By Phil Mercer
BBC News, Sydney
Authorities in Australia's most populous state, New South Wales, are to consider banning smoking in cars.
Smoking is linked to premature death
A parliamentary inquiry will look at the effects of passive smoking on passengers, particularly children.
Supporters of the proposal have admitted, however, that enforcing such a ban would be difficult.
Smokers in Australia have already been squeezed out of bars and restaurants, as well as some beaches and most other public places.
Now Fred Nile from the Christian Democratic Party has drawn up a private member's bill that makes cars the next target.
His idea will be investigated by a parliamentary committee.
The plan appears to have the support of the state government.
A spokesman said that tough action should be implemented to stop the small number of irresponsible people who smoked around youngsters in their cars.
There is, of course, the tricky issue of enforcement.
Ministers have conceded that applying any ban would be difficult.
Similar laws have been proposed in parts of the United States and Germany, but were rejected on privacy grounds.
The New South Wales government said there would have to be far more public debate before any new measures were brought in.
This type of smoking ban has been rejected by the state parliament on two previous occasions.
Supporters of the legislation have argued that research into the dangers of passive smoking has proved that change is urgently needed.