The Ontario government plans to introduce legislation this spring to ban smoking in cars where young children are present.

Premier Dalton McGuinty announced in Toronto on Wednesday that the law will be brought in for the spring session of the legislature, which is scheduled to begin March 17.

"We know that this is harmful to children," McGuinty said. "We need to do everything we can to keep our children safe and healthy."

Children exposed to second-hand smoke are more likely to suffer sudden infant death syndrome, asthma and cardiac disease, the premier said.

McGuinty said that being exposed to one hour of second-hand smoke in a car is the same for a young child as smoking an entire pack of cigarettes.

Ontario doctors welcomed the decision. The Ontario Medical Association said in a news release that it has been calling for such a ban since it released a report on the issue in 2004.

Dr. Janice Willett, president of the OMA, said Ontario doctors have tried to educate the public about the dangers to children of second-hand smoke in vehicles and build public support for a ban on smoking in cars carrying children.

"We have seen tremendous leadership from the province and are looking forward to seeing children benefit when this legislation is put into action," she said.

The premier said he was originally reluctant to ban smoking in cars carrying children, but was swayed by arguments made by his minister of health promotion and a backbencher.

He had promised last week that his Liberal government would take another look at the idea. He said Wednesday he hopes the opposition parties will pass the legislation quickly.

But he acknowledged that some drivers may see the ban as an invasion of their privacy.

Premier looks to balance rights, responsibilities

"You've got to continue to look to ensure you are striking an appropriate balance between the rights of individuals, the right to exercise personal freedoms and liberties, and our collective responsibility as a society to protect the interests of our most vulnerable," he said.

McGuinty declined to specify how the province would define child in terms of age or the amount of the fine to be levied against the driver.

In a private member's bill introduced by Liberal MPP David Orazietti in December 2007, which called for a similar ban, a child is defined as anyone under 16 and the fine for drivers who violate the ban is $200. The bill has passed first reading.

McGuinty said the government will introduce its own bill but it will not go beyond the scope of the private member's bill. 

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.

Dr. Suzanne Strasberg, board chair of the OMA, said the concentration of smoke in cars can be up to 60 times greater than the concentration of smoke in a room inside a house.

"The need for such a ban is undeniable," she said.

Nova Scotia banned smoking in cars where children are present in January and the B.C. government pledged in its recent throne speech to enact a similar ban. New Brunswick and Manitoba are also considering bans.

With files from the Canadian Press