The Greater London Low Emission Zone (LEZ) introduces emissions standards throughout the 33 boroughs of London, for vehicles considered to be the most polluting. The LEZ will be in operation 24 hours a day, 365 days a year and has various stages dependent on vehicle weight and Euro standard. The scheme focuses on reducing particulate matter emitted from diesel-engined vehicles. This guide will provide details of the compliance standards and the options available to operate vehicles within the LEZ. This guide is for purchasers and managers of commercial vehicles