Bath’s Clean Air Zone

Introduced in March 2021, it was the first CAZ outside of London. It was introduced to help the city meet the UK’s air quality standards by reducing nitrogen dioxide (NO₂) concentrations.

Nitrogen dioxide, NO₂, is a gas that mostly comes from cars, buses, and other vehicles – especially older diesel ones. Breathing it in can be bad for your health, especially if you have asthma or other lung problems.

The UK legal limit for nitrogen dioxide is 40 micrograms per cubic metre (40μg/m³), measured as a yearly average², and Bath was mandated by the government to meet this target as quickly as possible.

Now, three years after its launch, the results show that the CAZ is not only meeting these goals but also creating a cleaner, healthier city.

Bath has a class C clean air zone. That means charges do not apply to private cars or motorbikes. Charges only apply to commercial vehicles that do not meet the required emission standards.

This can include:

The levy is designed to deter high polluting vehicles from entering the zone. It provides an incentive to replace polluting vehicles with cleaner ones.

The majority of air pollution is from domestic travel and vehicle emissions¹, especially from older diesel engines². 

29% of B&NES carbon emissions come from transport, with92% of nitrous oxide emissions in B&NES being caused by road traffic emissions.³

The charges and fines paid by drivers go first to the central government, which uses some to help run clean air zones. The rest returns to local councils. Bath and North East Somerset received nearly £10 million as a result between March 2021 and May 2023.⁴

Net proceeds from the CAZ are supporting local reinvestment to sustainable transport and air quality improvement projects. These include cycling routes and contributing to replace or upgrade 938 non-compliant vehicles by the end of 2022.⁵

The proceeds also support the local highways and capital improvements programme which includes upgrades to footpaths, bus stops, cycle schemes and installation of new pedestrian crossings.

Since the introduction of the CAZ, NO₂ levels across Bath have dropped significantly. By the end of 2022:

This success demonstrates that the CAZ is not just limited to its defined boundaries but has a broader impact on improving the city’s air quality.

In 2023, Bath reached a major milestone- all monitored sites in the zone recorded NO₂ levels below the legal limit of 40μg/m³. This is a big improvement from 2019 when ten sites exceeded the limit.⁶

Vehicle compliance has also improved significantly. On average, 496 non-compliant vehicles entered the zone daily, down from 1,742 per day in the zone’s first week.⁷

These results highlight a major shift on Bath’s roads. Older, high-emission vehicles are being replaced by cleaner, low-emission models, helping to improve air quality across the city.

Initially, Wera raised concerns about the scheme’s inclusivity. She worried it could negatively impact people with disabilities and those unable to afford a new, compliant vehicle, leaving them reliant on private transport.

However, financial support from B&NES has helped ease this transition. Over 900 vehicles have been replaced with cleaner alternatives, speeding up Bath’s shift to a more sustainable transport network.⁸

Air pollution is not only an environmental issue but a public health crisis. According to the Royal College of Physicians, over 40,000 premature deaths in the UK each year are attributed to poor air quality.¹⁰

Nitrogen dioxide (NO₂), a key pollutant targeted by the CAZ, has been identified as particularly harmful. It can inflame the airways, cause shortness of breath, and exacerbate pre-existing lung and heart conditions such as asthma and chronic obstructive pulmonary disease (COPD).¹¹

Over the long term, high levels of NO₂ can affect children’s lung development, and there is evidence that children who grow up in highly polluted areas are also at greater risk of developing asthma and other respiratory illnesses.

Moreover, long-term exposure to NO₂ has been linked to an increased risk of heart attacks and dementia. By reducing NO₂ concentrations, Bath’s CAZ is not only improving air quality but also the health of its residents.

In fact across B&NES, around 12,000 people suffer from asthma, with recent research indicating that 74% of new UK cases occur in urban areas¹². Furthermore, Poverty is driving the worst death rates from lung conditions in Europe¹³. To tackle these health inequalities, lung health must be a top priority.

“Not getting on with electrification is a complete dereliction of duty- not just to our net zero plans but to public health”

Wera believes that creating a Clean Air Zone (CAZ) is just one step in tackling air pollution in Bath. She has consistently fought for additional measures to reduce harmful emissions and protect public health.

In 2017-19, Wera presented the Vehicle Emissions (Idling Penalties) Bill 2017-19, aimed at increasing fines for idling vehicles and granting local authorities more power to enforce penalties.

Idling is a major source of unnecessary pollution, yet it can be avoided simply by turning off the engine. Restarting a car after a short stop uses less fuel and produces fewer emissions than idling. Unfortunately, the bill did not pass before the end of the parliamentary session and did not progress further.

Wera has long advocated for comprehensive clean air legislation, pushing for greater powers and funding for local councils to monitor and tackle pollution effectively. She believes residents deserve real-time air quality data, empowering them to make informed choices about their transport and environment.

She also backed the Clean Air (No. 3) Bill¹⁴  which sought to:

Despite its ambitious goals, the bill did not progress through Parliament.

While some of these initiatives have faced setbacks, Wera remains committed to ensuring cleaner air for Bath. She continues to push for policies that reduce emissions, promote sustainable transport, and protect public health.

Working closely with Asthma + Lung UK, Wera is one of the politicians standing up for lung health. She has promised to improve access to diagnosis and care, push for cutting-edge research on new treatments, and champion stronger policies to combat air pollution. ¹⁵

Bath’s Clean Air Zone (CAZ) goes beyond reducing vehicle emissions- it’s also driving a shift toward sustainable transport. The city is promoting cycling, walking, and public transport as cleaner alternatives to car travel.

Proceeds from the CAZ are being reinvested in initiatives like the Scholars Way cycle route and the School Streets pilot scheme, which aims to improve air quality around schools by cutting car use. These projects support a healthier, more sustainable future for Bath.

Wera has been a strong advocate for active travel as a key solution to reducing carbon emissions in the city. She has worked with organisations like Bikeability, Sustrans, and the Two Tunnels Greenway to promote safer, more accessible cycling routes.

The Two Tunnels Route is a scenic 13-mile loop that includes the iconic Devonshire Tunnel, allowing cyclists and walkers to travel easily to Midford, Wellow, Radstock, and beyond. Today, this cherished section of the National Cycle Network serves as a green ribbon through Bath, connecting communities and encouraging sustainable travel.

It connects residents to work, schools, and the beauty of the surrounding countryside. It’s a shining example of the network’s power, with over a quarter of a million journeys made by cyclists and walkers each year.

In 2021, walking, cycling, and wheeling saved the UK economy £36.5 billion by preventing 138,000 serious long-term health conditions and avoiding more than 29,000 early deaths.¹⁷ These figures underscore the importance of continued investment in active travel infrastructure.

The Bath Clean Air Zone (CAZ) is a key part of this broader vision, encouraging sustainable travel choices and supporting a healthier, more active lifestyle for residents. By reducing pollution and promoting cleaner transport options, the CAZ is helping to shape a greener, more connected city.

Wera understands the importance of changing behaviours alongside  implementing measures such as the Clean Air Zone. She regularly meets with representatives from First Bus, WECA and the council to be updated on the status of the city’s public transport systems and ensure that residents’ concerns are heard.

Bath’s Clean Air Zone is a pioneering effort that is yielding positive results. By cutting harmful NO₂ levels, it is improving air quality, protecting public health, and setting an example for other UK cities.

Though the Clean Air Zone (CAZ) has made great progress, more work remains. The Council is also tackling other air pollution sources, such as diesel trains that continue to run through the city. Moving forward, electrifying rail lines will be key to aligning public transport with Bath’s clean air goals.

With ongoing investment in clean air and sustainable transport, Bath is on track to becoming a healthier, more vibrant place to live.

1. UK Government, ‘The Air Quality Standards Regulations 2010’.
2. UK Government, ‘Transport and environment statistics: 2023’, October 2023.
3. Asthma and Lung UK, ‘What effect does air pollution have on your health?’.
4. B&NES, ‘Transport Fast Facts’.
5. B&NES: ‘Measuring our progress’.
6. B&NES, ‘Bath’s Clean Air Zone Annual report summary 2023’.
7. B&NES, ‘Financial support to adapt or replace vehicles’.
8. Wera Hobhouse, ‘Environment Bill’, Hansard, Jan 26, 2021.
9. Royal College of Physicians, ‘Every Breath We Take: The Lifelong Impact of Air Pollution, Report of a working party’, Feb 2016.
10. Asthma and Lung UK, ‘Air pollution effects on your lungs, including lung cancer’, Feb 2023.
11. UK Parliament, ‘Vehicle Emissions (Idling Penalties) Bill’, Jul 2019.
12. UK Parliament, ‘Clean Air (No. 3) Bill’, Oct 2019.
13. Wera Hobhouse, Politics Home: The House, February 2023.
14. Sustrans, ‘Stop active travel funding cuts’.
15. Paul Barltrop, ‘Bath air quality improves since introduction of clean air zone’, BBC News, Aug 25, 2023.
16. Wera Hobhouse, Business of the House, Hansard, Nov 16 2023.