European emission standards

European emission standards are sets of requirements defining the acceptable limits for exhaust emissions of new vehicles sold in EU member states. The emission standards are defined in a series of European unio directives staging the progressive introduction of increasingly stringent standards. Currently, emissions of nitrogen oxide （NOx）, hydrocarbons （HC）, carbon monoxide （CO） and particulate matter （PM） are regulated for most vehicle types, including cars, lorries, trains, tractors and similar machinery, barges, but excluding seagoing ships and aeroplanes. For each vehicle type, different standards apply. Compliance is determined by running the engine at a standardised test cycle. Non-compliant vehicles cannot be sold in the EU, but new standards do not apply to vehicles already on the roads. No use of specific technologies is mandated to meet the standards, though available technology is considered when setting the standards.