2021 Annual Report for the Evaluation of Local NO2 Plans

Local authorities across England with persistent exceedances of roadside NO2 (nitrogen dioxide) concentrations are working to develop and implement their Local NO2 Plans, aiming to reduce these concentrations to within statutory limits in the shortest possible time, as required by the Government.

The Joint Air Quality Unit (JAQU), a joint unit between the Department for Transport and the Department for Environment, Food and Rural Affairs, commissioned Ipsos, working in partnership with the Institute for Transport Studies (ITS) at the University of Leeds to deliver the Central Evaluation of the impact of these Local Plans on air quality and behaviours.

The aim of the Central Evaluation, which has been running since 2019, is to provide insights to support adaptive and future policymaking and inform on the implementation of Local Plans. The first annual report was published in February 2021 and provided an overview of the situation in Local Plan areas before any measures were implemented. After a second year of research, this 2021 Annual Report presents the results of the analysis completed between December 2020 and December 2021, which focused on the first areas to have implemented a CAZ. The report presents findings to understand if and how the Local NO2 Plans have affected air quality, traffic and travel behaviours so far.

Ipsos’ research with residents in two Local Plan areas shows that, following their introduction, CAZs have led to changes in travel behaviour, with 39% of Birmingham residents surveyed and 25% of Bath and Northeast Somerset residents surveyed reporting changes in their travel behaviour – such as using a different mode of transport or taking a different route to travel. Findings from research with businesses show that there was more support than opposition for the measures, and that, overall, the businesses surveyed felt that the measures had a low impact on them. The report also outlines that there was limited evidence suggesting that the CAZs have led to accelerated vehicle upgrades.

The analysis of air quality conducted by the Institute for Transport Studies, in partnership with Ipsos, found that NO2 and NOX (nitrogen oxides) concentrations have decreased in Bath since the CAZ implementation. While these trends have been deeply affected by COVID-19 lockdowns in the UK over the period analysed (October 2020 to October 2021), along with a local bridge closure in Bath, closer analysis of traffic flow, composition and modelled emissions, alongside an analysis of air quality in comparable locations, suggests that the improved air quality observed may be partially attributed to the CAZ introduction.

The next annual report will provide insights into the longer-term impacts of the CAZs in these two areas, and the early impacts of plans in other LAs, including those not implementing a CAZ.