In addition, at least 127,700 children aged under-14 are exposed to second-hand smoke in their homes.
"Second-hand smoke exposure has been stated as being responsible for about 350 deaths in New Zealand each year," Dr de Wet said.
"In children ... it would play a role in exacerbating things like asthma or increasing the risk of respiratory illnesses like respiratory tract infection."
Mrs Turia said the proposed ban was about "ensuring that our tamariki are not exposed to second-hand smoke".
"It is a policy that we have seen implemented in Queensland, Australia, and I have asked my officials to look into this and how this may work here in New Zealand."
A Parliamentary bill increasing the price of cigarettes to more than $20 a pack over the next four years was passed this year.
The legislation will raise tobacco excise tax by 10 per cent each year, from 2013 to 2016.
The tax hikes are part of a raft of measures designed to make New Zealand smokefree by 2025.
In July, tobacco displays in retail outlets were banned and proposals for plain packaging of tobacco products are being considered by the Government.
"If we want to save lives we need to look seriously at all the options and that is what we are doing," Mrs Turia said.
Plunket says any exposure to smoke is harmful for children.
"Second-hand smoke makes children sick. It flattens the little brushes that sweep and clean their airways," clinical advisor Allison Jamieson said.
"Because children breathe faster than adults and have smaller bodies, they take in a higher dose of smoke than adults.
"In confined spaces, such as cars, they are unable to move away from smoke and are trapped with its poisons."
Michael Coulhoun of Action on Smoking and Health said young children were most vulnerable to the effects of smoking. "Unlike the restaurant and bars which had a high level of smoking and that's now been corrected, there's still an impact in cars.
"We think it will reduce the harm on smoking and ... the emphasis should be on young children, whether it's passengers under a certain age - certainly under 16."
High Risk
Children exposed to second-hand smoke are at increased risk of:
Premature death.
Sudden unexpected death in infancy (cot death).
Chest infections.
Ear problems.
More severe asthma.
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Source: 2009 NZ Tobacco Use Survey