Motorists in Paris were gearing up for a radical change to their commute on Monday after the government introduced alternate driving days to alleviate the veil of smog that has hung over the city for days.

On Saturday evening the government announced that only cars and motorbikes with registration plates ending in an odd number would be allowed in the greater Paris region on Monday.

Electric and hybrid vehicles, and cars with at least three people aboard, will be exempted from the measure.

On Sunday, Paris police said around 700 officers would be deployed to screen cars.

The announcement came after five consecutive days of harmful levels of particle pollution over northern France and parts of the south—east.

The City of Paris had already made public transport free for the weekend in an effort to get cars off the street.

Prime Minister Jean—Marc Ayrault said he was “aware of the difficulties” that the alternate driving plan would cause for commuters.

“But this extra measure is necessary,” he said in a statement, calling on motorists to show a “spirit of responsibility and civic—mindedness.” Depending on air quality forecasts, the measure could be continued Tuesday, in which case the restriction would apply to cars with plates ending in an even number.

The last time France grounded cars over pollution was in 1997. The measure was highly unpopular.

Motorists took to news websites and social networks to voice their disapproval of the measure.

“To think that the Paris public transport system, which is heaving at peak hours, can absorb the flow of those who, one day out of two, have the wrong plate, is a rare (kind of) stupidity,” one reader remarked on the website of Le Nouvel Observateur.