The House of Lords will today vote on a controversial Labour plan to ban smoking in cars while children are present.
Peers are set to vote on the issue this afternoon amid Labour calls for the creation of a specific offence amid claims the move will help save to lives.
Shadow public health minister Luciana Berger said the party intends to force a vote on an amendment to the Children and Families Bill in the House of Lords which it is tabling later today.
Should the move succeed the amendment would make it a legal obligation for drivers of private vehicles to fail to prevent smoking when a child is present.
Labour has said that if the vote does not pass the measure will be included in their election manifesto for 2015.
The measure has been strongly opposed by pro-smoking lobby group Forest who said the law would be difficult to enforce, was 'heavy handed' and disproportionate.
"We think legislation is a very heavy-handed way to tackle this problem. I don't think it is as big a problem as they like to make out. The vast majority of smokers wouldn't dream of lighting a cigarette in a car with a child," Forest director Simon Clark said.
"We don't need legislation that would be very, very difficult to enforce. Our concern is that what would happen is people will then say 'Let's have a ban on smoking in all private vehicles' so you could have a lone driver on his own in his own vehicle lighting a cigarette and he would be committing an offence.
"If you say 'Let's ban smoking in cars with children present', are you going to go on and try and ban smoking in the home if children are present?
"I think this would set a very bad precedent and lead to a lot of problems."
Ms Berger said that almost 500,000 children in England were exposed to potentially toxic levels of second-hand smoke in family cars every week.
"We know that children are particularly vulnerable to passive smoking. We know that a single cigarette can create concentrations of tobacco smoke in a car that is 23 times more toxic than in a typical house," she told BBC Radio 4's Today programme.
"Ministers have scrapped research that the last Labour government commissioned on smoking in cars with children. They have tried to kick this issue into the long grass and that's why Labour has brought forward these proposals today and why we are going to force the vote in Parliament."
Supporters of the ban also claim there is overwhelming public support for the measure, citing a YouGov poll from 2011 that found 78% of adults in Great Britain agreeing that smoking should be banned in cars carrying children younger than 18 years of age.
The poll also found that 44% agreed that smoking should be banned in all cars.
Shadow health secretary Andy Burnham also backed the call for a ban telling Sky: "When it comes to improving the health of children, we are duty bound to consider any measure that might make a difference."
Dr Penny Woods, Chief Executive of the British Lung Foundation - which has campaigned on the issue, said: “Research has shown that smoking in a car, even with the windows open or air conditioning on, can create levels of pollution that exceed World Health Organisation safe limits. Children are particularly susceptible to the dangers of this smoke, due to their smaller lungs and less-developed immune systems.
“This policy would help protect the health of nearly half a million children who are exposed to potentially dangerous concentrations of second-hand smoke within the family car every week. Labour are therefore absolutely right to act on the evidence and support it."