Improving air quality by means of clear zones

Basic Information

Mobility solution ID






Comprehensive air quality assessments were undertaken in order to designate clear zones in sensitive locations.

Implementing sustainable mobility

Restricted-access clear zones have been shown to result in reductions in localised air pollution. The aim of this measure was therefore to create and validate an air quality model and to assess the environmental impacts of different vehicle types in order to designate clear zones in sensitive urban locations.



Activities included:

  • collecting baseline data on safety, environment, economics and accessibility;
  • presenting the collected data graphically in order to raise awareness of air quality issues and the need for clear zones; and
  • proposing clear zone and access management strategies based on an analysis of the data.

A simple screening air model was constructed, encompassing significant roads and interchanges. Monitoring and data collection were then carried out on the road network. In early 2008, the Adelphi clear zone was completed and a city centre clear zone was also created.


Emissions and predicted air quality were analysed, and during the CIVITAS SUCCESS evaluation period the trend in air quality was one of general improvement, with concentrations of all pollutants seen to be decreasing. However, this decrease cannot be clearly and directly attributed to the measures within CIVITAS SUCCESS, as these were relatively small-scale demonstration projects and the impacts are not easily separated from other changes taking place in the city, such as changes in land use and reductions in emissions resulting from improvements in vehicle technology.

This fact sheet has been updated by a third party on the basis of available information (not by the city itself), therefore we do not guarantee any data with respect to their content, completeness or up-to-dateness.

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