A Technical report intended for guidance for those in charge of writing immunity standards for an equipment or system, the purpose being to classify electromagnetic environments and help to improve the specification of the immunity requirements of an item containing electrical or electronic parts, obtaining electromagnetic compatibility. Supplies basic guidance for the selection of immunity levels. Applicable to any equipment, subsystem or system using electromagnetic energy and operating in a specific location as defined by this report. Does not describe environment inside transportation equipment (vehicles, traction, ships and aircraft), but includes their effect on the surrounding environment.