Towards Better Air Quality: Case study of London’s LEZ


Noxious air quality and its long-term effects on human health has been a growing concern for many years now. WHO estimates that outdoor air pollution is responsible for 29% of all deaths and diseases leading to lung cancer. It also has an impact on brain and heart diseases, and on reproductive system (WHO, n.d.). The air pollution is more dangerous for infants, children and the elderly. In London, the inhabitants lives in an area exceeding World Health Organisation guidelines for air quality (TfL, 2019). More than 9000 people die every year in London because of air pollution (GLA, 2017). It has been found that the most deprived areas and the lower-income dwellers were also the most exposed places to air pollution (Kelly, 2011). It shows that tackling the issue of air quality relates to tackling various other linked social issues, such as social inequalities for example.

Air pollution is today characterised by the presence of specific components. The World Health Organisation identified the most harmful pollutants before editing guidelines to limit their concentration. They are:

  • PM for Particulate Matters, categorised by the size of the particle (PM10 is particles with a diameter of less than ten micrometres (μm)).
  • NO2
  • Ozone and sulfure dioxide

London is mostly concerned by the PM and NO2 pollutants (GLA, 2017) (AEA, 2003) where the road transportation has a major role to play. Half of the NO2, PM2,5 and PM10 emissions are produced by the vehicles on the roads in greater London (GLA, 2017). In 2008, the city had the worst outdoor air quality in UK and one of the worst of Europe (TfL, 2008). Moreover, the authorities always had the obligation to work towards EU quality norms whose first policies on the subject were launched in 2005 (European Commission, 2017).

Since the 2000’s, the number of Low Emission Zones (LEZ) initiatives in Europe has increased, with leading cities in Sweden and Italy. In September 2017, there were 227 LEZ in 12 countries in Europe (Ademe, 2018). The principle idea is to tackle the traffic congestion on roads and performance of the vehicles. These two factors are responsible for a greater part of the air pollution in our congested and dense cities. On similar lines, the London city hall decided to implement a Low Emission Zone (LEZ) as the key action to tackle its issue of rising air pollution. The LEZ enforces exclusion of the polluting vehicles from a zone including the city. Through the interventions, emissions are projected to consequently reduce and incite people and companies to buy modern and cleaner vehicles. This article explores the case study of the LEZ in London and looks into their interventions and regulations taken by the authorities to regulate the issue of increasing air pollution in London.

The London Low Emission Zone

The analysis of London’s air quality in 2003 showed that emissions were already decreasing due to better performing new vehicles. The objective was to accelerate this trend in order to reach WHO’s guidelines faster, and to ensure every area in Greater London achieve it (AEA, 2003). To do so, the Low Emission Zone was introduced in 2008. Two policies were to be implemented through the LEZ:

  • decrease in the number of vehicles on the road
  • modernisation of the fleet in order to reduce individual emissions.

The proposal for a Low Emission Zone came directly from the Mayor Transport Strategy and the Mayor of London in 2006 (Wilson, 2006). The scheme is now managed by Transport for London (TfL). Moreover, the London Local Air Quality Management (LLAQM) agency was created in 2016. It monitors air quality in each borough in the capital. Their role is to declare the places exceeding limit values, ensure an Action Plan is in place and updated, and annually report the monitoring.


In 2008, the data below gives an idea of the situation before the implementation of the LEZ. All indicators are above the WHO limits. The objectives of the London LEZ are as following (GLA, 2017):

  • Reduce exposure at priority locations such as schools, and tackling inequalities.
  • Compliance with UK and EU limits concerning air pollutants.
  • Reach WHO guidelines by 2030. These are more ambitious than EU limits because they concentrate solely on the health issues and do not emphasise on the environmental aspects.

Source London : (Wood, 2015)
In all the data analysis, figures are expressed in annual mean concentration (μg/m3) rather than in emissions (tonnes) because the aim is to evaluate the impact on population’s health. To compare data from different sources, the best choice is the annual mean concentration. There are 2 figures for the data for London. The first correspond to a background measurement station (Bk), and the second from a railway station (RS), far more exposed.


Figure 1 – Boundaries of the London Low Emission Zone

The LEZ covers all local roads in Greater London, Heathrow airport and parts of the M1 and M4 motorways (Ellison, 2013). It operates at all times of the year and cars and motorcycles are not included in the scheme. There are 3 main interventions taken under the LEZ:

Euro Norms for Vehicles Performances

The criteria of vehicle compliance are based on Euro norms, or European Emission Standards. These are labels characterizing a vehicle’s emissions of PM and NOx. The higher the number, the more restrictive the norm. A small synopsis has been explained in figure 2. The implementation of the LEZ follows 4 stages. This incremental process attempts to reach the initial goal without generating a crisis for the vehicle users because of restrictions.

Figure 2 – The 4 stages of the Euro norms

It was noted that the London LEZ has a national impact as a large proportion of the national fleet comes to London at any given time (AEA, 2003). The indicators are fixed in a way to find a balance between costs to industry and the impact on air quality. A last Stage 5 was added to reach Euro IV norm for NOx for the bus fleet of London. The main objective is to become the first zero-emission bus fleet in Europe.

Surveillance and Economic System

In order to control the access to the LEZ, TfL installed a CCTV surveillance system at multiple locations in London. Fixed or mobile cameras can read license plates and create a database of the violators. This information is then compared to the database from different organisations that identifies each vehicle in Great Britain. TfL reported a acceptance rate of over 95% for every phase of the implementation (Ademe, 2018). In 2008, It was predicted that this monitoring system would cost ₤50 million and each year, the running costs would be ₤80million. It was also predicted that the system would also yield ₤5 to ₤7 million through fines and entry taxes (TfL, 2008). Users can pay to enter the LEZ with a non-compliant vehicle, providing a daily fee from £100 to £200. Infractions are punished by a fine from £500 to £1000.

Congestion Charge Zone

The municipality also settled a Congestion Charge zone in 2003 to enter in the central London area. It operates from 7am to 6pm during weekdays. Every vehicle, except motorbikes, disabled drivers, electric vehicles and collective transport, is affected and must pay a £11.5 daily fee to drive within the zone. The objective is to reduce congestion and pollution in this area. In comparison with the previous year, the traffic reduced by 27% and cycling in the area increased by 66%. Moreover, all the net revenue is spent on improvements of public transport across London (TfL, 2019). The objective is to favour a switch to public transport, well-developed in this area.

Other Policies Promoting Better Air Quality

The LEZ has significant impacts on the air quality in London. However, it is not sufficient and is integrated with various other policies. Recently, London implemented the first Ultra-Low Emission Zone (ULEZ) of the world in the central area of London. It replaces the former T-charge (toxicity charge), and will operate within the same boundaries at all times of the day. In this area each vehicle are required to be of specific norms. The standards are:

  • Euro 3 for two-wheeled
  • Euro 4 for petrol carsƒƒ
  • Euro 6 for diesel cars
  • Euro VI for heavy vehicles.

The vehicles not meeting the emission standards will have to pay £12.5 for light vehicles, and £100 for heavy vehicles. This fee is in addition to the congestion charge that operates in the same area. Its boundaries are proposed to be extended in October 2021 to the northern and southern circular roads of London (TfL, 2019).

Since 2008, many other initiatives have also emerged. Transport for London launched a Freight Quality Partnership to set up a dialogue with freight industry, local governments and environmental groups. Good construction logistic practices, cleaner technologies and night-time deliveries are some of their projects to limit the impact of freight delivery on air quality (AQAP, 2008).

The Energy Master Plan of London also plays a role in air pollution reduction. An important part of emissions is due to residential heating and the use of bad quality fuels, for example 37% of NOx emissions (GLA, 2017). Implementing and promoting a decentralised energy network tackles part of the issue. Here, the local authorities provide heat and power demand locally and can therefore control the origin of this energy by privileging cleaner energy production systems (GLA, 2017). This is also a way to regain a local control on the polluting sector. This contribution is vital as a great part of London’s air pollution comes from its outer borders (Walton, 2015).

This last observation underlines the necessity of collaborations for national and European policies to tackle air quality issues. London authorities relies on data and information provided by the Convention on Long-Range Transboundary Air Pollution adopted in 1979. It has been ratified by most countries of Europe and North America and identifies specific measures to be taken by parties
to cut their emissions (UNECE, 2018).

Evolution and Impacts

The graphs below present the decrease in concentrations of pollutants in the air after 8 years of implementation. There is a considerable reduction due to the direct impact of the LEZ policy. However, we can qualify this assessment by looking more closely at the different graphs. The WHO objectives in roadside or inner London is yet to be achieved and there hasn’t been any significant changes in the levels of PM2.5. The most polluted areas still lack in providing proper quality of life to inhabitants. This amelioration might not be only due to the LEZ implementation. Many factors have to be taken into account, however we can reasonably think that the impact on road transport has been significant.

Figure 3 – Trends in NO2 in London – 2000 to 2016

Figure 4 – Trends in PM2,5 in London – 2004 to 2016

Figure 5 – Trends in PM10 in London – 2004 to 2016


Air pollution in India is a major crisis and needs immediate attention. A similar intervention or other innovative solutions can help in significantly reducing traffic and concentration in pollutants. However, the context in Indian cities is completely different than in London, and this solution must be studied before any implementation in order to adapt it to the local situation.

The experience of the Low Emission Zone in London shows that city-scaled pragmatic action lead to concrete results. However, a LEZ alone is not sufficient to reach the WHO’s requirements. Many efforts still must be done on other sectors such as industries, housing or non-road transport. Moreover, it is important to note that improving the air quality and reducing the pollution is a global concern. The upcoming challenge is to gather these various ambitions into collective action from the cities, the governments and the international agencies.