EN590 was introduced to coincide with the development of new emissions standards across the European Union & the UK. The overall goal has been to reduce the sulphur content of diesel fuel (a major element of pollution. eg. acid rain). However, Sulphur has been used as a lubricant in most fuels and its role has to be replicated by another chemical if the Sulphur content is to be significantly reduced. RemNOx Fuel Conditioners provide that lubricity.