Temperature

Temperature is either heat or cold which can cause harm to humans or damage equipment. For example if a human is exposed to heat for an extended period of time at some point the body will start absorbing more heat than it can dissipate. That leads to heat stroke. Exposure to cold for an extended period of time can lead to hypothermia. This is a state when the body temperature drops below the level required for normal metabolism. Cases when extreme temperature can damage equipment include: water left in piping below freezing temperature will burst the pipe; or malfunctioning cooling system of an engine leading to overheating.

We need to stress that included in this energy source are open flames, sparks, etc that can potentially be ignition sources. They may not necessarily have a high temperature to cause harm to a human or damage to an equipment but if they occur in the area where flammable mixture can be present the consequences could be disastrous.