However, the fine would be waived if the smoker enrolled in a cessation program to quit. And only warnings would be given during the law's first year.
"I don't take lightly telling the public what they can do in their cars unless it is for a very important health or public safety purpose like the one we have here today," Arent told the committee.
Since a car is such a small enclosed space, contaminants from secondhand smoke quickly rise to unacceptable levels and can cause a lifetime of damage to children's lungs, Arent said.
During an earlier press conference, Kevin Nelson, a pediatrician at Primary Children's Medical Center and chairman of the Coalition for a Tobacco Free Utah, described HB13 as common sense that puts children first.
In 2010, the Utah Department of Health found that of Utah's 65,000 children suffering from asthma, 16,000 were subjected to secondhand smoke while riding in cars.
"Let's be clear," Nelson said. "The worst place for a child to be around secondhand smoke is in a car."
Dalane England of the Utah Eagle Forum asked members of the committee to consider leaving the decision to parents.
"I don't really believe this bill is about cars or smoking," England said. "This bill is about who is the best parent; it's about our freedom versus our security."
Rep. Brian Greene, R-Pleasant Grove, and Rep. Michael Kennedy, R-Alpine, voted against the measure.
HB308: Restrict smoking in work vehicles
Rep. Lee Perry, R-Perry, is sponsoring legislation that would add vehicles to the list of workplaces where smoking is banned under Utah's Indoor Clean Air Act. It would apply to company vehicles that are shared by employees, but not to an owner-operator of a business who is the sole user of the vehicle.