So-called frictional electricity. Contact potentials due to the different electronegativity lead to charge separation between contacting media and therefore to a potential difference. In case of insulating media, the charge cannot flow off and high voltages can occur. Therefore, synthetic fibre textiles, carpets and plastic conveyor belts tend to get electrically charged. The field strengths caused by electrostatic charge can be so high that lightning discharge can occur. Nevertheless, electrostatic charge is not dangerous for humans because only very small amounts of charge are generated. Very sensitive electronic components, on the other hand, may be damaged.
Potentially explosive media (e.g. coal dust) in the vicinity of a lightning discharge may cause explosions. Different plasma coatings, such as DLC coats, can provide protection from electrostatic charge.