Pollution factors can be solid, liquid or gaseous foreign matter which may reduce the dielectric strength or the specific surface resistances for the given Creepage distance of the Equipment.
Pollution is divided into 4 degrees, in accordance with the environmental conditions to be expected in around the Installation of Electrical Assembly/Equipment :
| Terms | Term Description | Application |
|---|---|---|
| Pollution Degree 1 | No pollution or only dry non-conductive pollution. It has no effect. | Electrical Assembly/Equipment in Clean room environments, Inside sealed components. |
| Pollution Degree 2 | Normally only non-conductive pollution. Temporary Condensation possible. | Electrical Assembly/Equipment in Offices, laboratories, test stations. |
| Pollution Degree 3 | Conductive and non-conductive pollution present. Condensation frequent. | Electrical Assembly/Equipment in Industrial and farming areas (under cover), unheated rooms, Boiler rooms. |
| Pollution Degree 4 | Pollution generates persistent conductivity caused by Conductive Dust, wet dust, rain or snow. | Electrical Assembly/Equipment for Outdoor use, remote stations. |