Bath’s Clean Air Zone (CAZ) is continuing to improve air quality with a decreasing trend in nitrogen dioxide concentrations across the city, new data published today shows (August 24).
The 2022 Annual CAZ report published by Bath & North East Somerset Council notes that compared with 2019, there has been a 26% reduction in annual mean nitrogen dioxide (NO2) within the zone, representing an average reduction of 8.5 micrograms per cubic metre (μg/m3).
In the urban area outside the zone, there has been a 27% reduction in annual mean NO2 concentrations (an average reduction of 7.1 μg/m3) with nine fewer sites exceeding the legal limit of 40 μg/m3 falling from 10 sites in 2019 to one site in 2022.
The figures also indicate an additional reduction of 6% in annual mean NO2 concentrations in 2022 compared with 2021, as well as a reduction of 7% within the CAZ boundary.
This data indicates air quality has improved both within the CAZ and the areas which immediately surround it, with indications, too, of improvements to air quality across the wider B&NES area as well.
Compliance has also significantly improved with 71% fewer polluting vehicles driving in the zone by the end of December 2022 – an average of 497 vehicles per day – compared with an average of 1,742 vehicles in the first week the CAZ launched in March 2021.
The report also notes the impacts of Covid-19 and the partial closure of Cleveland Bridge from October 2021 to October 2022 on the volume and direction of traffic through the city, meaning that clear conclusions on traffic displacement in 2022 cannot be drawn. The council has submitted its air quality data to the government’s Joint Air Quality Unit (JAQU) which is due to publish a progress report later this year.
The council has also recently published its Air Quality Annual Status report for 2023 which shows that from NO2 monitoring at four continuous analysers in 2022, all results were below the annual average objective. There was one exceedance of the 1-hour objective at the Bath A4 site, however, 18 exceedances are allowed.
The council’s £9.4m financial assistance scheme to help local businesses and individuals replace or upgrade polluting vehicles with cleaner, compliant ones saw owners of more than 1,500 vehicles apply for support. 938 polluting vehicles were replaced or upgraded through the scheme by the end of 2022.
Bath’s CAZ was launched on 15 March 2021 to urgently tackle harmful levels of air pollution caused by the most polluting taxis, vans, buses and larger commercial vehicles regularly driving in the city.
It was the first to be launched outside London and works to reduce pollution in Bath by levying a £9 or £100 a day charge on anyone driving a chargeable higher emission vehicle in the zone. This excludes private cars and motorcycles which are not charged.
The charges are designed to deter higher polluting vehicles from entering the zone, while also speeding up the natural replacement rate of polluting vehicles in exchange for cleaner ones. Any revenue over and above the operating cost will be spent on supporting sustainable transport projects or schemes which contribute towards improvements to air quality.