Broadly speaking, a risk assessment is the combined effort of: identifying and analyzing potential events that may negatively impact individuals, assets, and/or the environment; and making judgments "on the tolerability of the risk on the basis of a risk analysis" while considering influencing factors.
Risk assessment can also be made on a much larger "systems" scale, for example assessing the risks of a nuclear power plant (an interactively complex mechanical, electronic, nuclear, and human system) or a hurricane (a complex meteorological and geographical system). Systems may be defined as linear and nonlinear (or complex), where linear systems are predictable and relatively easy to understand given a change in input, and non-linear systems unpredictable when inputs are changed.As such, risk assessments of non-linear/complex systems tend to be more challenging.
In the engineering of complex systems, sophisticated risk assessments are often made within safety engineering and reliability engineering when it concerns threats to life, environment, or machine functioning. The agriculture, nuclear, aerospace, oil, railroad, and military industries have a long history of dealing with risk assessment.Also, medical, hospital, social service,and food industries control risks and perform risk assessments on a continual basis. Methods for assessment of risk may differ between industries and whether it pertains to general financial decisions or environmental, ecological, or public health risk assessment.