Paris is more prone to smog than other European capitals because of France's diesel subsidies and its high number of private car owners. A week-long spell of unseasonably warm, sunny weather has recently exacerbated the problem.
Under the scheme, drivers may only use their cars on alternate days, according to the odd or even numbers on their licence plates. Free public transport, including cycle and electric car-sharing schemes, was introduced last week as a visible haze hung over Paris streets.
"Our core objective is to ensure public safety because we want to end this pollution," Environment Minister Philippe Martin said yesterday, warning that the air quality was likely to worsen today.
Last week, European Environment Agency (EEA) figures for Thursday showed there were 147 microgrammes of particulate matter (PM) per cubic metre of air in Paris, which compared with 114 in Brussels, 104 in Amsterdam, 81 in Berlin and 79.7 in London.
Political opponents and car associations criticised the decision, saying it would be tough to police, and accused the socialist government of conceding to pressure from its Green coalition partners ahead of local elections in late March.