Safety research carried out by Holden and the Monash University Accident Research Centre (MUARC) stresses the importance of restraining children who are between five and 10 years of age in belt-positioning child booster seats until the adult seat belt alone fits them correctly.

The research project focused on five to 10 year-olds because the vehicle occupant fatality and injury rates for these children are higher than for younger children.

Between 1998 and 2002 - according to MUARC - an average of 148 children aged 10 years and younger were killed or seriously injured each year in car crashes on Victorian roads.

Of these, 62 per cent were aged five to 10 years; 32 per cent were aged one to four years; and six per cent were under 12 months of age.

The Holden/MUARC research project was based on a series of crash simulations conducted at Holden's proving ground using a crash test dummy representative of a six year-old child. The tests showed the dangerous forward movement that can occur during a crash when a child is wearing the car's seat belt alone, rather than being properly restrained in a booster seat.

Holden Innovation Chief Engineer, Dr Laurie Sparke, said the research provided further confirmation that using booster seats can help to prevent or lessen serious injury to children in a crash.

"While the majority of parents now use a baby capsule and forward-facing child seat as a matter of course for younger children, many may not realise that restraining their five to 10 year-olds with seat belts alone can be an unsafe practice. The car's seat belts are designed to protect adults, not children," Dr Sparke said.

In preparation for the tests, Holden engineers positioned the dummy on the rear seat to imitate the way that children sit when restrained by adult seat belts alone.

In frontal crash testing, the dummy's hips slid forward on the seat so that the lap belt rode high on the soft abdomen, rather than on the lower hips and upper thighs, where it should have been. The dummy also lurched forward, demonstrating the risk of injury to a small child riding improperly restrained without a booster seat.

"Belt-positioning booster seats are the best way to help protect older kids, but based on international research, it is likely that only 12 per cent of children who should be restrained in booster seats are actually using them," said Dr. Judith Charlton, Research Fellow at the Monash University Accident Research Centre.

"MUARC recommends that children who are over 100 centimetres in height and more than 18 kilograms in weight should be correctly secured in belt-positioning booster seats until they reach the stage where adult lap and shoulder belts fit them properly. This is usually when they're between eight and 10 years old, approximately - although there's no ‘right age' for this, because it's dependent on the size of the child," Dr. Charlton said.

A child should use an adult seat belt only when he or she can sit against the back of the rear seat with the knees bent comfortably at the edge of the seat. The lap belt should rest low and snug across the hips and not across the stomach and the shoulder belt should be centred on the shoulder and chest.

Booster seats help younger children who have outgrown child seats to sit high enough to enable them to sit all the way back against the seat, without having to slouch, and with their knees bent over the edge of the seat. This allows:

• the lap belt to fit more snugly over the bony pelvis, rather than the soft abdomen, and
• the shoulder belt to remain better positioned over the shoulder and chest, rather than riding up into the chin and face.

According to MUARC, around 900 children aged ten years and under are killed or seriously injured as occupants of passenger cars across Australia each year.