A 24-hour traffic-regulating scheme in Paris that aims to halve the day's emissions from road vehicles has been launched amid a crackdown on rocketing air pollution in the French capital.
Police said that on Tuesday only vehicles with an even-numbered licence plate will be allowed to use the roads in Paris and its nearest suburbs.
Some 140 checkpoints around the city will root out any odd-numbered cars and turn them back.
All day, public transport will be free to encourage its use.
The initiative is part of mayor Anne Hidalgo's push to fight Paris' exceptionally high pollution and make the city more friendly for pedestrians and cyclists.
The scheme has been implemented twice before, in 2014 and 2015, sometimes affecting odd-numbered vehicles and sometimes even-numbered ones.