Many German and European cities are facing the prospect of diesel bans due to excessive air pollution from nitrogen dioxide (NO2). The European Commission has warned that it will impose penalties on cities that continue to exceed the annual limit values set for this harmful pollutant. A research team at the IASS has criticised political measures geared mainly at incentivising the purchase of new diesel vehicles: In their latest Policy Brief, Tackling Urban Air Pollution: Nitrogen Oxides and Diesel Emissions, Tim Butler, Erika von Schneidemesser and Sophia Becker write that “the current set of incentives for the purchase and use of diesel vehicles works against air quality targets.” The authors also show that a scheme for trading in old diesel cars for new ones will not contribute to improving air quality in our cities. By their very nature, diesel cars emit more nitrogen oxides than their petrol counterparts. And given that new diesel models are generally larger and more powerful than modern petrol cars, they will at best be able to match the emissions of the latter. In addition, a number of exceptionally polluting Euro 6 models, with real-world nitrogen oxide emissions far in excess of what they should be, can still be legally sold until September 2019. The proposed discounts on new diesel cars will also apply to them.
Rather than measures that encourage consumers to buy new diesel cars, the authors advocate a reduction of the total diesel share in the German car fleet as well as a new approach to mobility, where public transport, carsharing, e-mobility, and renewable energy-powered transit options play a more prominent role.
The authors of the Policy Brief make three concrete policy recommendations:
Extend measures to reduce NOx emissions to entire urban areas
Limit values are consistently exceeded in locations with heavy traffic throughout urban areas, not just at “hotspots” in the vicinity of monitoring stations. To adequately protect human health, measures to reduce NOx emissions from diesel passenger vehicles need to be implemented across whole urban areas.
Design and enforce reduction measures based on real-world emissions
Given the large discrepancy between the NOx emissions car manufacturers register for their vehicles and those measured under real-world conditions, measures to reduce NOx emissions from diesel cars must be based on real-world emission measurements. Proxies for estimating vehicle emissions, such as vehicle age, will not adequately address the issue.
End subsidies for diesel fuel
The incentivisation of diesel vehicles through indirect fuel subsidies justified by their purported climate benefits should be phased out. Today’s diesel passenger vehicles do not emit less CO2 relative to their petrol counterparts. Furthermore, subsidies that support fossil fuel combustion work against long-term sustainability goals.
IASS Policy Brief: Butler, T., von Schneidemesser, E., Becker, S. (2018): Tackling Urban Air Pollution: Nitrogen Oxides and Diesel Emissions