Vehicles with odd-numbered licence plates were banned from driving in Paris and the Ile de France region on Thursday, in an alternating restriction that meant even-numbers were banned on Wednesday.
But, after Tuesday's ban, which also covered odd-numbered plates, was widely ignored, top Paris security official Marc Meunier appealed to motorists to be more civic-minded from now on.
"There really must be greater awareness on the part of our fellow citizens, that everyone feels that this affects them," he said on Thursday, claiming that the measure could reduce the number of vehicles on the roads by 30-40 percent and pollution by the same amount.
On Wednesday the measure was "pretty well enforced", Meunier said.
Polluton reduced in 2014
Pollution was reduced by 6-10 percent when the ban was briefly enforced in 2014, with a 20 percent fall at rush hour.
This week's pollution is the worst and the longest for 10 years, according to the Airparif monitor.
Air pollution causes 42,000 deaths a year in France and costs 100 billion euros, according to report to the Senate.
Lyon joins traffic ban
The central city of Lyon and neighbouring Villeurbanne are to enforce a similar ban on Friday, the first time they have ever done so.
The heavy pollution, caused by a combination of heating and traffic emissions with the effects of an anticyclone that has covered much of western Europe, has hit a number of other French towns and cities - Grenoble, Amiens, Rouen, Dunkirk, Calais, Lille, Rodez and urban areas in the Alps and the Pyrenees.
Weather forecasters predict an easing off at the weekend but a return to the same conditions for the following fortnight.