Paris has suffered its most serious surge in air pollution for a decade, experts have warned.
Airparif, an organisation which monitors air quality in the French capital, said levels have reached the "alert threshold".
So city officials have implemented a series of measures in an attempt to tackle the problem.
All public transport has been made free on days when smog was particularly bad in an attempt to encourage residents to avoid using their vehicles entirely.
The Velib' bicycle and Autolib' electric car schemes were also made free of charge in the hope of deterring people from driving.
They have previously introduced a rule that alternates the days that cars can be driven into the city depending on whether they have odd or even number plates.
The City of Lights has previously banned vehicles built before 1997, which affected around 10 per cent of cars on the road.
"Cars are poisoning the air. We need to take preventive measures," said Paris city hall transport official, Herve Levife.
"We want these bans to automatically take effect when the pollution exceeds a certain level, not have to negotiate them with the Government each time."
Fine-particle air pollution in France causes approximately 48,000 premature deaths a year.
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