A ban on smoking in cars where children are present will come into effect on New Year's Day.
This will be enforced by gardaí and carries a fixed penalty of €100.
There will be tougher penalties, of up to €1,000, for failing to stop or providing inaccurate details to gardaí.
A recent survey indicated that almost one in five children are exposed to smoke in cars.
That smoke contains more than 4,000 chemicals, about 50 of which are cancer-causing.
The law, which does not apply to e-cigarettes, comes into effect on 1 January 2016.
Minister for Children and Youth Affairs James Reilly said the ban is being introduced to bring about a culture change so that people do not engage in the activity.
Speaking on RTÉ’s News at One, Minister Reilly said that the ban applies to anyone who is smoking in a car in a public space with a child present.
"It absolutely applies to anybody who has a child in a car in a public place,” he said.
"What we are seeking to do is to highlight it, to underscore it with law and to bring about a culture change where people just won't engage in this activity further because it damages children's health."
Earlier, Senator and Oncologist Professor John Crown said the primary purpose of legislation banning smoking in cars with children is to educate people about the dangers.
Speaking on RTÉ's Morning Ireland, Prof Crown said the new regulations were not about sanctioning and fining people.
Prof Crown said there are more toxic emissions within the car during the time it takes to smoke one cigarette, than what comes out of the exhaust of the car.
"A child who is in a car with a smoker for one hour is exposed to approximately the same level of hazardous smoke as a firefighter is if they're fighting a bush fire and it is equal to many, at times, the amount of exposure that somebody would have in a pub.
“So all of the risks of passive smoking are amplified in the small confines of a car," Prof Crown added.
Action on Smoking and Health Ireland has welcomed the legislation, saying it will "help to ensure our children are protected from the harmful effects of passive tobacco smoke".