Impact of Low Emission Zones laid bare in new review

The Clean Cities Campaign has published research into the benefits of congestion and air pollution mitigation schemes across Europe, and issued an open letter to EU leaders ahead of major new policy changes.

The impact of Low Emission Zones (LEZs) and Ultra-Low Emission Zones has been revealed in a new review by a leading campaign group. 

The Clean Cities Campaign investigation points to an average reduction in nitrogen dioxide (NO2) emissions of around 20% in LEZ areas, defined as those where the most polluting vehicles are subject to restrictions on access. This rises to 44% for central London since the Ultra-Low Emission Zone expanded three years ago. 

Elsewhere, NO2 had was down by 43% in Bath, 33% in Brussels, and 24% in Paris. Using the example of Lisbon, where an LEZ has led to a fall in NO2 of 22% and a PM2.5 reduction of 29%, the report – which can be downloaded here – explains that similar levels were recorded at monitoring stations outside the boundaries of the scheme in Portugal’s capital, suggesting benefits of schemes extend beyond the geographical area the officially cover. 

This idea is supported by a growing understanding that ambient air pollution is not static and moves by nature. As such, major sources of atmospheric pollutants can impact locations thousands of miles away, so it stands to reason that a significant fall in pollution levels in one place might also lead to a drop in neighbouring areas. 

Zero Emission Zones (ZEZs) were also featured in the report, although due to the small number and their comparative infancy, this section is based on predictions. Oxford, UK and Amsterdam, Netherlands, forecast up to 97% less nitrous dioxide (NOx) and a 50% fall in particulate matter emissions through ZEZs. 

The Clean Cities Campaign published the findings ahead of the EU unveiling new proposals to update its Ambient Air Quality Directive on 26th October. Despite growing evidence in support of LEZs, not to mention a rapidly increasing number of these schemes going live across Europe, Brussels has not included zones in its official Impact Assessment. Campaigners believe this is a huge missed opportunity. 

‘The update of the EU clean air laws is a once-in-a-generation opportunity to decisively cut toxic air pollution across the continent. Our research confirms Low Emission Zones work, and are already used in 320 European cities. We call on EU legislators to take this strong evidence into account when they set air pollution limits. This is the only way to avoid the grave health impacts of air pollution as well as the hundreds of thousands of premature deaths each year,’ said Barbara Stoll, Director of the Clean Cities Campaign.

An open letter – signed by Clean Cities Campaign, Transport & Environment, HEAL (Health and Environment Alliance), C40 Cities, and European Cyclists’ Federation – has been issued to European policymakers calling for the following: 

*Full alignment of EU limits with global air quality guidelines set by the World Health Organisation with requirement to comply by 2030

*Increase in roll out of reliable, consistent air quality monitoring infrastructure 


Image: Musa Haef






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1 year ago

Sounds great. Thank you. But if the same number of polluting vehicles are still around somewhere in those cities (and in areas just beyond which is also good news) where on earth does all the NO2 end up instead? Or does it mean that there are fewer diesels on the city roads in general now? Or does the NO2 somehow disperse more easily when it is emtted on streets well away from the ZEZ zones? I am puzzled.

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