A helmet aims to decrease the risk of serious head and brain injury by reducing the impact of a force or collision to the head. A helmet works in three ways:
1. It prevents direct contact between the skull and the impacting object by acting as a mechanical barrier between the head and the object;
2. It spreads the forces of the impact over a greater surface area so that they are not concentrated on a particular area of the skull; and
3. It absorbs the impact energy and reduces the magnitude of the forces transmitted to the skull and brain.
good quality helmet is made with expanded polystyrene (EPS) lining that absorbs
the impact to the head in a crash, decreasing the severity of serious head or
brain injury. The lining is covered with a hard outer shell that cushions the
head and reduces the extent of trauma. For maximum protection, the helmet must
fit snug on the head and have strong straps to ensure the helmet will stay on
in the event of a crash.
Low quality helmets are often made with cheap materials that break easily and do not protect the brain. These helmets typically contain poor quality foam that is soft and it will not withstand an impact. A low quality helmet may also use straps that break easily and not fit well, aspects that can contribute to a higher severity of injuries in a crash.