “Exceptional groups” are excluded from this: presumably serving in a war-zone counts as exceptional, for example, when the average risk faced by 10,000 servicemen and women in Afghanistan reached 33 micromorts a day, or around 10,000 a year.
For members of the public (rather than employed workers), the HSE considers a one in 10,000 a year risk – which is 100 micromorts a year – as being generally unacceptable. At the other extreme, risks are considered broadly acceptable if they are less than one in a million per year – or 1 micromort. This, by the way, is the current estimated risk of being killed by an asteroid.
But even such a minimal risk, if applied to the whole population of the UK, would mean around 50 deaths a year. So what would happen if these occurred all at once, say disasters with multiple fatalities, hazards that affect vulnerable groups such as young children, or risks imposed upon people just because of where they live?
In these circumstances, “societal concerns” can trump these cold micromort calculations. And again, the HSE has come up with some rough guidance that reflect these concerns: for any potential hazard, the risk of an accident involving 50 deaths should be less than 1 in 5,000 per annum. So let us say there is a dam, which, if it burst, would be likely to kill 50 people. In this case it needs to be designed so that this could be expected to happen only once every 5,000 years. This is a fairly stringent criterion. If 10,000 people live below the dam, that is less than 1 micromort a year each.
From an individual perspective this might be considered as being “acceptable”. But because we do not like disasters (although people clearly love reading about them in newspapers) then huge amounts of money are spent to make tiny risks even tinier.
So, perhaps it is time to unfurrow those brows and ungrit those teeth, and say hurray for health and safety!