Bristol Clean Air Zone – 3-year Review

The Bristol Clean Air Zone (CAZ) has been operational since November 2022. Directed by the UK Government, it was introduced by Bristol City Council to achieve compliance with air quality objectives in the shortest possible time. Road traffic emissions, particularly from diesel vehicles, are the primary source of urban air pollution. The CAZ therefore incentivises higher-emission vehicles to avoid the city centre by charging older vehicles based on their Euro emission classification. With over three years of operation and two full years of monitoring data now available, it is possible to review the progress achieved.

Review of recent monitoring data shows clear improvements. Average annual mean nitrogen dioxide (NO₂) concentrations reduced by 18% inside the CAZ in 2023 compared to 2022, while the wider council monitoring area saw a 12% reduction. During the second year of implementation, improvements continued but at a slower rate, with reductions of 5% within the CAZ and 4% elsewhere.

The number of monitoring locations exceeding the annual mean objective of 40µg/m³ fell from 24 in 2022 to seven in 2023, and further to five in 2024. Remaining exceedances in 2024 occurred at Colston Avenue, Rupert Street, College Green and the A4044 Temple Way.

Overall, the CAZ has significantly contributed to reducing NO₂ concentrations within the city centre, although progress has slowed during the second year of operation and full compliance has not yet been achieved. The council continues to review potential additional measures to achieve compliance across the entire city. Options under discussion include increasing CAZ charges and restricting through-traffic on Park Street.

Redmore look forward to further improvements in air quality and will continue supporting this by assessing potential air quality impacts in developments.

If you have an enquiry or requirements for Air Quality Assessments or monitoring, please do not hesitate to get in touch with our specialist team today to find out how we can help you.