However, that has now come to an end, meaning charges will now be enforced.
Every road inside the A4540 Middleway ring road is included.
The Middleway, which encircles Birmingham city centre, is not included, but the A38 and its tunnels are, along with areas such as New Street, Digbeth, Lee Bank and Ladywood.
Affected postcodes include B1, B10, B12, B15, B16, B18, B19, B2, B3, B4, B5, B6, B7 and B9.
More than 300 signs have been put up around the area to tell motorists when they are entering the zone, while 67 Automatic Number Plate Recognition cameras will read registration plates of vehicles entering and leaving.
Those with high-polluting vehicles will have to pay due to the higher levels of nitrogen dioxide emitted.
That includes anyone with diesel vehicles built before 2015 and petrol models built prior to 2006, along with electric, hydrogen fuel cell and hybrid electric vehicles.
The charges are:
Cars, taxis and vans – £8
Buses, coaches and HGVs – £50
The fees renew at midnight each day (so if someone enters the zone at 11.50pm and leave 20 minutes later at 12.10am, they will have to pay for two days). However, motorists can enter the zone as many times as they like each day, and not have to pay for each journey.
There is no discount for entering each day, meaning a car driver could pay up to £40 per five-day working week, while lorry drivers could face a £250 bill over the same period.
The charges operate seven days a week, 365 days a year.
It will be the driver’s responsibility to pay as alerts will not be sent out (the only warning is from roadside signs).
Motorists can pay on the Government clean air zone website or by calling the Government’s clean air zone team on 03000 298888.
Drivers have a 13-day payment window; six days before travel, on the day, or six days after.
Anyone who doesn’t pay within that time frame faces a £120 fine, which will be reduced to £60 if paid within 14 days of it arriving in the post.
Money raised will go towards funding sustainable transport measures, such as walking and cycling routes and public transport.
Emergency and armed forces vehicles won’t have to pay, along with some commercial vehicles operating at businesses within the zone. City centre firms can also apply for temporary permits for a maximum of two vehicles.
Some residents inside the zone, or commuters travelling in, can apply for a temporary exemption and/or financial incentives if they earn under £30,000 a year.
People travelling for certain medical appointments can also apply for an exemption.