Hamburg on Thursday became the first German city to ban older diesel vehicles from some roads, a measure that is largely symbolic but disputed by carmakers and the government.
A 1,600-metre (one-mile) stretch of highway and a 580-metre section of another major road are now closed to diesels which do not meet "Euro-6" emissions standards, with signs to indicate that the restriction is now in force.
The first ban came after the Federal Administrative Court found in February that such restrictions were a legitimate way for local authorities to bring air pollution below European Union health thresholds.
But Hamburg's partial ban is being met with skepticism in Germany.
"It's symbolic politics. The authorities are blocking only two roads, so only 1,787 residents out of the 1.8 million inhabitants of Hamburg are affected by these restrictions," wrote Spiegel in a commentary online.
The move was simply aimed at showing the EU that authorities were taking action to bring down pollutant levels, the magazine suggested.
Nevertheless, Chancellor Angela Merkel's government is watching the trend warily, mindful of the number of jobs at stake in the auto industry, which risks being shaken up if other German cities follow suit.
The cities of Stuttgart in the south and Kiel in the north are mulling their own diesel restrictions in the battle against air pollution, while Munich, Cologne and Duesseldorf are closely monitoring the Hamburg experiment.
The diesel engine industry has come under intense pressure after Volkswagen admitted to fitting 11 million vehicles with illegal devices to cheat pollution tests.
Jens Kerstan, the official in charge of environment in Hamburg, acknowledged that the ban would cause hardship for "innocent car owners, but it is unavoidable because carmakers tricked us and the government has tried for many years to do nothing."
Germany's federal government has often appeared to take the car industry's side.
It has pushed back against diesel bans and rejects the idea of a "blue badge" drivers could stick on their windscreens that would identify the least polluting vehicles.
Instead, Berlin has offered longer-term measures like a cash pot to extend public transport and build up cities' electric vehicle fleets.
Explore further: Hamburg is first German city to order diesel bans