You probably don't know any children over the age of 6 who are still riding around buckled into booster seats — but you soon will.

That's because child passenger safety groups have made lawmakers and the public more aware of the safety gap for children who have outgrown infant car seats but are not yet big enough to benefit from the protection offered by adult safety belts.

Forget the old rule of thumb that says your child could abandon his or her booster seat when the scale hit 40 pounds. Most children are not grown enough to properly wear adult seat belts until they are more than 4 feet 9 inches tall and weigh more than 80 pounds, according to the Partners for Child Passenger Safety (PCPS), a joint venture of State Farm Mutual Insurance Co. and the Children's Hospital of Philadelphia.

"Seat belts are designed to fit the [average] adult male," says Dr. Flaura Winston, the principal investigator for PCPS. "Just like you wouldn't give your child your raincoat to wear, you shouldn't give him your seat belt."

Startling statistics

Child passenger safety statistics should be enough to convince any parent of the importance of booster seats for children who are between infant car seats and adult safety belts, according to Winston. "Motor vehicle crashes remain the leading cause of death and acquired disability in children over age 1 in the United States," she says.

Equally sobering are statistics from the National Highway Traffic Safety Administration and PCPS that show:

• Among children ages 5 to 9, more than 500 are killed and 95,000 are injured annually in motor vehicle accidents.

• Children ages 2 to 5 who use adult seat belts are 3.5 times more likely to suffer significant injury and four times more likely to suffer head injury when compared to children in the same age group who use car or booster seats.

• Nearly 40 percent of 2- to 5-year-olds and 16 percent of 3-year-olds use adult seat belts when they should be restrained in a height/weight-appropriate car seat.

• By age 4, most children were using adult seat belts rather than a car seat or belt-positioning booster seat.

• Eighty-three percent of children between the ages of 4 and 8 use adult seat belts that are inadequate to protect them in a crash.

• More than 90 percent of children between the ages of 4 and 8 who were seriously injured in crashes between Dec. 1, 1998, and Sept. 1, 2000, were not in booster seats.

Nationwide safety trend

Lawmakers and parents of children age 4 and older are beginning to get the message, Winston says. California's new booster seat law — similar to those already enacted in Arkansas, New Jersey, Oregon, Rhode Island, South Carolina, and Washington — requires that children must be secured in a child safety seat or car booster seat until they are 6 years old or weigh 60 pounds. This is an expansion of the previous law that mandates children younger than 4 or who weigh less than 40 pounds to ride in a safety seat. The first offense for breaking the law (which takes effect on Jan. 1, 2002) is a fine of $100. Each subsequent violation will cost $250.

Experts in the child passenger safety community are also beginning to focus more on fit rather than strict height or weight standards in their assessment of whether a child still needs a booster seat. SafetyBeltSafe USA's Web site provides detailed information on types of booster seats and how to properly install them.

In light of the climate of uncertainty following the terrorist attacks on New York City and Washington, D.C., Winston says using the appropriate car or booster seat is an easy thing every parent can do to protect their children. "People aren't flying or taking the train as much, so that means they are driving more," Winston says. "It's not only safer for these kids to be in booster seats, but it's more comfortable as well. Kids like to be able to sit comfortably and be able to see out the window."