ABSTRACT
In this chapter, we discuss the main elements of engineering risk assessment. The focus will be
on the general techniques for risk assessment along with simple examples of using these
techniques for qualitative and quantitative risk assessments. Risk assessment techniques have
been used by both government and industry to estimate the safety, reliability, and effective-
ness of various products, processes, and facilities. A risk assessment may focus on the health
effects that occur when toxic chemicals and biological contaminants are released into the
environment or consumed by people. This type of risk assessment is referred to as a health
risk assessment. A risk assessment may focus on the adverse environmental, health, and
economic effects that can occur when an ‘‘engineered’’ system fails, due to natural or human-
initiated events followed by failure of protective or mitigative barriers, culminating in human,
environmental, and economical consequences (losses). This type of risk assessment is usually
referred to as engineering risk assessment. While we talk about both types of risk assessments,
the primary focus of this book and this chapter is on engineering risk assessment with
emphasis on safety risk assessment techniques. In an engineering risk assessment, the analyst
considers both the frequency of an event, initiating a scenario of subsequent failure events and
the probabilities of such failures within the engineering system. But in a health risk assess-
ment, the analyst assesses consequences from situations involving chronic releases of certain
amount of chemical and biological toxicants to the environment with no consideration of the
frequency or probability of such releases.
