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AirSeverity: Moderate

Traffic pollution and the Ultra Low Emission Zone in London

Nitrogen dioxide from traffic has been a long-standing problem, and London's low-emission zones have been extensively studied.

London · United Kingdom

01 · The problem

What is happening

After the Great Smog of 1952, the UK passed the Clean Air Act 1956, which reduced coal smoke. Modern pollution in London is dominated by road traffic, particularly diesel vehicles emitting nitrogen dioxide and particulates. London introduced the Ultra Low Emission Zone in central London in 2019, expanded it in 2021 and extended it London-wide in 2023. City Hall has reported large reductions in roadside nitrogen dioxide since the scheme began, although fine particulate levels remain above WHO guideline values.

Moderate severity. Material effects on people or ecosystems; actively managed. Severity is descriptive editorial metadata summarising documented effects. It is not a measured index or a score.

02 · Causes

Why it is happening

  1. 01

    Diesel vehicles

    Diesel engines are a major source of nitrogen dioxide.

  2. 02

    Congestion

    Stop-start traffic increases emissions.

  3. 03

    Wood burning and other sources

    Domestic wood burning and regional sources add particulates.

03 · Impacts

Who and what it affects

  1. 01

    Health effects

    Air pollution contributes to respiratory disease and premature deaths.

  2. 02

    Inequality

    Deprived areas are often more exposed to traffic pollution.

04 · Solutions

Documented approaches

  1. Ultra Low Emission Zone

    A daily charge for vehicles not meeting emissions standards.

    Expected effectReduced roadside NO2 in areas where it applies, per City Hall evaluations.

  2. Cleaner buses and taxis

    Zero-emission buses and cleaner taxi requirements.

    Expected effectReduces emissions on busy corridors.

  3. Walking and cycling investment

    Cycleways and low-traffic neighbourhoods.

    Expected effectSupports low-emission travel.

Explore an illustrative What-If

05 · Key indicators

What can be measured

Policy milestone
London-wide ULEZ2023

Expansion of the Ultra Low Emission Zone to all London boroughs.

06 · Sources

Where this comes from

  1. [1]Ultra Low Emission ZoneTransport for Londontfl.gov.uk(opens in a new tab)
  2. [2]Greater London AuthorityMayor of Londonlondon.gov.uk(opens in a new tab)
  3. [3]WHO global air quality guidelinesWorld Health Organization · Sept 2021who.int(opens in a new tab)

Links open the publishing organisation's site. Some point to the publisher's main page, where the named report or dataset can be found.

Also in London

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