Shadow public health minister Luciana Berger said legislation and education "can work very well hand in hand" to ensure drivers do not smoke when there are children in the vehicle.
When asked if launching an educational campaign would be more effective than enforcing a ban Ms Berger told Daybreak, "I don't think it's either or."
"I think we need to look at education as a lot of people don't know that smoke within a car is 23 times more toxic than it is smoking in a building or a home, and that's obviously very important that people know that", she continued.
"But we also know that legislation alongside an education campaign can make a massive difference."
More top news
In the unexpected announcement on Monday, Mr Key said it was the "right time" to leave politics.
As the Government's Brexit appeal comes to the Supreme Court, here's a look at what you need to know.
According to local reports, the man was found by friends in their accommodation in Val Thorens resort in the Alps on Sunday morning.