Charges have come into force for drivers entering Birmingham's Clean Air Zone (CAZ).
The zone was officially launched on 1 June, but there was a two-week delay to charges to give motorists "time to adjust".
From 00:00 BST on Monday, drivers of a vehicle not meeting emission standards, and without an exemption, will face a daily fee.
It comes as a fault suspended tram services until the end of Monday.
City Conservatives had called for CAZ charges to be further delayed due to the issue.
All roads inside the A4540 Middleway ring road fall into the zone, but the circular route itself is not included.
At the launch of the scheme, the local authority confirmed it would pause payments to allow more people and organisations to apply for an exemption or financial incentive.
The daily charge for vehicles that do not meet standards is £8 for cars, vans and taxis, or £50 for HGVs and coaches, unless a valid exemption is in place.
The zone is enforced using Automatic Number Plate Recognition (ANPR), which records the registration plates of vehicles travelling within the ring road.
Anyone who fails to pay within six days after entering the zone faces a £120 fine.
Waseem Zaffar, Birmingham City Council's cabinet member for transport and environment, said: "The Clean Air Zone will help us to address the single biggest environmental risk to public health and I have been clear from the beginning of the scheme that we wanted to make its introduction fair and reasonable."
About 75% of cars will not be subject to the charge, but Mr Zaffar urged drivers to check their vehicles online before travelling.
The local authority has previously said air pollution contributed to 900 premature deaths a year in the city and it faced a £60m fine if it failed to implement the zone.
Source: BBC