How effective is Bath’s Clean Air Zone strategy?

Sustainable Leaders | Europe

By Julia Riopelle, Co-Editor in Chief

Published July 3rd, 2021

Since March 15th 2021, Bath, United Kingdom, has begun to fine highly polluting vehicles driving within their ‘Clean Air Zone’ in an effort to bring the city’s atmospheric nitrogen dioxide levels below the legal limit.

The legal limit for atmospheric nitrogen dioxide concentrations in the UK is 40 micrograms per meter-cubed. Nitrogen dioxide frequently reaches high concentrations in polluted areas and can be harmful towards human health; causing inflammation of airways, coughs, shortness of breath, worsening of lung and heart conditions and more. According to the UK government, nitrogen dioxide pollution contributes to nearly 36,000 deaths in the UK annually.

Nitrogen oxide plays multiple roles in the chemical reactions of polluted air. One third of these molecules are estimated to be emitted into the atmosphere via combustion reactions in the engines of motor vehicles. This is particularly an issue in densely populated cities which experience a lot of traffic and the stalling of car engines.

Bath, Somerset, United Kingdom. | Silviya Noneva / Unsplash

Many areas in Bath have exceeded this permitted limit. By installing air monitors on signs and lamp posts on the side of streets, the city has been able to measure its air quality over the past years. In 2014 the average annual nitrogen dioxide levels reached 44 micrograms per meter-cubed, whilst in 2019 they were recorded at an annual average of 29 micrograms per meter-cubed. Bath and North East Somerset were advised by the government to continue these decreasing trends by implementing the Bath Clean Air Zone.

The Bath Clean Air Zone operates under the following rules. Coaches, Buses, trucks, lorries and private heavy goods vehicles, all using either Euro 1-5/V diesel and Euro 1 to 3 petrol, have to pay a daily charge of £100 within the Clean Air Zone. Taxis and private car hire, minibuses, vans and light goods vehicles using Euro 1-5/V diesel and Euro 1-3 petrol are charged daily £9 in the Clean Air Zone.

Those who have outstanding charges or have been fined have 28 days to pay, however fines can be reduced from £120 to £40 if paid within the first 14 days. Private cars and motorcycles, even those which are used for work purposes, are not charged.

Three months into the Clean Air Zone being implemented, nitrogen dioxide levels have still been hovering between 22 micrograms per meter-cubed and 49 micrograms per meter-cube at peak traffic hours between 2pm to 10pm, when measured from the 26th of June 2021 to 3rd of July 2021 (data taken from Bath and North East Somerset Council website). Since COVID-19 measures have eased in the UK and shops have reopened, Bath parking lots which stood empty for months are now full every day and the streets are bustling with eager shoppers.

7-day hourly measurement of nitrogen dioxide, nitric oxide and nitrogen oxide at Bath A4 roadside. Measurements from 26 June 2021 to 3 July 2021, three and a half months after Bath Clean Air Zone was implemented. | Bath and North East Somerset Council

Looking at the recent trends, it still seems like Bath is reaching high nitrogen dioxide levels during their rush hours. However, daily fluctuations could still even out to an annual average which is below the 40 micrograms per meter-cubed limit. This can only be estimated with time and accurate predictions.

By choosing Class C Charges strategy, the city opted for the option that would allow as many cars as possible to be exempt from the rule, whilst still averaging below the legal maximum concentration. However, one can also argue that Bath and North East Somerset Council are applying charges to the wrong vehicles.

The fact that private cars and motorcycles are exempt from the rule, still allows for a massive proportion—probably even the majority—of nitrogen dioxide producing vehicles to be unaccounted for. To combat pollution, it seems more logical to promote the reliance on public transport, in order to transport more people for less emitted nitrogen dioxide in the long term. However, buses and coaches are amongst the vehicles which are charged £100 daily.

Private cars (unless electric) should be the vehicles which are charged more, in order to increase incentive for the public to use public transport. In return, public transport prices can be significantly reduced, as the demand for these services increases. Bath Council could even use the revenue generated from the Clean Air Zone charges and fines, to invest into public transport infrastructure, in order to make it an economically viable option for everyone.

Map of Bath Clean Air Zone. | United Kingdom Government Website

Local businesses which rely on motor vehicles (i.e., vans, lorries, light good vehicles) for transport of materials, should either be charged less or be exempt from the rule. Whilst non-local businesses should still pay the £100 charge for day visits. Additionally, elders and individuals with disabilities or should also be exempt from the Clean Air Zone charges and allowed to drive private vehicles in the city.

Many studies and some cities, such as Hamburg, Oslo and even Paris, have proposed plans to become either fully or partly car free. For such large cities, these plans include either having regions of the city that ban private cars or having ‘car-free’ days. Making cities car-free and increasing pedestrianization, can decrease air pollution, noise pollution and temperature. It would also allow for the opportunity to increase green spaces in cities, promoting both pollinator biodiversity and human mental health.

Bath is a very small and historic city, and for the majority of the able public everything can easily be reached within a walking distance. Thus, in theory, the Clean Air Zone can be significantly expanded towards the outer suburbs. If metropolises are speaking of measures to decrease traffic, a small city like Bath has the potential to be car-free.

Visiting cars (ie. non-Bath residents) should park in parking lots on the outskirts of the small city, and then either walk or have cheap public transport connections towards the city centre. Visiting businesses or private vehicles which need to enter the Clean Air Zone should pay the full charge. Once again, both Bath and non-Bath disabled residents should be exempt from any charge.

‘Bath has the potential to be a car-free city.’

Implementing measures to make cities car-free could enact huge strides in decreasing air pollution. It could shift the reliance on cars for only journeys between cities and the reliance on public transport within cities. Though this may seem inconvenient at first, humans are very adaptable—if a century ago we did not use cars, then we can readjust old habits and take the bus.

If Bath and North Somerset Council really wants to decrease air pollution and improve human health, stricter measures need to be implemented. The Clean Air Zone is a good start, though not enough. By investing revenues from the charges and fines, as well as government funds, into public transport infrastructure, one would allow for better connections, environmentally friendly buses, cheaper fares, more efficient schedules and better paid employees.

It is time cities and its people start making sacrifices in their habits—as many of them are not necessities. The environment and all other of its inhabitants have made involuntary sacrifices for humans; it is time we do better. The UK has the money and the technology to make its cities greener, by creating solutions which keeps everybody in mind.

If you live in Bath or are planning a trip, you can check here if your motor vehicle is exempt from the current charges.

Featured Image: Alex Atudosie | Unsplash

DEFRA (2021) ‘Graph of hourly measurements for Bath A4 roadside.’ UK Air Information Resource. Department for Environment, Food and Rural Affairs. Available at: [Accessed April 6th 2021]

GOV.UK (2021) ‘Drive in a clean air zone.’ Government United Kingdom. Available at: [Accessed April 6th 2021]

Lenner M. (1967) Nitrogen dioxide in exhaust emissions from motor vehicles. Atmospheric Environment. Volume 21, issue 1, pages 37-43.

Nieuwenhuijsen M. and Khreis H. (2016) Car free cities: Pathway to healthy urban living. Environment International. Volume 94, pages 251-262.

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