Portsmouth’s Clean Air Zone: The Bare Minimum or Simply Inadequate?

Portsmouth City Council recently proposed a reduced Clean Air Zone to improve air quality in the city. Local air quality campaigner for Let Pompey Breathe, Tim Sheerman-Chase, explores the proposal and questions whether the plan will be enough to bring the city within legal pollution limits in the next 3 years. 

Portsmouth City Council has proposed a mini-Clean Air Zone class B which just covers the city centre. According to their computer models, this will be sufficient to bring the city within legal pollution limits by 2022, which is assumed to be ‘as soon as possible’ to comply with the law.

Area of the proposed mini-CAZ. Image by Portsmouth City Council.

The council are relying on predictions by computer models to determine what course of action to take. However, the quality of the predictions depends on the validity of their assumptions. There is a well known saying that if you put ‘garbage in’ to a model, you will get ‘garbage out’.

PCC has made many predictions over the years that have turned out to be false. For example, in the 2010 plan, PCC states they will reach legal levels by 2012-2016. In 2015, it was supposed to be below the legal limit by 2020. In 2017, it was expected by 2021. Their predictions have repeatedly failed. Now we are expected to believe their latest estimate that they will be legally compliant by 2022, but it does not seem that lessons have been learned from past failures.

The most likely sources of error in these predictions are traffic growth estimates (driven by new developments), and the predicted shift to more efficient vehicles, but regardless of the specific cause, it is clear that something is very wrong.

Apart from the repeated failure of modelling, the case study data of similar class B clean air zones have shown only a slight improvement after their introduction. This does not meet the challenge that Portsmouth faces which requires around a 10-15% cut in NO2 pollution.

The computer models are not solely produced by PCC, but are done under a DEFRA (Department of the Environment, Fisheries and Rural Affairs) mandated methodology by an outside consultant. PCC has described some of the instructions by DEFRA as ‘deeply unhelpful’. It could be that DEFRA is using faulty models that are overly optimistic and will avoid central government having to tackle the problem, which saves them money. It may also be that air quality consultants that use model analysis are selected based on their willingness to tell the government what they want to hear. I have had private discussions with well-placed people in which they have expressed concern over the validity of the modelling.

In September 2019, Gerald Vernon-Jackson, Leader of the Council, said the scheme would go ahead ‘even though we know it will be ineffective’. However, in a BBC report on the revised scheme in October, Cllr Dave Ashmore, Cabinet Member for Environment and Climate Change said, ‘Reducing the size of [the zone] makes more sense and tackles the area where air quality is worse.’

The Council is in a difficult position because it doesn’t seem to have the resources to tackle the air pollution problem independently and DEFRA will only fund the minimum scheme needed to reach legal pollution levels. If councillors go along with the mini-CAZ class B, which is the minimum based on DEFRA specified modelling, they are likely to fail in achieving legal pollution levels any time soon. If they object to DEFRA’s methodology, they fear they may get no funding at all. It’s either crumbs or nothing for Portsmouth, it seems.

The council has not done itself any favours by repeatedly failing to explain the need for a CAZ and the benefits of introducing one. Instead, Cllr Vernon-Jackson is clear the CAZ scheme is not a local choice but ‘a government imposed scheme’. It could be argued this characterisation of clean air zones will leave local people feeling imposed upon rather than helped.

However, the primary purpose of the clean air zone is to improve public health. According to Portsmouth City Council’s Public Health Annual Report 2016, ‘air pollution causes an estimated health burden equivalent to 100 deaths a year. This is largely through an increase in diseases affecting the heart and lungs.’ The numbers may be even higher, as studies have found a strong link between air pollution and heart attacks, strokes and acute asthma.

As to the assertion that the CAZ scheme is being imposed on the city, strictly speaking, Portsmouth has a choice of implementing a CAZ or other measures that are at least as effective. The council, under various administrations, has had many years to tackle the problem and made no progress in reducing pollution levels. It is only due to this repeated failure that considering a CAZ has now been mandated. However, central government has also caused problems by dragging its feet on encouraging compliance and refusing to produce funding for schemes that would make a positive difference.

For the past year the council has been working on a new air quality plan for submission at the end of October 2019. In it they have modelled various types of clean air zones, such as a class C zone including light goods vehicles, and a class B zone excluding light goods vehicles. The Council states:

Class B CAZ is combined with a number of non-charging measures to ensure that compliance is achieved within the shortest possible time i.e by 2022. The alternative to this is to go to the Benchmark option of implementing a Class C CAZ which it is anticipated will achieve compliance in all locations by 2022, however it is anticipated that this will have a greater negative impact on Portsmouth’s residents and the local economy.

It seems absurd to suggest that the stricter class C will be no more effective than a class B CAZ. It is also unclear why a class D, which covers private car usage, was not modelled. Common sense would seem to indicate that this would be even more effect and therefore be legally required.

The main concern with the restricted area of the proposed CAZ is that it is less effective when compared to a city wide scheme. It risks the traffic simply re-routing outside the CAZ and I would anticipate a significant increase in traffic down Copnor Road, the Eastern Road and possibly Albert Road as people avoid the charging area. Some of these roads are already over the legal limit or barely compliant, including Velder Avenue, Milton Market, Fratton Bridge, etc. Is PCC trying to redistribute pollution so the total remains the same but it is evenly distributed around the city?

The recently published plan from the council does little to address these concerns. The plan is now with DEFRA for final approval. Without a credible plan, Portsmouth City Council and DEFRA are venerable to further legal challenges, as well as putting public health at risk.


Further information

Portsmouth City Council – Air quality in Portsmouth

#LetPompeyBreathe is a joint initiative involving Portsmouth Green PartyPortsmouth Friends of The EarthMilton Neighbourhood ForumKeep Milton Green, Portsmouth Greenpeace, Greens in the European Parliament and other groups concerned with the dangerous state of Portsmouth’s Air Quality.  Visit their website for more information and follow them on Facebook and on Twitter using #LetPompeyBreathe.


The original version of this article appeared on Let Pompey Breathe.