A study, commissioned by Bristol City Council, may lead to people who own diesel cars being charged should they drive into the city.
The study follows a report to councillors, which claim that 40% of poisonous vehicle fumes come from diesel cars.
The report also stated that up to 300 people a year die from the city's high air pollution.
The areas in the city highlighted in the report as the worst are:
Rupert Street - with the most dangerous air
Upper Maudlin Street - outside the Children's Hospital - has not had safe levels since records began in 2005.
Councillors, who are legally responsible for making sure pollution is brought down to acceptable levels, are considering one of the following zones to be made chargeable for drivers with diesel cars:
just the city centre, which is the smallest area:
a larger area including parts of the M32, Gloucester Road and A37 and A37; if they feel the first option would not tackle the problem:
the largest area, stretching into South Gloucestershire:
Although a new green biogas bus was launched today, Tuesday 8 August, Bristol only has up until March 2018 to get its levels down, despite some roads never being close to the legal limits.
Watch Robert Murphy's full report below: