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Has the ULEZ Zone Worked?

High levels of pollution tend to plague major cities like the capital. In recent years, the problem became so acute in the UK that politicians took drastic action, and this led to the introduction of the Ultra Low Emission Zone in Central London. Yet do such Draconian measures work, and has the government analysed enough data to determine if the ULEZ zone expansion is warranted?

What is ULEZ?

In April 2019, the Mayor of London introduced the ULEZ zone in an area already covered by the existing Congestion Charge. However, motorists would have to pay the new fee 24 hours per day and seven days per week, unlike the current program that only operates between 7 AM and 10 PM.

Vehicles would now have to meet stringent emission standards to drive within the new ULEZ charge zone and would have to pay the fee every time. They face a punitive fine if they fail to either pay in advance or soon after their journey.

Who Is Affected?

Vehicles are assessed based on their emissions levels and compliance with Euro standards.

  • Cars and vans fitted with a petrol engine must meet Euro 4 standards,

  • cars and vans with a diesel engine must meet Euro 6 standards,

  • lorries and buses must meet Euro VI standards,

  • motorbikes must meet Euro 3 standards.

In practice, most modern petrol-engined vehicles will be exempt, but the diesel standards are more rigorous, and only the very latest models will likely be unaffected.

Certain historic vehicles are exempt, as are fully electric cars, but vehicles that do not meet the standards will need to pay £12.50 (small vans, cars and motorcycles) or £100 (buses, coaches and lorries).

Assessing the Impacts

The primary goal of the programme was to reduce the number of polluting vehicles within the zone. By doing so, regulators felt that they could cut down on the level of emissions and improve the air quality. As a side benefit, they also aim to improve traffic flow in this heavily congested area.

Air Quality

You can find air quality monitoring stations throughout central London. Scientists gather the data and build a model to analyse concentrations across the city.

Vehicle Movement

A network of cameras operates around the clock to detect vehicle movement in the zone. The government can then report the daily number of unique vehicles entering or operating within the zone.


Government regulators commissioned a report to determine whether the ULEZ zone in London had made any difference. They were able to use information gathered before its introduction and based on the "T" charge that came into force in 2017. That programme was far less stringent, and politicians subsequently replaced it with the Ultra Low Emission Zone, but it did provide data to help with analysis.

  1. Following the first six months of operation, the report found a significant reduction in the concentration of NO2 at the roadside. This concentration had dropped by 36% over a period which began in February 2017 and ended in September 2019.

  2. NOx emissions from vehicles in the central zone had been reduced by some 200 tonnes, or 31% during the initial six months of zone operation. Regulators reported that this was ahead of schedule, based on their expectations for the first year of operation.

  3. Carbon dioxide emissions have been reduced by 9,800 tonnes (or 4%) compared to a scenario without the zone. This level was 30% lower than in 2016.

  4. Traffic flow within central London may have reduced by between 3 and 9% over the first six months, compared to 2018. However, analysts believe that it is too soon to attribute any change solely to the introduction of the zone, and will need to gather a lot more data over a much longer period before they can be sure.

  5. Fundamentally, there was a large decrease in the number of non-compliant vehicles within the central zone during congestion charging hours.

Regulators believe that the scheme encouraged a large number of people to trade in their older, non-compliant vehicles to avoid the charge. Between 2017 and September 2019 reports show a 65% drop in the number of non-compliant vehicles within the zone on an average day. The figures also show an 89% uptake in the number of compliant vehicles within the zone, between February 2017 and September 2019.

Of course, politicians want to raise money from the scheme and to prompt people to pay the necessary fee, should they drive a non-compliant vehicle into the zone. Reports show that following six months of operation, an average of 77% did comply in any 24 hours, with 74% in compliance during the hours covered by the Congestion Charge. These figures were up from the 61% reported during congestion charging hours at the beginning of the scheme.

Expansion of the Zone

On October 25 2021, the boundary of the ULEZ zone expands to include all of inner London. Its border will be the North and South Circular Roads, although those particular roads are not included in the actual scheme.

This expansion will affect a much larger number of drivers and for many, will be their first introduction to the concept. After all, many people may have purposefully avoided central London due to not just the new ULEZ charge zone but also the existing Congestion Charge.

ULEZ Zone Check - How to Avoid the Area

TfL has a handy tool to help motorists determine whether their journey enters the zone or not. This page may help individual drivers modify their route so that they can avoid driving within the zone if possible.

In Summary

If you are one of the tens of thousands of drivers likely to be affected by the ULEZ zone and its expansion, you may want to take action. Certain residents may be able to take advantage of a government incentive to upgrade to a newer, compliant model and can find further information here.