European emission standards (called Euro norms) set limits on the amount of pollutants that can be released from vehicles. The standards have become increasingly stringent over time, regulating emissions of nitrogen oxides, hydrocarbons, carbon monoxide, and particulate matter. The document reviews the development of standards for various vehicle types, including passenger cars, light commercial vehicles, lorries, buses and more. Standards differ depending on the vehicle weight and size. The latest standards are Euro 6 for cars and Euro VI for other vehicles.