*3.1. Air Quality Satisfaction*

The results show that the highest percentage of respondents (67%) said they "disagree" with the following statement: "I am satisfied with the air quality in London". By contrast, only 22% of respondents stated that they "agree" with the statement, and approximately 12% said they "neither agree nor disagree".

For 67% of the sample population to be dissatisfied with London's air quality calls into question the validity of current policies aimed at reducing the air pollution. This result also indicates that further and quicker actions should be taken by the Mayor of London and the responsible authorities [56] as well as car industries [37], perhaps in conjunction with community-led initiatives. Nevertheless, experts argue that such initiatives led by the community alone are unlikely to have an impact in the long term as they have to be supported by governmental interventions [37].

To highlight the importance of exploring respondents' satisfaction with the air quality, a study conducted by MacKerron and Mourato [57] to assess the relationship between the air quality in London and Londoners' level of life satisfaction, found that air pollution and life satisfaction are significantly correlated, so that, as air pollution increases, Londoners' life satisfaction diminishes. This may suggest that air pollution not only affects people's health, but also their perceptions of life satisfaction. Policymakers are aware of the hazard generated by air pollution and it is therefore incumbent on them to act promptly.

The last survey question was an open question, which sought the respondents' in-depth views on air pollution in London. Regarding air quality satisfaction, one participant stated:

"Air quality is good in London." (male, 24).

Analysing the aforementioned respondent's statement, current studies show that this is not true for London as a whole. In fact, estimates show that air pollution in London contributed to 4267 deaths in 2008 [58] and that this figure had increased to about 9400 in 2015, according to Walton et al. [32]. Since London has consistently breached the legal limits of the PM10 levels, the UK has been threatened with legal action [14]. Poor air quality in London is also a motivating factor that underpins this research since the majority of Londoners stated that tackling air pollution should be prioritised [16]. However, it could be argued that the respondent referred to above may be living in a less polluted area, which they may regard as being, in their judgement, relatively cleaner or at least sufficiently clean. Perhaps it would make more sense if the respondent had stated that air quality is good in their particular area rather than proposing that what discretely applies to one area applies to London as a whole. Respondents who stated that they "neither agree nor disagree" with the statement above might also be living in areas of London that have relatively low levels of air pollution.

### *3.2. Awareness Level of Diesel Vehicle Emissions*

From the analysis in Figure 1, about 33% of the respondents considered themselves to be "moderately aware" of the harm caused by diesel vehicles, while a nearly equal number of respondents claimed they were "slightly aware" or "very aware" of the harm caused by diesel vehicles. Lastly, almost the same number of respondents said they were "not aware at all" as opposed to "extremely aware". This possibly indicates that the sample may have included a wide variety of respondents who come from different backgrounds. Only 9% of the respondents claimed to be "extremely aware", which suggests that they might belong to a group of experts, e.g., experienced transport planners and researchers with a doctoral or masters degree.

Additionally, 26% of the respondents were "very aware" of the harm caused by diesel vehicles. We might speculate that this percentage could include less experienced transport planners as well as researchers and students in related fields. Certainly, it is essential to determine the level of awareness among the population in order to understand how to proceed, and to plan for the next stages. For instance, if there is little awareness about the harm caused by diesel vehicles, then the next step to be taken is to put more efforts into prioritizing new policies aimed at increasing awareness. By contrast, if there is already a considerable level of awareness, then the next step would involve implementing new and more rigorous policies targeting air pollution such as the banning of diesel vehicles [2,7]. Indeed, those who are aware of the harm caused by diesel vehicles would already possess an appreciation of why the government might consider banning such vehicles.

**Figure 1.** Awareness level of the harm caused by diesel vehicle emissions.

Levels of awareness could play a significant role in the shift away from diesel vehicles [56] and any move towards zero-emission vehicles, as stated in the MTS. This argument is also supported by the views of Londoners who completed the survey. In response to the last question, which invited respondents to offer their own recommendations for tackling air pollution in London, two respondents suggested the following:

"Have better knowledge on air pollution." (female, 23).

"To have a screen on the streets that displays real-time air pollution concentrations to make people more aware of the air pollution in the city." (female, 18).

Curtis and Headicar [59] found that raising the public awareness could play a substantial role in persuading people to switch from car usage to other forms of transport. Moreover, it is crucial to make people more aware of the fact that diesel vehicles emit toxic pollutants that are immensely harmful to health. Gaining their trust and confidence would undoubtedly help to implement new intervention measures to tackle air pollution effectively. Some scholars have argued [60] that educating the public about the possible harm caused by diesel vehicles would facilitate the more rapid implementation of the ban as well as facilitating a change in the current composition of vehicle fleets. It is further argued that people who possess awareness of environmental issues and concern about these tend to show positive attitudes towards EVs and other environmentally friendly products [45,61].