It comes after health campaigners warned half a million children are breathing in their parents' second-hand smoke every week.

Smoking in cars carrying children has been made illegal in England and Wales - with £50 fines for parents who break the law.

It's been confirmed after Welsh politicians overwhelmingly backed a ban today, with 46 voting in favour and just one against.

England has already outlawed smoking in front of children in cars and the ban will take effect in both nations on October 1.

It comes after the Mirror revealed how a two-year-old boy will be put up for adoption because his parents are heavy smokers.

One nurse in the case complained the 'squalid' conditions - including a 'visible cloud' - made her 'gag and cough'.

Health campaigners have warned half a million children are breathing in their parents' second-hand smoke every week.

Cars are worse than houses because they're such confined spaces - and inhaling toxic chemicals affects young children more than adults.

Even with a window open, the 4,000 chemicals in cigarette smoke can stay in the air for 4 hours and trigger asthma and pneumonia.

The NHS claims it's twice as likely for babies with smoking mothers to suffer cot death - and passive smoking can also trigger meningitis.

The campaigners are now calling on Scotland and Northern Ireland to pass the same law, which will apply to all those with passengers under 18.

Welsh politicians voted overwhelmingly in favour of a ban today after a debate in the National Assembly, WalesOnline reports.

Welsh Government Health Minister Mark Drakeford said: "Children cannot escape from the toxic chemicals.

"They usually have little choice over whether or not they travel in cars and are not in a position to require an adult from refraining from smoking."

“The underlying purpose of these regulations is not to introduce a great spike in enforcement actions but to... change culture.

“It will protect children from entirely avoidable harm.”

There was support from Welsh nationalists Plaid Cymru, the Welsh Conservatives and the Welsh Lib Dems.

Only Peter Black of the Lib Dems, who had a free vote, opposed the ban - claiming it could be a slippery slope to banning smoking in private homes.

But Joseph Carter, head of the British Lung Foundation in Wales, said: “Today's vote marks a monumental triumph for children’s health.

"After years of campaigning on this issue we are glad that common sense has prevailed."