The European standards for off road diesel engines have been structured in four stages affecting all kinds of non-road engines. For example engines used in construction, agriculture, inland waterways and railroad appliances. Stage I to III have already come into force and have gradually reduced the allowed amount of harmful emission. The latest stage (IV) will be introduced in 2014 with more rigorous limitations of emission.
The first non-road diesel engine regulations were introduced in 1997. These stages did not yet include railroad engines, inland vessels or airplanes
Addressing a wider range of off road vehicles. Stage III and IV contain more elaborative and demanding standards. Stage IV will be introduced in 2014. These emission standards will also include locomotives, airplanes and inland ships. Stage IVB was introduced in 2011 causing major non-road suppliers to implement SCR technology.