French authorities on Monday put in place emergency traffic-limiting measures in Paris, as the City of Light and much of northern France suffers from a choking smog.
City mayor Anne Hidalgo had asked authorities to prevent one in every two cars from taking to the capital's streets and make all public transport temporarily free in a bid to drive down pollution.
Only vehicles with number plates ending in an odd number will be allowed to drive, though exceptions exist for vehicles like taxis, electric cars and ambulances.
Public transportation is to be free until at least Monday in Paris and its surrounding towns in an effort to force pollution down by coaxing drivers to give up their cars for a few days.
Similar emergency measures were last implemented almost exactly a year ago -- on March 17 -- during a particularly bad spike in the pollution levels.
On Saturday, air quality monitors predicted that concentrations of potentially dangerous particulates in the air could again go over the recommended maximum.
In Paris, authorities measure the concentration of particulates with a diameter of less than 10 microns -- so-called PM10 -- in the air to determine pollution levels.
These particulates are created by vehicles, heating and heavy industry, and include the most dangerous particles that measure less than 2.5 microns in diameter, which can penetrate deep into the lungs and the blood system and can cause cancer.
The safe limit for PM10 is set at 80 microgrammes per cubic meter (mcg/m3).
According to a 2011 World Health Organization report, the planet's most polluted city was Ahvaz in Iran with an average of 372 mcg/m3.
Beijing had an average of 121 mcg/m3, while Paris was measured at 38 mcg/m3.
PHOTO: Air quality monitors warn that toxic particulates in the air in Paris could go over the recommended maximum.
CREDIT: AFP Photo/Patrick Kovarik.