This scheme should not be confused with the Ultra Low Emission Zone (ULEZ), introduced in April 2019, which applies to all vehicles.

The low emission zone started operating on 4 February 2008 with phased introduction of an increasingly stricter regime until 3 January 2012.

[3][4][5] The Green Party reported that nine sites in London exceeded the EU limits for air pollution in 2007.

In 2007 Transport for London (TfL) estimated that there were 1,000 premature deaths and a further 1,000 hospital admissions annually due to poor air quality from all causes.

Under this new scheme, a daily charge would be applied to the vehicles responsible for most of London's road traffic emissions, commercial vehicles—such as lorries, buses, and coaches, with diesel engines.

[3] The LEZ came into operation on 4 February 2008[13] with a phased introduction of further provisions as increasingly tough emissions standards apply.

[14] Vehicles registered after October 2001 are generally compliant with the first stages of the zone when Euro 3 engine compliance was the mandatory requirement.

On 2 February 2009 the Mayor of London, Boris Johnson, announced his intention to cancel the third phase of the LEZ covering vans from 2010, subject to the outcome of a public consultation later in the year.

[17] Statistics from TfL showed that the number of vehicles complying rose to nearly 90% upon the introduction of tougher standards in March 2021, up from 70% in May 2019.

[3] For vehicles registered outside of Great Britain, an international debt recovery agency is used to obtain unpaid charges and fines.

[27] The Road Haulage Association opposed the scheme, stating the costs to hauliers and benefits to the environment did not justify its introduction.

[3] Schools and St John Ambulance have expressed concern about the additional costs that the scheme will bring them, particularly in light of the restricted budgets they operate under.

[7] London First, a business organisation, criticised aspects of the scheme with relation to the categorisation of vehicles, but supported the principle.

One month after its introduction, the number of the worst polluting vehicles entering the zone each day had dropped from 35,578 to 26,195.