The new law aims to protect children from secondhand smoke and to prevent future youth tobacco use.
The law applies to anyone smoking in the vehicle, not just the person driving.
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The law does not allow police to stop or detain a vehicle or its driver solely because someone is smoking with an underage occupant but a ticket could be issued if the vehicle is stopped for another traffic infraction.
A first time offender could be fined up to $100. A second or subsequent offense can cost the offender up to $250.
According to the American Lung Association, more than 41,000 people in the U.S. die from secondhand smoke exposure every year.
The law will go into effect on January 1, 2020.