Paris Limits Car Use in Face of Heavy Smog

(Jacques Brinon/AP Photo)

Paris may be the City of Lights, but things haven't been so luminous since a spell of thick smog has nestled over the French capital's usually stunning skyline.

In response to a sharp rise in pollution levels last week, the French government has announced plans to limit the number of vehicles allowed on Parisian streets, reported French media, including France 24. On Monday morning, the city will be adopting a system of "alternating traffic," allowing only vehicles with either odd or even license plate numbers to drive on alternate days.

A statement from the office of French Prime Minister Jean-Marc Ayrault said the smog situation had improved slightly on Saturday, but a decision on whether to extend the traffic limiting measure will be made on Tuesday, when forecasters expect pollution levels to rise again.

"The prime minister is aware of the difficulties that this may cause to the everyday lives of Parisians," the statement said, according to French media, "but this is a necessary measure."

The decision came amid the worst case of pollution the country has seen since 2007.

A consecutive period of warm daytime temperatures followed by cool, dry nights is thought to be the trigger for the pollution spike. The conditions, coupled with a shortage of wind and rain in the area, do not allow pollution particles to disperse fast enough, pollution watchdog group Airparif told France 24.

In the Ile-de-France region, which includes Paris, officials measured 180 micrograms of particulate matter per cubic meter of air on Friday, which far exceeded the 80 micrograms maximum alert level.

Parisians were granted free access to public transport over the weekend, including free rides on Paris's bike share program, in an effort to reduce the smog.

Authorities also advised "children and sensitive people to avoid doing sports and follow their medical treatment" during the spell, according to flashing messages displayed throughout the city.

ABC News' Colleen Curry contributed to this report.