Smoking in cars carrying children could become a criminal offence before 2015, senior MPs have claimed.
The Parliamentary vote which gave MPs in England and Wales the power to bring in a ban was passed by 376 votes to 107.
MPs voted in favour of changing the Children and Families Bill, which means ministers now have the power to implement a ban.
Dr Penny Woods, chief executive of the British Lung Foundation, said: "The introduction of a law that would help prevent hundreds of thousands of children from being exposed to second-hand smoke in the car is now within reach.
"With both Houses of Parliament having made their support for the ban clear, the onus is now on the government to act accordingly and make this crucial child protection measure law at the earliest opportunity."
Bans on smoking in cars when children are present have already been implemented in some parts of the US, as well as Australia and Canada.
Dr Peter Carter, Royal College of Nursing chief executive said: “Along with a host of other health organisations, the RCN supports a ban on smoking in cars when there are child passengers present because we know that this can be hugely damaging to children’s health. We believe that the priority must be a child’s right to breathe clean air.
“The RCN was pleased to see so many MPs vote in support of a ban. We now want to see the measure become law as soon as possible.”