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Diagnostics Analysis and Management System

his region, known as the ‘tolerability region’, accommodates people’s and society’s willingness to live with a particular risk so as to secure social and economic benefits. Benefits for which people and society tolerate risks typically include local employment, lower cost of production, personal convenience and the maintenance of general social infrastructure for example through the availability of electricity, food or water supplies. However, while people may tolerate risks for which they can see some benefits that outweigh them and as such will indeed engage voluntarily in activities which often involve high risks, in general they want the risks to be as low as possible. Moreover, they are far less tolerant of risks imposed on them and over which they have little control. The concept of tolerability implies that existing control measures should be periodically reviewed to ensure that they are both properly applied and that they take account of changes over time, as for example, the availability of new options for reducing or eliminating risks due to technical progress.

To lerab ility limits The dividing line between the unacceptable and tolerable regions must reflect society’s values at large and will depend on the nature of the hazards and the detriment they could give rise to. However, HSE has proposed that for hazardous events to which workers are exposed, a risk of death of 1 in 1,000 per year should be the dividing line between what is tolerable for the majority of workers for most of their working lives, and what is unacceptable for any but fairly exceptional groups. For members of the public who have a risk imposed on them “in the wider interest” HSE would set this limit at an order of magnitude lower – at 1 in 10,000 per annum. At the other end of the spectrum, HSE believes that an individual risk of death of 1 in 1,000,000 per annum for the public (including workers) corresponds to a very low level of risk and should be considered as broadly acceptable. In addition to those levels of individual risks, the HSE has suggested that the chance of an accident causing societal concerns due to multiple fatalities in a single event should be less than 1 in 1,000 per year and, if possible, less than 1 in 5,000 for accidents where there is some choice whether to accept the risk of it happening – for example by allowing the erection of a hazardous installation in a built-up area. The choice of the above figures is essentially a policy decision and they are not intended to be straight-jackets applied rigidly in all circumstances. The upper boundary was determined by analogy with high risk industries generally regarded as well regulated while the lower boundary