Resolved upon improving air quality for public health and environmental reasons, the European Union has been progressively stiffening its regulations on polluting motor vehicle emissions. A series of EU standards have helped reduce pollution from new diesel and spark ignition vehicles (passenger cars and light commercial vehicles) by obliging manufacturers to optimize technology and develop new tailpipe emission post-treatment systems. At the same time, improvements in motor fuel quality were made, without which it would have been pointless to install the new emissions reduction systems.

The new Euro 5 and Euro 6 standards, effective 1 September 2009 and 1 September 2014 for new passenger and light commercial vehicles, will set stricter limits on particulate emissions (the same for diesel and gasoline vehicles) and introduce a limit on the number of particles. The latter will be implemented during an intermediate stage: Euro 5+ (2011).