Patrick signs booster seat law

Legislation requires the car safety device for children under 8

Children will have to ride in either car seats or booster seats until they turn 8 years old under a new law signed yesterday by Governor Deval Patrick that brings the Bay State into line with federal motor vehicle safety standards.

"This is a common-sense piece of legislation that will go a long way in ensuring more children will be protected on the road," said Cyndi Roy, a Patrick spokeswoman.

The purpose of a booster seat is to position the safety belt across the child's waist and shoulder, rather than halfway up his or her midsection or neck. Children at least 4 feet 9 inches tall would be exempt from the child-seat requirement.

"Because adult safety belts ride too high up on children's neck or waist without the use of a booster seat, a minor car accident can cause a major injury to a child," said state Senator Steven Baddour, a Methuen Democrat, who sponsored the legislation. "This new law is great news for children's safety going forward in the Commonwealth."

The new law, which carries a $25 fine, will go into effect in mid-July.

Under the current law, children are required to be in car seats until they turn 5 or weigh at least 40 pounds. The new law replaces the weight requirement with a height requirement.

While some safety-cautious parents have been buying booster seats for children between the ages of 5 and 8, many parents don't use them, completely unaware of their benefits, said Arthur Kinsman, director of government affairs for AAA Southern New England, who has been advocating for the booster-seat law for the past seven years.

Kinsman said the use of booster seats reduces the risk of injury for children by 38 percent compared with children using an adult seat belt and by 59 percent compared with children who don't wear a seat belt.

Installing a booster seat is easy, Kinsman said. "It's like sticking a glorified phone book underneath a kid," he said.

The booster seats, he said, can cost as little as $15 at some major department stores, although more extensive ones can cost much more.

Thirty-eight states have booster seat laws, up from four just seven years ago. Massachusetts will be the only state in the Northeast to have such a law.

The new regulation will bring some financial perks to the state. The federal government is providing $25 million over the next four years to states that adopt enhanced booster seat laws, and the new law would make Massachusetts eligible for up to $750,000 in federal funds.

James Vaznis can be reached at jvaznis@globe.com.