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Clean air zone

Like many other urban areas, Cambridge has an air-quality problem – there’s a lot of transport-related pollution.

Cambridge is an important centre for employment, education and tourism, leading to an above-average number of vehicles on the roads. And the nearby A14 is used by a lot of freight traffic, much of which comes into the city on the trunk roads.

We’ve designated the city centre as an air quality management area, because of the high average level of nitrogen dioxide.

But Cambridge is growing rapidly, and a further increase in traffic could easily cause an unacceptable rise in air pollution. So we and our partners looked at the feasibility of introducing a clean air zone in Cambridge.

A clean air zone is an area where targeted action is taken to improve air quality. This can deliver improved health benefits and support economic growth.

In a clean air zone, there is a focus on reducing emissions of pollutants and carbon emissions. Any improvements made to air quality should be designed to last for a long time. Pollution should not be increased by growth in population, new buildings or changes in land use.

  • Clean air zones reduce public exposure to polluted air and pollutant emissions, including nitrogen dioxide.
  • Clean air zones improve the quality of life for those people who live, work, and study in the city, as well as visitors.
  • Clean air zones reduce the number of people affected by health conditions caused by poor air quality, reducing pressure on local health services.
  • Clean air zones provide an incentive to use cleaner and active modes of transport, with increased health benefits.

Feasibility study

We ran a feasibility study to investigate whether introducing one or more clean air zones in Cambridge would help reduce air pollution. It was funded by the Greater Cambridge Partnership, and the county council also took part as the authority responsible for roads.

Among the issues we considered were:

  • Location – We considered which areas have poor air quality and what vehicles drive to or through them. And we investigated how other nearby areas might be affected by restricting vehicular access in clean air zones.
  • Vehicular access – There are different classes of clean air zone, to determine what types of vehicle are allowed in them. We assessed each class and considered whether it’s appropriate for Cambridge and whether it would deliver improvements to air quality.
  • Whether to charge for access to the zones – We assessed whether or not to introduce a charge to enter any implemented zones. Any revenue raised by a charge would be used to fund the scheme itself and other local transport improvements.
  • Effects on residents – We considered the health, social and economic impacts any zones might have on the people living in them.
  • Other measures – We also considered the impact of any other measures being assessed or implemented to reduce pollution.

The government’s clean air zone framework provides clear guidance on what types of vehicles can enter each class of zone. Zero-emission vehicles and ultra-low emission vehicles operating in zero-emission mode are unrestricted.

Key points

The key points that came from the study are highlighted below:

  • In Cambridge and South Cambridgeshire 106 deaths per year can be attributed to poor air quality.
  • The main source of emissions in Cambridge is from road traffic. Buses account for 49% of the nitrogen oxide emissions in the city centre, and diesel cars contribute a further 32%.
  • Without any interventions, exceedances of the current air quality limit value for annual average NO2 concentrations are predicted at locations in the city centre in 2021 and 2031.
  • Consideration of the government’s suggested clean air zone classes has shown that introducting a charging class-D zone for the inner ring road and the area inside it would reduce annual mean NO2 concentrations to below the current air quality limit value in 2021. It would also reduce annual mean NO2 concentrations across Cambridge by 43%.
  • The predicted growth in traffic levels between 2021 and 2031 means further action will be required to maintain annual mean NO2 concentrations below the current limit.
  • The introduction of a clean air zone requiring all buses, coaches, taxis, private-hire vehicles and LGVs to be ultra-low or zero-emission vehicles by 2031 was found to reduce the NO2 annual mean concentrations to below the limit. It resulted in a reduction of 80% in annual mean NO2 concentrations across the whole city. This scenario allowed HGVs to be Euro VI and did not place any restrictions on private vehicles.

Next steps

You can read more about the feasibility study on the Greater Cambridge Partnership website.

We anticipate that any engagement with businesses and residents on the potential options that have emerged from the report, or other options being considered by the GCP, will take place in 2019. Feedback from this will help in the development of any formal proposals.

Other measures

Introducing a clean air zone is just one measure we and our partners are looking at to improve air quality in Cambridge.

We’re also considering how to improve cycling and walking facilities. And we’re working with local taxi firms and bus operators to encourage the use of ultra-low and zero-emission vehicles.

Further actions that we are considering are outlined in our Air Quality Action Plan [PDF, 3MB].

We’ll consider the influence of these and other measures on air quality in Cambridge. And we’ll assess whether the addition of a clean air zone would complement them or whether they are already sufficient.

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