Friday will mark day four of traffic restrictions in Paris and its suburbs, and will also see similar restrictions in Lyon and nearby Villeurbanne.
In the capital, only motorists with odd-numbered registration plates will be allowed on the roads, a rule that has been in place since Tuesday, alternating between odd and even plates.
Authorities will also make public transport in the capital free for the fourth straight day (costing a daily €4 million) and will enforce reduced speed limits in some departments by 20 km/hr.
Lyon Mayor Gérard Collomb has also called for public transport to be free on Friday, good news for the hordes expected to descend on the town for the three-day Festival of Lights that kicks off on Thursday.
While critics have said the bans don't actually help reduce pollution (the levels of which rose in Paris the first day after the traffic bans), authorities are also having to deal with motorists who simply aren't following the rules.
“I wasn't going to buy another vehicle to go to work today!” said 31-year-old builder Jug, who was waiting in his truck to pay a fine of €22 ($24) after being stopped by police.
Traffic jams in the morning rush hour were 415 kilometres (258 miles) around Paris, compared with 300 normally, local road traffic officials reported.
On Tuesday alone, police handed out a whopping 1,700 fines to motorists who were ignoring the rules.
While there are as yet no traffic restrictions elsewhere in France, southern city Marseille and Rennes in the west are on standby, while central Orleans and Rouen in the north have noted increased pollution levels.
So why the pollution?
The surge in pollution has been driven by cold weather and near windless conditions that have trapped exhaust fumes, smoke from wood fires and other pollutants, according to the French capital's AirParif air monitoring service.
Although bad by Paris standards, current levels of fine airborne particles, or PM10, are around 60 percent of those in Beijing and a fraction of readings in New Delhi, the world's most polluted capital.
For more than a week now, the PM10 readings have been at dangerously high levels of over 80 microgrammes per cubic metre of air particles, reaching 146 microgrammes/m3 last Thursday.
Other parts of France are also being choked by smog.
Officials in the southeast Rhone valley region said they would introduce measures to restrict car use from Friday to combat the problem in the city of Lyon.