Air Quality Strategies and Technologies: A Rapid Review of the International Evidence

Abstract

Poor air quality is a pressing policy issue that spans public health and environmental portfolios, and governments worldwide are investing in a wide array of measures to address it. This paper is a rapid review of the evidence behind air quality strategies and technologies. It was conducted according to the principles of a systematic review, and includes both academic and “grey” literature sources. It focuses on road transport in urban areas, because air pollution tends to be worse in cities, and the main source is fossil fuel vehicles. It draws on the environmental science and policy literature to provide interdisciplinary insight into the most effective air quality policy measures. The most promising initiatives include active travel infrastructure, roadside barriers, low emission zones, and low speed limits. Technologies which remove pollution from the air largely remain unproven, especially at the scale needed to make a significant impact. The combinations of policies from three cities which rank highly for air quality are reviewed; one important finding is that policies are most effective when they are a part of a mutually reinforcing suite of measures. Policies consistent across the cities studied are good public transport coverage, a good cycle network, and financial incentives for electric vehicle purchase.

Banning Diesel Vehicles in London: Is 2040 Too Late?

“…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].…”

“…These factors enable innovative solutions and effective 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 offers a rich dataset in terms of modelled emissions for different air pollutants that is easily available for research purposes [38].…”

“…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].…”

“…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 government 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.…”

“…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.…”