Hundreds of police will monitor traffic in Paris on Monday after pollution levels prompted the French government to impose major restrictions.
Only motorists whose cars have odd-numbered registration plates will be allowed to drive.
On Tuesday, if the restrictions remain in place, it will be the turn of those with even-numbered plates.
Ministers acted after air pollution exceeded safe levels for five days running in Paris and surrounding areas.
The smoggy conditions have been caused by a combination of cold nights and warm days, which have prevented pollution from dispersing.
The measure has been tried once before, in 1997. Paris air quality monitoring body Airparif says it had a noticeable impact on improving air quality, although critics have disputed its findings.
Motorcycles will also be covered by the ban, which runs from 05:30 (04:30 GMT) to midnight on Monday. There are exceptions for electric and hybrid vehicles, and for cars carrying three or more passengers.
Those flouting the restrictions will face a small fine although there will be free parking for those with number-plates ending in an even number.
Delivery companies are already complaining of lost income, BBC Paris correspondent Hugh Schofield says. Politically the stakes are high, with elections for Paris mayor due to start next week.