Smoking in a car where children are present will be made illegal in Wales after Assembly Members passed landmark legislation.
The new law will come into effect in less than four months' time and could see those breaking it hit with a £50 fine or even a court appearance.
AMs ratified the Welsh Government policy this evening by a majority of 46 to 1 at a key vote in the Senedd.
Critics say the move is too heavy-handed and fear it could pave the way for banning smokers from lighting up in their own home.
But Health Minister Mark Drakeford said there was compelling evidence against the dangers of second hand smoke and the new law would help protect children’s health.
He said: “Some people believe that opening the window of a car will help disperse smoke but in reality it simply blows back in. It causes a real and substantial threat to children’s health.
“Children cannot escape from the toxic chemicals contained in second-hand smoke when travelling in cars. They often don’t have a choice over whether or not they travel in cars and may not feel able to ask an adult to stop smoking.
“As with the existing smoke-free regulations, success will not be based on the number of enforcement actions that are taken but by how behaviour, attitudes and health outcomes change over time.”
Legislation banning smoking in enclosed public places was introduced in Wales in 2007. However, while the law covered public and work vehicles it did not extend to private vehicles.
The new regulations will make it an offence to smoke in an enclosed private vehicle when more than one person is present, at least one of whom is under the age of 18, and for a driver to fail to prevent smoking in such circumstances.
The Labour-controlled Welsh Government believes legislation is necessary after its public health campaign Fresh Start Wales failed to produce the results officials had hoped for.
A spokesman said: “Results of research carried out during the campaign show the number of children exposed to second-hand smoke in cars decreased; but regrettably they also show there remains a cohort of adults who continue to smoke in vehicles when children are present with 17% of children from poorer families more likely to report that smoking was allowed in their car compared to 7% of those from more affluent families.”
Several health and children's groups welcomed the new law.
Dr Mair Parry, Officer for Wales at the Royal College of Paediatrics and Child Health, said: “This is an historic vote and a victory for child health. There is growing medical evidence of the damage cigarette smoke can do to children – including asthma, chest infections, ear problems and cot death – and frighteningly smoke in cars can be up to 11 times more concentrated than in a smoky bar.”
The British Lung Foundation also described the move as “a tremendous victory” for the “thousands of children being exposed to second-hand smoke every week”.
However, while the overwhelming majority of AMs voted in favour of the legislation there was concern in the Siambr among some opposition AMs.
Welsh Liberal Democrat leader Kirsty Williams said the issue of “banning behaviour” was a complex one.
“At what point do we say that people cannot smoke in front of children within their own home?”, she added.
And party colleague Peter Black said he would not be voting in favour of the law.
Pro-smoking group Forest branded the new law as “heavy handed”.
A spokesman said: “The overwhelming majority of smokers know that smoking in cars is inconsiderate and don't do it.
"Education has to be better than legislation but the government prefers gesture politics and the big stick.”
The ban will come into effect on October 1 - the same day similar measures are being implemented in England.
Joseph Carter, head of the British Lung Foundation in Wales, said: "Today's vote marks a monumental triumph for children's health in Wales. After years of campaigning on this issue, we are glad that common sense has prevailed and that, as of October 2015, children in Wales will no longer be subjected to toxic smoke in the small confines of a car.
"With almost half a million children being exposed to second-hand smoke in the family car every week in the UK, it is right that Wales is joining England in supporting such a ground-breaking public health measure. We now look to our neighbours in Scotland and Northern Ireland to offer their children this same protection."