A wide range of voltages can be dangerous for different reasons. A very low voltage (such as that produced by a single torch battery) can produce a spark powerful enough to ignite an explosive atmosphere. Batteries (such as those in motor vehicles) can also overheat or explode if they are shorted.If a person comes into contact with a voltage above about 50 volts AC, they can receive a range of injuries, including those directly resulting from electrical shock (problems with breathing, heart function etc); and indirect effects resulting from loss of control (such as falling from height or coming into contact with moving machinery). The chance of being injured by an electric shock increases where it is damp or where there is a lot of metalwork.Electrical or thermal burns can also occur from the flow of electrical current or hot surfaces, see: Electrical injuries.