Reaction time refers to the time it takes for an appropriate party to detect, evaluate and respond to a potential hazard. This might include a reaction to prevent immediate injury, or the manipulation or management of the physical environment such the operation of machine controls. In many cases, a person may not perceive a hazard until it's actually encountered.
Reaction time is often used in the context of automobile safety to refer to the amount of time it takes a driver to notice a hazard on the road and react to it by swerving, braking or slowing down. However, it is an important terms in workplace safety because the type of reaction a person has to a hazardous situation may determine its outcome. For example, reflext reactions to hazardous situations are often wrong, and can increase the danger of the hazard. However, workers can be trained to react in safer ways to particular hazards.