The first step in a plan to tackle Milan's smog problem by making the worst polluters pay got under way on Tuesday.
Under the scheme, drivers will eventually have to buy a ticket to enter the city centre, the cost of which will vary depending on the vehicle.
The more pollution the vehicle emits, the higher the price.
Forty-three entry points to the city's historic centre are now active, complete with cameras, and connected to a central computer able to identify cars by the licence plate.
This first stage of the scheme entails a series of technical tests on the equipment, and is intended to iron out teething problems.
If the pilot scheme goes smoothly, a full version of the initiative will be launched on January 2 next year.
Drivers will then be able to purchase an "Ecopass" - either a day ticket or a multi-day pass - in advance or up to 24 hours after entering the centre. The pass will be available in branches of two Milanese banks, online or from a local call centre.
The project, part of a wider 3.5-million-euro funding deal signed with the central government last month, has raised some concern in Milan, although polls indicate support for the underlying goal.
The Northern League, a centre-right party on the city's municipal council, has fiercely contested the idea, which also involves periodic closures of Milan's historic centre to all traffic.
"We'll wait and see what happens during this pilot phase but we're convinced that other methods should be used to deal with Milan's smog problem," said Matteo Salvini, the party leader on the local council.
"Milan deserves a referendum on the Ecopass, as well as on closing the city centre to cars".
Earlier this month, the Northern League set up 50 stands around the city, asking more than 20,000 residents their opinion of the plan.
Three quarters of those questioned said they were in favour of closing the city's historic centre.
The Ecopass scheme was supported by 44% of those questioned, while 48% were opposed.
Another poll by the national weekly Panorama reached similar conclusions after questioning inhabitants across the region of Lombardy.
Half of respondents thought something should be done but weren't convinced the Ecopass would solve the problem. Thirty-eight percent thought it would, while 11% said they didn't know.
In general, Milan's residents were more positive about the Ecopass than those living in other parts of Lombardy. While 47% of Milanese said they personally supported the Ecopass and 45% were opposed, this compared to 41% in favour and 50% against elsewhere in the region.
The scheme is part of a wider drive to improve the city's air pollution and transport. New parking restrictions will take effect at the start of next month, while 15 kilometres of bus lanes will be in operation by mid-November.
The council has also said it is reconsidering previously shelved plans to extend three of the city's metro lines.
