LAUSR

We assessed the effect of wearing a junior-high-school helmet when the frontal or lateral part of a helmet impacted the upper part and lower part of the A-pillar of a vehicle at 35 km/h (212 J). The head injury criterions (HICs) of the headform impactor without a helmet were respectively 4530 and 4937. In the case of the headform impactor wearing a junior-high-school helmet, the helmet reduced the HIC by 17.5 % and 9.9 % for impacts of the frontal part of the helmet and by 15.0 % and 4.0 % for impacts of the lateral part of the helmet. We also assessed the effect of wearing a junior-high-school helmet when the frontal part of the helmet impacted a road surface from a height of 1.5 m (66 J). The HIC of the headform impactor without a helmet was 6525. The HIC was reduced by 82.7 % when wearing a junior-high-school helmet. Both experiments show that, under a relatively low impact energy condition such as a road surface impact, wearing a junior-highschool helmet greatly reduces the head injury level. Meanwhile, under a relatively high-impact-energy condition such as impact against an A-pillar, wearing a junior-high-school helmet is ineffective in reducing the head injury level.