Evaluability assessment of low emission zones: Glasgow low emission zone

Background

This working paper describes a preliminary evaluability assessment of low emission zones (LEZs), using the Glasgow LEZ as an example.

It outlines a theory of change demonstrating the links between the LEZ and the range of possible outcomes that could, in theory, be assessed if resources were available.

It is intended to encourage further discussion by relevant agencies and to prompt more detailed examination of specific options for evaluation that have been identified through this evaluability assessment process.

Disclaimer

This paper was written in 2019; however, publication was delayed because of the COVID-19 pandemic.

It was written to the policy context and informed by the available evidence at the time of writing. It has not been updated. Any significant policy changes since then should therefore be considered when reading this report. The reader is advised to review the evidence since 2019.

Appendices

The appendices are provided separately from the main report and are split into three topics.

Appendix 1 includes evidence statements and plausible theory for the theory of change.

Appendix 2 includes a summary of the evidence and plausible theory about the impact of LEZs on air quality and health outcomes and the association between air quality and health.

Appendix 3 summarises the workshop discussions about potential evaluation questions. It includes information that stakeholders were aware of about current or planned monitoring and evaluation at the time of the workshop, as well as suggested research and data sources to address the questions.