Low Emission Zones in Europe. Requirement, enforcement and air quality

The objective of low emission zones (LEZ) is to reduce particulate and NO2 emissions by preventing or limiting access for the most polluting vehicles. Initially, the measure was implemented to reduce particulate matter, mainly from heavy vehicles. Now the focus is also on reducing NO2 emissions. The requirements are generally more stringent for diesel vehicles than for petrol vehicles. LEZ was previously used primarily to reduce the use of older heavy vehicles, but several countries have now also introduced requirements for other categories of vehicles. An overweight of countries that have LEZ implemented the measure because they did not comply with the EU Limit Values. Effect of low emission zones (LEZs) on air quality is difficult to establish because of several methodology challenges. With improved knowledge on real emissions from road traffic the future LEZs can be better adapted to the cities’ needs.