Cities can ban diesel cars to tackle NOx pollution when necessary to meet limit values

by Eckard Rehbinder

In two parallel judgments, the highest German administrative court has recently ruled that the authorities of the federal states have the power to impose, in local air quality plans, traffic bans on dirty diesel cars  when absolutely necessary for meeting ambient air quality standards as soon as possible. The two judgments constitute an important contribution to improve the health chances of people who live in urban areas exposed to traffic-related air pollution.  

Recent judgements at the German Federal Administrative Court (Bundesverwaltungsgericht) give authority to the federal states to impose regulations toward meeting ambient air quality standards. Under Section 47 of the German Emission Control Act and the Regulation on Ambient Air Quality Standards and Emission Ceilings which transpose the EU Air Quality Directive into German law, the competent state authorities are obliged to establish air quality plans whenever the relevant ambient air quality standards are exceeded. These plans must provide the necessary measures for a lasting reduction of air pollution; in particular, they must be suitable to keep the duration of exceedance “as short as possible”. The Air Quality Regulation contains a number of ambient air quality standards set by the EU that are primarily designed to protect human health. As regards nitrogen oxides (NOx), the relevant ambient air quality standard is the annual average of 40 micrograms per cubic metre, expressed in nitrogen dioxide (NO2). The Federal Regulation on the Labelling of automobiles with a low contribution to air pollution (Badges Regulation) and the Road Traffic Regulation presently allow access bans only for automobiles that do not have a “green badge”. 

The NOx threshold has been exceeded in about 70 major German cities which raises major health concerns since it is estimated that excessive exposure to NOx may cause the (premature) death of between 6,000 to 13,000 people per year in Germany. The by far most important source of NOx pollution is transport, especially diesel motors used in passenger cars, trucks, buses and taxis. In all these cities the relevant air quality plans provided for “environmental zones” that bar access to the city to very old automobiles that do not meet the more recent EU exhaust standards and therefore did not receive the a green badge. Diesel automobiles that, according to the official classification, comply with the more recent Euro norms 4, 5 and 6 did receive a green badge. This classification has become a matter of heated debate by the gradual revelations in 2015 that certain car-makers, especially Volkswagen, had cheated on diesel emission tests regarding the Euro norms 4 and 5. However, the state governments have shied away from changing the relevant air quality plans and issuing driving bans that would apply to millions of diesel cars that are affected by these manipulations.

Against this backdrop, two environmental associations, the Deutsche Umwelthilfe (DUH – German Environmental Aid) and Client Earth, challenged the sufficiency and hence legality of the relevant air quality plans of the cities of Düsseldorf and Stuttgart in mandamus actions requesting the imposition of access bans for diesel cars. In the case of Düsseldorf, access bans had not even been considered by the state government. In the case of Stuttgart, the state government had taken the view that there were alternative options for meeting the standards. The lower courts decided in favour of the plaintiffs and the relevant state governments appealed directly to the Federal Administrative Court. The issue before the Court was in particular whether the authorities had sufficient powers to introduce traffic restrictions for automobiles that had received a green badge or it was up to the Federal government to first introduce a new system of badges for diesel cars (called “blue badge”). The Court held that EU law which requires compliance with ambient air quality standards as soon as possible overruled German law, that is, the Badges Regulation and the Road Traffic Regulation, where traffic restrictions were the only suitable means to meet the relevant standards in due course. According to the Court, such traffic bans may apply to entire zones or particular routes and be announced by using the normal road signs provided for in the Road Traffic Regulation. However, the Court made important reservations based on the principle of proportionality: The relevant plan must grant sufficient transitional periods and exceptions must be provided for essential services such as ambulances, police cars, waste collection trucks and craftsmen as well as for particular groups of inhabitants.

The Court rulings are landmark decisions that have a potential to improve the health chances of people in urban areas, especially disadvantaged people who for economic reasons live in high traffic areas. They also contribute to making association suits in the field of health and the environment more effective. Although German law provides for mandamus actions, including actions brought by environmental associations, the chances for success of plaintiffs in mandamus procedures normally are very small. That an environmental association can impose its legal point of view on an entire powerful industry, is rare. In both respects, the rulings contribute to implementing the SDGs 3 and 16 and they may have repercussions in other countries that are confronting the same problems. However, the potential negative consequences of the rulings are equally far-going as they may affect road traffic of millions of car-owners, especially commuters, and will certainly adversely affect the market for used diesel cars. As a result of the Court rulings, the state governments will at least have to reconsider the relevant air quality plans. The question as to what exactly means keeping the duration of an exceedance “as short as possible” is still an open question, although the European Court of Justice has already held that even “drastic” measures may be necessary.

Most state governments and the Federal government want to avoid traffic restrictions by taking recourse to alternative options. However, one cannot take it for granted that this strategy will always be successful. The Administrative Court of Stuttgart had already held that under the particular topographic conditions of that city, diesel automobiles which only comply with the Euro norms 4 and 5, will most probably have to be banned. The problem is that, where traffic restrictions will be introduced, they may simply lead to shifting the traffic and creating chaotic traffic conditions and/or new hot spots, which will then result in a prolongation of the status quo and possibly a new series of litigation. At federal level, negotiations between the government and the German automobile industry resulted in action by industry to update the relevant software, whereas industry could not be persuaded to retrofit the affected diesel motors at its own cost. These negotiations preceded the Court ruling, and industry may now be more prepared to assume financial responsibility for its own mistakes of the past, at least part of it. One may expect new initiatives in this direction, and be it simply for avoiding the impression of a tacit cronyism between government and the automobile industry. It is also worthwhile noting that the EU Commission has instituted infringement procedures against Germany (as well as 7 other EU member states) because of non-compliance with the ambient quality standards for NOx.   

Eckard Rehbinder is an Emeritus Professor of Economic and Environmental Law at the Research Centre for Environmental Law, Goethe University Frankfurt, Germany. 

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