height.
A child whose sitting height is 63 cm or more should be seated on a booster until it becomes possible to use and safely adjust the seat belt alone. When that time comes, one must make sure that:
When children are seated in the vehicle, their back is flat against the back of the seat and their knees are bent over the edge. The child must be able to maintain this position during the whole trip. When the seat belt is fastened, it must cross over the middle of the shoulder (the clavicle) and over the hips. It must not rest near the neck or on the stomach.
Alteration of Safety Devices for Occupants
It is prohibited to alter or remove a vehicle’s original seat belts or render them unusable.
It is also prohibited to alter a child safety seat, which must be installed in accordance with the manufacturer’s instructions.
Airbags p. 17
"Autopsy" of an Accident
When a moving vehicle comes to a sudden stop, the people in it are projected forward at the speed at which it was going and tend to maintain that speed. The same is true of any loose objects or baggage placed or hung inside the vehicle. The reason is that the vehicle, people, objects and baggage were all travelling at the same speed.
A collision can be described as follows:
First, the vehicle hits the object in its way. The energy released by the sudden stop is transferred to the vehicle, which absorbs it in part. Next, the vehicle’s occupants continue to move forward toward the point of impact. Various things in the vehicle can slow them down: seat belts, if worn; airbags, if the vehicle is equipped with them; and internal features like the steering wheel, dashboard and windshield. If nothing slows them down, the occupant’s bodies are likely to be ejected from the vehicle.
Lastly, the occupant’s internal organs (brain, liver, lungs, etc.), which are relatively unrestrained, remain in motion until they run into bony structures like the skull or rib cage.