The aim of the scheme is to improve air quality in the city by deterring the most polluting vehicles from driving within Greater London.

The first phase of the Low Emission Zone, which applies to lorries over 12 tonnes, began on 4 February 2008. The scheme extended on 7 July to include lorries over 3.5 tonnes, buses and coaches. Cars and motorcycles are not affected by the scheme.

Reduced traffic pollution will improve the health and quality of life of people who live in, work in and visit London.

There are no barriers or tollbooths required for this enforcement system. The Low Emission Zone is enforced through PIPS fixed site Spike+ ANPR cameras, which read the vehicle registration number plate as vehicles drive within the LEZ and check it against a database of vehicles which meet the LEZ emissions standards, or are either exempt or registered for the 100 percent discount, or if the LEZ daily charge has been paid. PIPS Spike+ cameras check against a database, which is compiled using data from the Driver and Vehicle Licensing Agency (DVLA), the Vehicle and Operator Services Agency (VOSA) and the Society of Motor Manufacturers and Traders (SMMT), together with information from vehicles operators who register their details with Transport for London (TFL).