Air quality continues to improve across Bath and North East Somerset

A continued decline in nitrogen dioxide concentrations and ongoing improvements in air quality across Bath and North East Somerset are evidenced in two new reports that were published on 26th August. 

The Bath Clean Air Zone (CAZ) Annual Report 2024 compares 2024 data with the 2019, pre-Covid pandemic baseline and shows average nitrogen dioxide (NO₂₎ concentrations in the Clean Air Zone are 40% lower, equivalent to a reduction of 13 micrograms per cubic metre (μg/m³).

The second of the reports, the Air Quality Annual Status Report 2025, reviews and assesses air quality data for Bath and North East Somerset in 2024 and shows all continuous analyser monitoring results were below the annual average objective of 40 µg/m³ for NO₂ and particulate matter under 10 micrometres (PM₁₀).

The CAZ report highlights several key findings that demonstrate the air quality improvements across B&NES, including:

• In 2024, no monitoring sites within the CAZ recorded an annual average NO₂ concentration greater than 36 μg/m³, 21 fewer sites when compared to 2019.
• Average NO₂ concentrations for 2024 in the Bath urban area, outside the zone are 41% lower than in 2019, a reduction of 10.4μg/m^3.
• Compliance has also improved with an average of 275 non-compliant vehicles seen in the zone each day, compared with 1,742 per day during the launch week of the CAZ in March 2021.

Net proceeds from the CAZ are supporting local reinvestment to sustainable transport projects or schemes which complement wider air quality improvements.

The Air Quality Annual Status Report 2025 gathers data from 167 NO₂ diffusion tube sites and three continuous NO₂ analysers, with an additional three particulate matter analysers.

Although these results were below the annual average objective, there were four exceedances of the 24-hour mean objective for PM₁₀ at Windsor Bridge in Bath due to nearby construction work, however this still remains within the allowed limit of 35 exceedances per year.

Monitoring results for particulate matter under 2.5 micrometres (PM_2.5) were under the annual average objective of 20 µg/m³.

Councillor Sarah Warren, Deputy Leader and Cabinet Member for Sustainable B&NES, said: “It is encouraging to see the statistics from both reports show a continued decline in air pollution, resulting in cleaner air and a positive impact on the health of our residents and visitors.

“Notably, the CAZ Annual Report 2024 shows the CAZ is working to improve air quality outside of the zone as well as within it, and that 949 polluting vehicles have been replaced under our financial assistance scheme. This is good news for all of us visiting, living and working in Bath and North East Somerset.

“Whilst these reports are extremely positive, there is no evidence of a safe level of exposure to NO₂ concentrations and particulate matter, so we will continue to closely monitor air quality and benchmark our compliance rates.

“Residents and visitors who wish to help reduce pollution may choose to walk, wheel or cycle short trips, or consider whether public transport is an option for their journey. Other helpful actions include car sharing, consolidating home deliveries, and saving vehicle journeys for trips where there is no viable alternative for you.”

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.