Environmental hazards are defined as extreme events or substances in the Earth and its ecosystem that may cause severe consequences for humans and the things they value. These include geophysical and meteorological phenomena such as earthquakes and droughts.
Environmental risk approaches have developed from an initial focus on preventing natural disasters through engineering work, to a focus on how human behavior and perceptions influence response to and adaptation to hazards, and then to an analysis of how political and economic processes and structures make some people and places more vulnerable to extreme events than others .
Environmental risk is often defined as the product of a hazard and its probability of occurrence, using a simple formula that defines risk as the product of the likelihood of an event occurring, measuring its severity in terms of the number of exposed populations, and the nature of the consequences.
Environmental risk assessment uses a wide range of empirical, statistical, and economic methods to estimate and compare the risks of pollution, technologies, and everyday activities.
Critical views of risk point to the limitations of quantitative assessments, including differences between general and ‘expert’ judgments, the unequal distribution of exposure to risk in space and society, and the ways in which risk is constructed and defined by different interest groups.