There are enough reasons to ban smoking in car as the prime reason is the health of children who are travelling in it. There are number of evidence that second-hand smoking from vehicles affect children's health to a considerable limit.
Dr. Ray Pawson of the University of Leeds School of Sociology and Social Policy in the U. K. and his co-authors have found that concentration in chemicals in second-hand smoke inside a car is more harmful.
Due to closed environment inside cars second-hand smoking is more vulnerable. Besides, children are more susceptible to second-hand smoking than adults. According to the review by the team, "There is an abundance of evidence to help legislators decide on this matter, but that evidence always consists of conditional truths."
However, at the present scenario, most of the Canadian provinces has a strict ban on smoking inside a car. The only exceptions are Newfoundland and Labrador, Alberta and the Northwest Territories whish do not ban the practice though there are some local initiatives by various municipalities.
The Quebec Ministry for Health and Social Services informed that various options are under consideration but it would keep away from making any rigid comment on the subject. The first province that banned smoking in cars with children 2008 was Nova Scotia.