Paris is continuing with controversial traffic control measures as the city faces its worst winter pollution in 10 years.
City hall officials have barred half of all cars from travelling and made public transport free for a third consecutive day. A similar scheme will be implemented in the city of Lyon on Friday.
Only vehicles with even-numbered plates are allowed to drive on Thursday in the French capital and its close suburbs.
But the ban was not respected by many drivers on Wednesday while disruption to public transport services added to confusion.
To tackle the crisis, Paris's Velib bike-share and Autolib electric cars will again be free on Thursday, as well as the Paris metro and bus services.
The body in charge of monitoring pollution said the peak is due to the accumulation of pollutants because of anticyclonic conditions.