*2.1. Case Study Context*

London is the capital city of the UK with an approximate population of 10 million and this figure is expected to increase dramatically in the near future [29,30]. This rapid growth in the population has led to greater car use and ownership. In 2018, the number of private licensed cars in London had reached about 2.7 million [31], causing serious problems in terms of air quality and health. For instance, a study conducted in London reported that the number of deaths caused by the NOx and PM2.5 as being about 9400 per annum [32]. London is a popular destination for tourists from all over the world, and its air quality is considered the worst among British cities. Therefore, it was selected as a case study since it has an impact on millions of people.

The capital also possesses several characteristics that make it a suitable case for the investigation of banning diesel vehicles. First, it is regarded as a world leading city in the transport innovation and cutting-edge technology, as well as hosting a number of top-class researchers [33]. These factors enable innovative solutions and e ffective intervention measures to be generated [34,35]. Second, it is equipped with suitable tools to facilitate a shift away from diesel vehicles to more sustainable alternatives, as well as encouraging active travel via its sophisticated transport system [36,37]. Third, it o ffers a rich dataset in terms of modelled emissions for di fferent air pollutants that is easily available for research purposes [38].
