*3.4. Banning Diesel Vehicles*

Perhaps, surprisingly, analysis of the survey results revealed that the vast majority of respondents would support the ban. About 65% of the sample population agreed with it, as opposed to 20% who would not be in favour. Nearly 15% of the sample population said they "neither agree nor disagree" with the ban, which suggests that they might be open to new policies and would not be considered problematic or non-compliant should such a policy come to be enforced.

A selection of the respondents are cited below expressing their views about the ban:

"I have only recently found out how bad diesel cars can be. It is a grea<sup>t</sup> initiative to ban them, but the governmen<sup>t</sup> should give diesel car owners a huge incentive to compensate for the purchase of a new car that meets their requirements." (male, 42)

"Ban diesel cars, educate people to shift from cars to public transport, and increase diesel prices" (female, 36)

"Getting rid of diesel is just a start, we should work towards banning all private cars as soon as possible, including electrics which waste as much space." (female, 28)

"I would support more punitive measures including the expansion of the Congestion Charge Zone/London LEZ and even higher costs for diesel engines in Parking Control Zones. Also, a London based scrappage scheme which should incentivise diesel car users with active travel-based solutions, e.g., trading your diesel car for a new bike/public transport season ticket etc." (male, 37).

Of those surveyed, almost 13% advocated the ban when asked about recommendations for improving air quality in London in the open survey question. Therefore, support for a policy enforcing a ban is a conclusion that can legitimately be drawn from the data analysed in this research.

It is believed that banning diesel vehicles would create a positive impact on the environment by reducing the amount of air pollutants in the atmosphere. In Delhi, for example, slightly less than half of the diesel vehicles were replaced by compressed natural gas (CNG) alternatives [59]. Interestingly, in just one year, ambient air pollutants were reduced significantly. The case study reported reductions in sulphur dioxide (SO2), carbon monoxide (CO), and NOx by 22%, 10%, and 6%, respectively [59]. We can speculate about what the impact would have been if those diesel vehicles were replaced by zero emission EVs. Likewise, in the context of London, if a total ban on diesel vehicles is implemented, a positive impact would be seen in terms of reductions in pollutant concentrations, similar to, or possibly better than, those reported in the Delhi case study, since they would be replaced by EVs rather than CNG, which represent a more attractive alternative in terms of emissions produced.

Experts argue [7] that banning diesel vehicles would cause a substantial reduction in the NOx and PM2.5 emissions of 47% and 52%, respectively on the 2015 levels by the year 2030. Reductions in the NOx and PM2.5 levels would contribute to savings totalling 300 Disability Adjusted Life Years (DALYs). One DALY can be defined as the loss of the equivalent of one year of full health [64]. By the year 2024, diesel vehicles would be responsible for about 6300 DALYs. In the light of these findings, we can claim with confidence, that mitigation measures, i.e., banning diesel vehicles, should be considered as soon as possible. It is further argued that the ban would not only improve air quality and people's health but would also increase the uptake of EVs, especially if the appropriate infrastructure is in place [7].

Although some scholars [16] claim that there is little point in banning individual vehicles from certain roads because doing so would only improve air quality on those particular roads, but could consequently displace the pollution onto other roads, it can be argued that the ban first needs to be tested on specific roads for a certain period of time before implementing it across the entire city. People on low incomes who use their vehicles for their daily commute to work would be the group affected most by the ban since they may struggle to purchase newer models. If the ban is proven to achieve the desired outcomes in respect to improved air quality, then those people could be o ffered incentives to switch to more environmentally-friendly vehicles or, for instance, benefit from reduced public transport fares.

If policymakers also advocate implementing the ban but have concerns regarding the public acceptability, then the policy could be introduced gradually or on a trial basis. For instance, policymakers could initially enforce a ban on the most polluted roads by restricting the entry of diesel vehicles only. They could also enforce a ban in di fferent areas for a limited amount of time, and then if this was found to result in significant reductions in pollutants levels by monitoring progress, the ban could be extended to more areas of London, thereby increasing the public confidence in respect to any proposed ban.

Overall, it is highly desirable to phase-out all old diesel vehicles since they cause higher levels of pollution than newer models [2,37,56]. In addition, new buses and taxis operating in London are more environmentally benign and thus should also be considered as an alternative to current diesel-fuelled vehicles [17,37].

### *3.5. Type of Vehicle Owned by Participants*

The results of this survey question provide an insight into the proportion of car users in addition to the engine type of their vehicles. As can be seen from the analysis in Figure 2, at least 61% of the respondents were car users, while 39% were non-car users. It can be assumed that some respondents were also car users but did not own a car. The following questions were aimed at eliciting whether car drivers would be willing to switch from ICE vehicles to the use of EVs as the 2040 ban would apply to both petrol and diesel vehicles. If the number of car drivers in this survey had been very low, then the survey analysis would be inadequate because car drivers are the targeted group in respect to their attitudes towards the forthcoming ban and their willingness to shift to more environmentally-friendly alternatives. Therefore, as more than 61% of the respondents were car drivers, the analysis can be considered valid, although it may be desirable to increase the sample size in further research.

In 2016, there were 39% diesel vehicles, 60% petrol vehicles and 1.3% other vehicle types (EVs and hybrids) in Great Britain [3]. These statistics are consistent with, and to some extent similar to, the survey results in terms of the proportion of each vehicle type among the population, which suggests that the survey succeeded in reaching the targeted groups and being representative of the overall population.

**Figure 2.** Type of vehicle owned.

### *3.6. Shifting to Electric Vehicles*

Remarkably, over 68% of car drivers said they would agree to replace their current vehicles with EVs, as opposed to 20% who would refuse. Just under 12% of the respondents claimed to "neither agree nor disagree" with replacing their vehicles with EVs. It may be possible to persuade this group to switch to EVs by providing scrappage schemes or incentives to purchase them [37,56]. Therefore, one implication of this is that the governmen<sup>t</sup> should provide a scrappage scheme for old vehicles to encourage both those who "disagree" and those who "neither agree nor disagree" to consider this option.

When participants were asked about their recommendations for tackling air pollution, nearly 12% responded that the adoption of EVs would provide a solution. Furthermore, about 8% of the participants said that incentives are necessary in order to persuade people to switch to EVs, while others complained about the high prices of EVs. It is therefore proposed that the governmen<sup>t</sup> and Mayor of London should incentivise the purchase of EVs to increase their uptake rate. Below is a selection of the participants' opinions:

"London's air quality could be improved by the governmen<sup>t</sup> giving incentives and benefits when people purchase an electric car." (male, 50).

"Diesel cars should be a relic of the past. We need to improve the performance of electric vehicles and lower their cost so that they are more widely adopted." (female, 39).

The KWT was employed to test the relationship between the willingness to switch to EVs and the likelihood of supporting the ban. The results revealed that an H value of 13.07 was obtained, as highlighted in Table 2, suggesting that a statistically significant relationship exists. As such, those who are willing to replace their diesel/petrol vehicles with electric ones are more likely to support the ban. Therefore, if the Mayor wishes to implement this policy soon, it is advised that the incentives for choosing EVs be put in place [37]. This programme could also be stimulated by the market. For instance, car manufacturers should be encouraged to be ambitious to produce more EVs and fewer ICE ones. After all, as discussed in the analysis, over 68% of car users agree on the need to shift to EVs.

As stated in the MTS [17], the goal is for all newly registered vehicles in London to be zero emissions so as to achieve the zero-emission road transport by 2050. Therefore, it is vital to discuss which factors would influence the acceptance of EVs in the capital to rapidly increase their adoption as a way to address air pollution.

Fundamentally, moving towards a more sustainable transport system through the uptake of EVs is critically linked to the level of public awareness and concern about the environmental impacts of ICE vehicles as well as EVs. For instance, Khaola et al. [65] investigated a possible correlation between people's concern for the environment and their attitudes towards green products (e.g., EVs) in general and found that there is a strong correlation between them. Additionally, Dogan and Ozmen [66] surveyed 752 respondents to investigate how the environmental concern would affect participants' attitudes towards buying EVs, and they discovered that participants with higher levels of environmental concern were more interested in EVs and more likely to purchase them.

Furthermore, it is argued that those who seek additional knowledge about EVs may be strongly influenced in terms of positive attitudes towards EVs. Many authors argue [20,67] that having a prior knowledge about EVs can make a huge di fference regarding the decision-making process of buying EVs compared to those who have little or no knowledge.

Another factor that is believed to influence the adoption of EVs is incentives [68]. Studies show that providing incentives exerts a positive influence on purchasing EVs [69,70] given that the higher the incentive, the more likely people will purchase an EV. Incentives can be provided in di fferent forms such as tax rebates and subsidies on purchase [71]. A tax rebate of £1000, for example, means that individuals will have a £1000 reduction in their tax when they purchase an EV. A study that was conducted in the United States showed that \$1000 in tax rebate resulted in a 2.6% increase in EVs sales [71]. It is suggested that a similar method be used in London to encourage more people to purchase zero emission vehicles as an alternative to more polluting ones.

Although EVs are being introduced as an alternative to break fuel dependence and tackle other environmental problems [67], it is imperative to acknowledge that non-exhaust emissions should be also be taken into account when considering how best to address air pollution. There is a substantial volume of literature that has reached the conclusion that the volume of emissions from non-exhaust sources is much greater than emissions from vehicles exhausts [12,72,73]. Therefore, the goal of zero-emission road transport cited in the MTS is most likely to be achieved when there is almost no car use. Otherwise, it would be very challenging to realise this ambitious vision set out by the Mayor in the event that private cars, taxis, and buses continue to operate on London's roads. However, the phasing-out of ICE vehicles would significantly improve the NOx reductions [7] since EVs do not emit those kinds of pollutants.

### *3.7. Influence on which Kind of Vehicle to Purchase*

The findings from Figure 3 highlight the importance of providing information (i.e., raising awareness) about the harm caused by diesel vehicles, as the participants showed positive attitudes towards low emission vehicles such as hybrids and EVs. Interestingly, about 60% of those surveyed said that they would purchase a low-emission vehicle including hybrids and EVs. Furthermore, about 4% of the respondents stated that they would not purchase any vehicle because they prefer to use other types of public transport such as trains, buses, and cycling. In addition, the most remarkable observation to emerge from comparing Figures 2 and 3 is that the percentages of diesel and petrol vehicles dropped by more than half, from 18% to 8% and from 37% to 17%, respectively.

**Figure 3.** Which kind of vehicle to purchase in the future.

The KWT was also employed here to ascertain the e ffect of providing information on people's decision-making when buying a new vehicle. The test results presented in Table 1 reveal that providing people with relevant information about the potential harm caused by emissions from diesel vehicles will influence their decision-making process and, ultimately, lead them to make more environmentally friendly choices. It might be argued that those who are considering purchasing a more environmentally friendly vehicle are more likely to agree with the ban on diesel vehicles. Therefore, it is essential that the motor industries ge<sup>t</sup> involved [37] with this movement towards a sustainable zero-carbon road transport system by providing more environmentally friendly vehicles to help more people to make the shift away from ICE vehicles. This view was also expressed by one survey respondent:

"I think the car industry needs to be the leader. Technology can be used to assist in sustainable & cost-effective vehicles and transport modes." (female, 29).

Below is a selection of the participants' views about, and recommendations for, improving the local air quality in London:

"Air quality could be improved by creating more green spaces and trees as well as encouraging people to use public transport. Electric vehicles are the future, but at the moment they do not seem to be viable on a large scale due to their high cost." (male, 25).

"Encourage people to use environmentally friendly vehicles by reducing their price." (male, 19).

Although the findings in Figure 3 indicate positive attitudes towards different types of EVs, many researchers [74–76] believe that the high cost of purchase represents a barrier to the adoption of EVs, which concurs with the views cited above. Additionally, several authors [67,68] have identified other potential barriers to the adoption of EVs, such as their limited range, as well as style, size, performance and safety.

Nonetheless, some of these barriers could potentially be overcome by driver training, for example to address the problem of EV's limited mileage range [67]. Moreover, it is important to understand the specific needs and requirements of Londoners in relation to a vehicle. This could help to develop effective policies and stepping-stone guidelines for car manufacturers so as to overcome some of the aforementioned barriers. Two key factors could foster the acceptance of EVs, namely providing incentives in different forms, and raising consciousness about and concern for the environment through awareness campaigns. Acceptance can also be increased by advertising and marketing, which might include word-of-mouth recommendation [77]. Additionally, Globisch et al. [78] stressed the importance of providing EV users with the necessary information, support and assistance to overcome technical failures, as a way to foster the EV deployment. They also found that focusing on the vehicle design (perceived enjoyment) of EVs can significantly influence the choice of the car purchased.

Intervention by policymakers could also make a difference [79]. For instance, a new policy could be introduced stipulating that, for every sports car sold by manufacturers, five EVs should be sold. This would even-out the total amount of emissions produced by a particular car manufacturer since sports cars emit more pollutants than EVs [80]. It would also potentially encourage car manufacturers to set ambitious goals in terms of increasing the EV sales using different methods such as awareness-raising campaigns, and more efficient marketing tools, as well as providing customised assistance to their users.

### **4. Conclusions and Policy Implications**

Using London as a case study, this paper explored the public opinion and respondents' views regarding the forthcoming ban on diesel vehicles, examined whether the ban could be implemented earlier than 2040, and set out to discover Londoners' attitudes towards switching to EVs.

The analysis from the KWT revealed that being concerned about the environment, together with an appropriate level of awareness surrounding its vulnerability to certain hazards, could play a huge role in supporting the ban. In order to facilitate the implementation of the ban, it is highly recommended that Londoners' level of awareness about the harm caused by diesel vehicles needs to be increased, which can be achieved by awareness-raising campaigns. Findings from the survey also revealed that the majority of participants "agree" with the ban, suggesting that the policy can be implemented well before 2040. These results have been very encouraging, and the discussion proposed several courses of action for the policy of banning diesel vehicles.

This work has shown substantial evidence that the majority of car drivers—slightly less than 70%—would agree to switch from driving ICE vehicles to EVs. However, some participants raised concerns about the high price of EVs whereas others proposed that the governmen<sup>t</sup> should provide

incentives for people to switch to EVs, which suggests that Londoners may not be willing to pay more for a private transport. A further important implication is that Londoners must be provided with incentives tailored to their needs, as well as ways of increasing their awareness of and concern for the environment as a solution to facilitate the acceptance of EVs. Another factor likely to enhance the EV policy and uptake rate is the banning of diesel vehicles, if the appropriate infrastructure is provided. This may include creating su fficient charging stations and extending the installation of charging points to cover more residential areas as well as carparks [20,67,81].

Our findings will be useful for the Mayor of London and policymakers to push the Agenda 2030 forward so as to achieve the goals of sustainable cities and communities as well as climate action [82]. This paper has led us to conclude that the ban should be enforced as soon as possible since the majority of Londoners appear to support the initiative, according to the sample in this research. We would argue that even if CO2 emissions were to be controlled and reduced, the overall climate change e ffect would still exist because of the time scales involved, meaning that it takes a long time to reverse the severe impacts of poor air quality [18]. In order to achieve the desired outcomes for air quality in the long-term, critical decisions must be taken and "aggressive" policies implemented now to determine the quality of London's air in the future.

**Author Contributions:** M.S. primarily ran the modelling, produced the figures and tables, designed the questionnaire, collected the surveys, and co-wrote the manuscript. M.C. designed the questionnaire, further interpreted the modelling results, commented on the interview results, and edited the manuscript. Y.Z., C.P., X.G., and Y.L. commented on and edited the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to thank the two special issue editors and the three anonymous reviewers for their suggestions regarding the improvement of the initial draft. This research did not receive any specific gran<sup>t</sup> from funding agencies in the public, commercial, or not-for-profit sectors.

**Conflicts of Interest:** The authors declare no conflict of interest.
