the concept of prevention is based on four pillars. "firstly", the aim is the reduction of hazardous substances in vehicles to minimise their release to the environment. "secondly", vehicles should be designed to facilitate proper dismantling and to allow components and materials to be reused, recycled and/or recovered. "thirdly", the producers (both vehicle and component) shall increase the demand for recycled material. "finally", certain materials ("lead", "mercury", "cadmium", "hexavalent chromium") are forbidden except for a few applications with defined phase-out dates. these exemptions are catalogued in the annex ii to the elv directive.