A study looking into banning all petrol and diesel vehicles from the centre of Oxford has been launched.
The city and county councils have jointly commissioned the £30,000 study in a bid to reduce air pollution.
If agreed, the zone could be introduced from 2020, starting small and expanding as technology develops.
The city centre has been a low emission zone since 2014, requiring all local bus services to use low-emitting vehicles.
City council board member John Tanner previously branded the idea “ridiculous”, but now says he is “thrilled” the study is taking place.
He added: “Air pollution has a significant impact on the health of residents and visitors to Oxford.
“Our vision is to create a city centre that people can live and work in without worrying about how vehicle emissions will impact on their health.”
But speaking in 2015 he said the city council would not support “a blanket ban” because “ordinary” cars were not responsible for pollution.
The Road Haulage Association also called the proposals “unworkable”.
A spokesman for the county council said the ban would initially only apply on a small number of roads, and the timescales would change if technology was not advanced enough.
Last year, Oxford was featured in a report by the World Health Organisation as one of 10 cities with unacceptable levels of pollution.
And European Union targets for air pollution are currently being breached at 32% of 75 locations monitored across Oxford.