A housing estate of 250 people is considered to be at risk from a nearby factory on the basis of a hazard analysis which yielded the following data:
(i) The 20% probability of fatalities due to the blast effects of an explosion.
(ii) The 10% probability of additional fatalities due to the release of toxic gas following the explosion.
(iii) The probable frequency of an explosion occurring is once in ten thousand years, i.e. 0.0001 yr-1.
QUESTIONS
(a) Find the societal and respective average individual risks for these events.
(b) Explain why such data may be misleading if the number of people exposed to the risks is increased by, for example, the expansion of the housing estate.