France suffered a defeat at the European Union's top court over EU warnings that big cities from Paris to Nice exceeded pollution limits caused mainly by diesel-car engines.
In the first ruling following a recent crackdown on dirty air in nations including Germany, Italy and the UK, judges at the EU Court of Justice said France "systematically and persistently exceeded the annual limit value for nitrogen dioxide since Jan. 1, 2010."
The European Commission sued the nations last year, saying they had failed to meet limits on nitrogen oxide and particulate matter, which are mostly caused by road traffic, industry, heating and agriculture.
"France did not implement appropriate and effective measures to ensure that the exceedance period of nitrogen dioxide limit values would be kept as short as possible within the meaning" of EU law, the Luxembourg-based court said.
Thursday's ruling could offer clues about the outcome of the other pending cases, throwing more spotlight on diesel engines also at the center of an emissions scandal that has roiled the German auto industry.
The engines are the main emitters of nitrogen oxides, which cause respiratory problems and has been linked to premature deaths. Under EU rules, member countries are required to keep the gas to under 40 micrograms per cubic meter.
The ruling highlights the difficulty governments across Europe face to rein in pollution as air quality and climate protection climb up the EU agenda. Under President Emmanuel Macron, France is one of the most vocal proponents of stricter climate policies.
Germany's top administrative court last year issued a key decision that pushed cities toward removing older diesel vehicles from inner cities to improve air quality, including banning some cars. The ruling backed lower courts that argued that forbidding diesel cars in inner cities is the most effective way to cut exhaust-gas levels swiftly and meet EU pollution limits.
