Clean air zones are being introduced across England to create spaces for cleaner, healthier air.

The work of Bath & North East Somerset Council [1] serves as a useful case study to understand how councils can identify opportunities for Clean Air Zones (CAZ) and how they can be introduced to the community.

Bath & North East Somerset Council outlined the risks associated with air pollution. Poor air quality is harmful to the most vulnerable of residents including children, the elderly and those already unwell.

The main polluting substance that is targeted when creating CAZ’s is nitrogen dioxide (NO2).

High levels of NO2 can cause:

  • Inflammation of the airways, coughing and shortness of breath (short-term exposure)
  • Worsening of existing lung or heart conditions, including asthma, emphysema and bronchitis
  • Increased susceptibility to allergens and respiratory infections

In the long term, high levels of NOcan affect children’s lung development, and there is evidence that children who grow up in highly polluted areas are more likely to develop asthma.

According to Bath & North East Somerset Council, Nitrogen Oxide pollution is thought to contribute to as many as 36,000 early deaths in the UK each year.

Bath’s Clean Air Zone

It was detected that Bath has regularly exceeded the legal limits for Nitrogen Dioxide (NO2). These levels are predicted to continue until 2025 if there is no intervention.

Bath & North East Somerset Council was placed under Ministerial Direction to achieve compliance with the legal limit value for NO2, as quickly as possible, by the end of 2021 at the latest.

The government is providing the council with all the funds it needs to do this, and the Joint Air Quality Unit (JAQU) is independently verifying all of the work being done to meet the new targets.

A Full Business Case was approved in January 2020 and the scheme was launched on 15 March 2021. It is the first charging Clean Air Zone scheme outside of London.

Technical work and research by the council have shown that a charging zone for traffic is the only measure that can achieve compliance. This effectively deters the majority of higher emission vehicles from driving in the inner-city area by fining them for driving within the CAZ.

Higher emission HGV’s, buses and coaches are charged £100 for entering the zone within a 24-hour period; in the same way, LGV’s and taxis are charged £9. Private cars and motorcycles are not charged for entering this area.

The zone is categorised as a Class C Charging Clean Air Zone with traffic management at Queen Square. Managing traffic in Queen Square is a necessary compromise to enable the council to avoid charging private cars.

It also helps to moderate traffic flow to other parts of the city, where emissions would rise to unacceptable levels if large queues were allowed to form.

Evolution of the Bath Clean Air Zone Boundary

Bath & North East Somerset Council have shared how the boundary of the Clean Air Zone has evolved over the project planning period.

The Strategic Outline Business Case Stage – April 2018 can be seen below on the left and the Full Business Case Stage that was published in January 2020 can be seen on the right:

The council had to consider the economic and social consequences of drawing boundaries. They needed to ensure that people did not feel displaced and that their city did not feel too disrupted not only by the development of the CAZ.

Residents and businesses offered comments which were considered by the council in the planning process.

Clean Air Zone Mitigations and Abatement

The council had to consider ways to mitigate the potential negative impacts of the Clean Air Zone.

An extensive mitigation programme has been developed in response to concerns. Highlights of this programme include:

  • A bus upgrade programme with a view to achieving a fully compliant scheduled bus fleet operating in Bath. From the modelling of the CAZ it can be seen that this is crucial to achieving compliance
  • A financial assistance scheme providing grants and interest free loans to businesses, individuals, and community groups to upgrade non-compliant vehicles. This is supported by government funding
  • A package of exemptions that support vital services, disadvantaged groups, and those with hard-to-replace vehicles, along with a means-tested general exemption as part of the financial assistance scheme

Pandemic Impacts

Traffic levels fell by around 70% during lockdown periods, however, they are now returning close to pre-pandemic levels.

NO2  concentrations at the continuous analyser locations in Bath only fell by around 20% during the lockdown and have now risen, being close to levels that could be expected pre-pandemic times.

New vehicle registrations are down which is suppressing natural fleet upgrade rates. There are delays in supplying new vehicles, particularly vans.

Some businesses temporarily closed during the lockdowns which have made engagement with the scheme more challenging.

Following the Launch

On average 32,000 vehicles travel in the Clean Air Zone each day (not including locally exempt vehicles) with diesel LGV’s representing the largest category of non-compliant, fineable vehicles.

There was an overwhelming response to the financial assistance scheme in the run-up to the launch, with around 1,250 applications being processed.

124 vehicles have so far been upgraded and another 344 have passed initial eligibility checks.

Since the launch 10,000 Clean Air Zone Penalty Charge Notices have been issued and 20,000 zone entry charges have been paid.

The press coverage around the launch was largely positive, with Air Quality News [2] describing it as:

“A monumental moment, not just for Bath, but for air pollution up and down the country”

Despite all of the preparation and consultations, some residents were unaware and unprepared for the change in the community and needed ongoing support as part of the behaviour change process.

The financial assistance scheme has been a key element of delivering a successful launch and provides additional air quality benefits through incentivising people to work alongside the enforcement team.

Bath & North East Somerset Council state that after 2 months, the general impression is that the scheme had become business as usual for the public and acceptance was reached.

Key Successes

Key successes of the Clean Air Zone scheme included:

  • A collaborative working partnership with JAQU to resolve problems and to enable delivery of the scheme at pace, as well as an innovative financial assistance scheme using a framework agreement
  • An approach to public consultation that helped to deal with issues and move the public to broad acceptance of change
  • Use of market research to reach over 8000 businesses prior to the launch

Next Steps…

While the council are not currently charging private cars, they are looking at lots of ways to improve walking, cycling and public transport to encourage more people to choose more sustainable ways of getting around. 

The council asks that all drivers consider whether or not they need to take their vehicle and to consider walking, cycling or taking public transport instead, especially for shorter cross-city journeys.

Any surplus revenue from the scheme is to be reinvested into local transportation policies.

[1] Bath & North Somerset Council

[2] Air Quality News

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In March 2021, Bath & North Somerset Council launched a Clean Air Zone in the city of Bath. This case study considers how the council planned and developed the project, highlighting its benefits.

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