The new law aims to protect children from secondhand smoke and to prevent future youth tobacco use.
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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.
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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.