European rules affecting exhaust emissions from cars first came into force in 1970 and have been tightened up progressively ever since. This means that cars are cleaner now then they have ever been and are set to get cleaner still.
The limits form part of the European type approval regulations – a collection of safety and environmental tests which a new vehicle must pass before it can be sold in the European Union.
The latest Euro standards, Euro 4 (January 2005) and Euro 5 (September 2009) have concentrated on cleaning up emissions from diesel cars, especially reducing particulate matter(PM) and oxides of nitrogen (NOx). Some Euro 4 diesel cars were fitted with particulate filters, but all diesel cars need particulate filters to meet the requirements of Euro 5.