ABSTRACT
This chapter considers the criteria, which are being, used more and more to pre-establish operational safety standards for major industrial installations and infrastructures projects. It describes the background to the criteria and discusses the manner in which criteria are being developed both for individuals and for the local community as a whole. The formal definition of risk combines the aspects of frequency and the consequences. Risk estimating is a developing science and predictions should only be an aid to decision making; many other factors have to be considered. There are two kinds of individual risk, the most exposed individual and the average individual. Societal risk criteria are generally more complex than individual criteria and there is less unanimity between practitioners. Risks falling in the top right area are generally high frequency, high consequence and represent the intolerable region where the risk is higher than society will tolerate.
