Collective risk

The tolerable collective, group or societal risk is usually fixed using the relation 

1) h is the annual frequency for the occurrence of the damaging event and X the volume of damage associated with it (e.g. number of fatalities) n is the coefficient of risk aversion, which is usually chosen to be 1. In this way a larger weight is assigned to the volume of damage, which has a special impact for catastrophes involving many fatalities. 

In the Netherlands the relationship for the risk limits shown in Fig. 8.3 applies. The corresponding coefficient of risk aversion is n = 2. 

In Switzerland (canton Ziirich or e.g. Basel as well) the hmit values of Fig. 8.4 are in use. 

As long as there are no official values in Germany the author proposes to use the individual risk value (location risk) of the Netherlands, i.e. 10 a , and for the societal risk the limits applied in Switzerland (Zurich). The latter were used as well by the German Major Accident Commission in its expert opinion on the extension of the Frankfurt Airport [34]. 

---

Aggregate risk is used to measure the collective risk to people in a facility who could be exposed to an event or events. It indicates the frequency that a specified number of people will suffer a specific level of harm (e.g., death). Just as is the case with societal risk, aggregate risk can be expressed in terms of the frequency distribution of multiple-casualty events. 

Foster, M.W. et al., "The Role of Community Review in Evaluating the Collective Risks of Human Genetic Variation Research, Am. J. Hum. Genet., 64, 1719-1727 (1999). 

W = probability of event t = probability of presence A = probability of fatal injury Then, one evaluates collective risk R, as... 

Exposed Persons COLLECTIVE RISK OF SINGLE EVENT... 

Because of their significant public benefits, vaccines are subject to significant collective action problems (Olson 1965). Individual and collective risks and benefits... 

Finding 4-1. A Phase 1 QRA for using a baseline incineration system at Pueblo has been completed, and the point estimation of the impact on public health indicates that the risk to the public due to accidental releases would be extremely low. The HRA for Pueblo has not yet been completed. Several additional analyses are being conducted to support operational and design decisions for a modified baseline process. It is not clear how the Army is going to use the collective risk information it has or is seeking and in what framework this information will be used. 

Considering these past and expected trends, OECD has launched a new initiative, called Chemical Product Policy (CPP), to support Member countries and others manage lifecycle environmental risks from chemicals. The first phase of this initiative involved identifying activities that could support each phase in the chemical management process (i.e., data generation/collection, risk assessment, and risk... 

From this point of view we consider it to be justified and necessary that technical and natural scientific assessments and social risk perceptions be brought together within rational risk evaluations (Fiorino, 1989). Now the question arises of how societies should decide on fundamental procedures concerning uncertain consequences of collective risks. Which strategy should a society choose if the consequences of risky actions concern many people with different preferences Philosophers and decision-making the-... 

In assessing risk it is necessary to consider each use of the pesticide, the potential alternatives which may be used to fill a pest control vacuum and their relative risk, the individual and collective risks to users of the pesticide, workers exposed in subsequent agricultural or other activities, consumers of treated food, people who live nearby and those exposed through environmental contamination. Other descriptors of the nature of the risks are also germane ... 

Where there is a risk of about 10 year that individuals may become casualties, steps are usually taken to reduce the risk if possible—thus, the present day concern of society to reduce the death toll from traffic accidents. As the risk diminishes, concern and countermeasures become less in evidence. For risks less than 10 year , the individual does not appear to worry much, and so elaborate precautions against the risk are seldom taken—we do not pass our lives in constant fear of being struck by lightning. Some consider that in these thoughts lies a possible clue to the level of risk from nuclear power that may be acceptable to the individual. This may well be true, and we discuss the matter further below however, experience of debate about reactor siting, and common experience of life and of the daily news which most affect people s actions and reactions may persuade us that it is the collective risk of numbers of people or a group that should provide the basis of a criterion of overriding importance in relation to risk from nuclear power. This also is discussed further in this section. 

Collective risks are represented by so-called complementary frequency distributions. These indicate the expected frequencies for the occurrence of a damage which is larger than a certain value. For example. Fig. 8.6 shows the frequency... 

Fig. 8.6 Complementary frequency distribution of the collective risk caused by the failure of a pipeline (result of Case study of Sect. 10.11)...

Fig. 10.49 Complementary frequency distribution for the collective risk caused by the pipeline...

It is obvious that the criterion for the collective risk is fulfilled, too. 

In general, the collective risk to society from the operation of a set of n identical, small power reactors, each delivering the same lifetime energy output e, but to different populations Pi, must be shown to be less than that from die operation of one large reactor of eneigy output s ne to a population P = X.-/ ,- in similar circumstances. 

Corresponding to the above-mentioned three aspects of the safety problem, individual risk, real collective risk, and perceived collective risk are identified. The real collective risk of an event—a statistical expected value—is given by the sum of all individual risks caused by the event. The perceived collective risk is the real collective risk increased by an aversion function that takes into account that the reaction of the public is much more violent to rare events with large consequences than to more frequent events with fewer consequences per accident. 

Individual risk Real collective risk Perceived collective risk ... 

FIGURE 12.9 Limiting collective risks in the specific case by marginal cost for safety measures. 

FIGURE 12.10 Frequency/consequence safety criteria and ALARP principle for the collective risk. 

FIGURE 1Z13 Case study explosives transport sources of collective risk. 

Applying the above-mentioned willingness-to-pay criterion, the risk reduction would have justified this investment. But the question remained whether the safety could be improved more effectively by other safety measures. In order to answer this question, the contributing factors to the collective risk of the manual supply system were analyzed. It was demonstrably the case that ... 

---