Drivers who fail to switch off their engines when they are stuck in traffic could receive a £20 fixed penalty fine under a scheme being investigated by West Sussex County Council.
The penalty charge has been thought up to help cut pollution by preventing drivers from leaving their engines running unnecessarily.
Council officials said they would penalise motorists who refuse to turn their engines off.
The scheme could see fines being issued by traffic wardens in Shoreham where there are two air quality management areas, in the High Street and the A270. But it is understood that if it proves successful, it could be rolled out across the county.
In a statement, the council said the penalties could be applied in other urban areas where unnecessary exhaust fumes are linked to a deterioration in air quality, including town centres and at railway crossings.
A county council spokesman said: "We would stress that this is just an investigation at this stage. Air pollution is a particularly important health issue for our residents, particularly those with asthma, lung and heart conditions."
He said there would be exemptions for lorries with freezer units and others that have to keep their engines running.
© The Press Association 2008