Cleaning London's vehicles

Cities will be at the forefront of tackling air pollution and climate change in the years ahead and solving these twin challenges will mean accelerating the shift to zero emission vehicles.  

Driving a less polluting car or van in the meantime helps reduce London’s toxic air, so we're helping drivers choose cleaner ULEZ-compliant vehicles that meet the latest Euro standards for toxic nitrogen oxides (NOx) in the lab and on the road.

Evidence shows that vehicles often produce more NOx emissions in real-world driving than during compliance testing in labs, especially in dense urban environments such as London.

With our Cleaner Vehicle Checker tools, you can find out which models produce the least amount of NOx in real-world driving scenarios.

What is the ULEZ?

To help improve air quality, an Ultra Low Emission Zone (ULEZ) was launched on 8 April 2019. Most vehicles including cars and vans need to meet tighter exhaust emission standards or pay a daily charge to travel within the zone. 

From 25 October 2021, the ULEZ area will be expanded to include the inner London area bounded by the North and South Circular Roads.  

Check if your current vehicle complies with the ULEZ standards. 

What is NOx?

All combustion processes produce nitrogen oxides (NOx). In London, road transport is the main source of these emissions. However, there are technologies available that can nearly eliminate NOx from engine exhaust before it is released from the tailpipe.

NOx emissions need to be tackled immediately because they are harming the health of Londoners.

NOx is primarily made up of two pollutants - nitric oxide (NO) and nitrogen dioxide (NO2). NO2 is of most concern due to its impact on health. However, NO easily converts to NO2 in the air, so to reduce concentrations of NO2 it is essential to control emissions of NOx. 

These gases are formed and released into the air when fuel is burned at high temperatures, for example by diesel and petrol cars. Evidence shows breathing in high levels of NO2 can inflame the airways in our lungs and, over a long period, affect how well our lungs work. 

Combustion engines also produce emissions of particulate matter (PM) known as primary particulate matter. In addition, NOx can also react with other compounds in the atmosphere to form secondary particulate matter. PM can cause a wide range of health impacts and affect vegetation by reacting to form smog and acid rain. 

What about CO2?

Carbon dioxide (CO2) is a greenhouse gas that contributes to climate change, including extreme weather events, sea level rise, floods and drought. The current EU target for CO2 from new passenger cars is 130g/km, but this will drop to 95 g/km by 2021. Learn more about the CO2 emissions of new and used cars.

Ideally, drivers will choose vehicles that emit low levels of NOx and CO2.

The Mayor's London Environment Strategy includes longer term strategies to tackle CO2 emissions from transport and buildings, all of which will help put London on a path to becoming a zero-carbon city by 2050.


What are Euro standards?

European (Euro) standards set limits on the acceptable amount of harmful air pollutants coming from the exhaust emissions of vehicles sold in the EU.

Before a new vehicle model is approved for sale in Europe, car makers must arrange for emissions tests to show that it meets the current Euro standard. However, results produced in the lab don’t always reflect the emissions produced by vehicles in 'real world' driving scenarios.

The first Euro standard was introduced in 1992. Since then, EU-wide emissions standards have placed ever tighter limits on exhaust emissions. Euro 6 is the current standard in place, but an important upgrade known as Euro 6d began phasing in from late 2017 and will be fully in place by 2021.

Who are we working with?

The Cleaner Vehicle Checker forms part of a wider commitment to work with C40, a network of the world’s megacities committed to addressing climate change, on a global car rating system. 

We're working with Emissions Analytics, the independent vehicle testing company which created the EQUA Index using Portable Emissions Measurement Systems (PEMS) testing.  

Emissions Analytics actively tests new vehicles and will keep ratings for Euro 6 vehicles on the Checker up to date. If a specific model has not been tested, Emissions Analytics can show results for the nearest equivalent model. Find out more about the EQUA Index

We are also working in partnership with the TRUE Initiative, a group of experts and interested parties, including the ICCT (International Council on Clean Transportation) and FIA Foundation, who are working together to improve urban air quality in cities around the world. 

The TRUE Initiative utilises data sources such as the European CONOX database and also carries out roadside emissions testing programmes periodically to obtain real-world emissions of vehicles in use and as they age. Find out more about the TRUE Rating

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