As of April 1, Nova Scotia will become the first province in Canada making it illegal to smoke in motor vehicles with anyone under 19 inside.
The amendment was passed by the legislature on Thursday.
"This legislation is another important step in protecting the health of all Nova Scotians," Barry Barnet, minister of health promotion and protection, said in a news release on Thursday.
"Children and young people are susceptible to the effects of second-hand smoke, especially in an enclosed space such as a car."
Barnet said the amendment reinforces what the majority of Nova Scotians are already doing.
"For others, we hope it will serve as an opportunity to learn about the health risks associated with second-hand smoke," he said.
In November, the town of Wolfville, N.S., became the first district in the province to pass a municipal bylaw banning the practice.
Move also underway in other provinces
Other provinces have also indicated plans to ban smoking in cars with children passengers.
The British Columbia government promised a ban in its recent throne speech and New Brunswick and Manitoba are both considering one.
Ontario Premier Dalton McGuinty said in early March that his government would also be introducing legislation this spring to prohibit the practice.
Doctors say the risks to children from exposure to second-hand smoke include respiratory illnesses, middle ear disease, lower respiratory tract infections and sudden infant death syndrome. They say exposure can also lead to increased incidences of cancer and heart disease in adulthood.