Drivers in the centre of Bath could be ordered to turn their engines off if they are parked up for more than two minutes under new plans to target pollution.
Bath and North East Somerset Council is launching a campaign encouraging motorists to think carefully about their exhaust fumes, with flyers being distributed to coach, bus and taxi drivers.
It is also applying for powers under road traffic regulations which would give traffic wardens the powers to take enforcement action against those who refuse, meaning drivers could be fined.
Cabinet member for transport Councillor Roger Symonds (Lib Dem, Combe Down) said it was an easy way to tackle the high level of carbon emissions in the centre.
He said: "It is simple common sense. Exhaust fumes pollute the air with a range of harmful chemicals, like sulphur dioxide, formaldehyde, and benzene. These cause health problems like asthma, heart disease, and lung cancer. In our unique heritage city, the fumes deposit particles on buildings which result in the corrosion of Bath stone.
"The council wants drivers to play their part in combating unnecessary exhaust fumes."
The initiative does not apply to vehicles in stationary traffic, and is targeted at parked vehicles with their engines running. It has already won the support of local bus companies, which have said they are happy to comply.
Managing director of Bath Bus Company Martin Curtis said: "We already follow an engine switch-off policy which is rigorously enforced, and have no difficulty therefore in supporting this initiative."
Tim Jennings, from Somerbus, said its drivers tried to switch engines off as much as possible while in Bath.
Bath's biggest public transport provider First is preparing to introduce technology which shuts off engines when buses are stationary for a set period of time.
The firm's business manager Richard Lewis added: "To further support programmes like this we ask all of our drivers, when loading passengers at the start of their journeys to only start the engine once all the customers are on board and they are ready to leave. In Bath we enforce the latter through random spot checks within the bus station."
