Fires were also a huge part in mandating full face helmets. Every injury that I have heard of from a full face helmet also included the use of a factory air bag that made impact with the helmet. Just for sharing knowledge, I would like to see the study that shows closed face helmets are more dangerous than open face.
Nobody said they are more dangerous. The point is, there is no free ride. The study merely cited several incidences of C1 fractures caused by a force on the chin bar that separated the spinal cord from the brain stem. This always results in death.
I don't have much time today to cut and paste research, but here is a single incident that demonstrates the dangers of a full face helmet.
Cooter, R.D., David, D.J., McLean, A.J., & Simpson, D.A. (1988). Helmet-induced skull base fracture in motorcyclist. The Lancet, 8577, 84-85.
Abstract
Purpose & Study Population. Case study of a 19-year-old male motorcyclist who fell from his motorcycle at an intersection, slid along the road, and struck the front of his helmet on the edge of a curb, resulting in unconsciousness, blood flow from the ear canals, and death, despite the apparent absence of facial damage.
Data & Methods. Radiology (CT scan) of both head and helmet, plus necropsy of victim, focusing on head.
Results & Conclusion. Observations suggested that the face bar of a full-face helmet may transmit an impacting force to the skull base via the chin strap and the mandibular rami and condyles, bypassing the energy-absorbing facial bones. If this mechanism is confirmed, the structural properties of these face bars will need to be reassessed.
Strengths
Both the victim and the helmet were examined thoroughly using CT scans and other methods.
The authors make appropriately modest recommendations. They suggest only a reassessment of the structural properties of the face bar; they do not question the overall value of helmets in general or of full-face helmets in particular.
Weaknesses
The medical conclusion is somewhat speculative - as the authors implicitly acknowledge when they suggest the need for confirmation of their proposed injury mechanism. We, as economists, are not qualified to evaluate the medical theory, but several researchers who have looked into the hypothesis of injury from full-face helmets have discredited the theory. (See, for example: Thom, D.R. & Hurt, H.H. (1993). Basilar Skull Fractures in Fatal Motorcycle Crashes. 37th Annual Proceedings, AAAM, 61-76. An evaluation of Cooter et al. appears on page 65.)
Even if the proposed injury mechanism is correct for this one case, it is difficult to draw more general inferences from a single case, especially in light of the unusual way the injury occurred. Perhaps the crash was unsurvivable, and in the absence of the face bar, the victim would have may died when his chin or throat hit the curb. Moreover, even if the face bars of full-face helmets were responsible for occasional deaths, it is possible that they might save even more lives. The present article gives no way to evaluate the aggregate impact of the face bar.
Goldstein, J.P. (1986). The effect of motorcycle helmet use on the probability of fatality and the severity of head and neck injuries: A latent variable framework. Evaluation Review 10(3), 355-375.
Excerpt from another study:
The transfer of impact energy through helmet retention systems, causing brain stem tearing and basal skull fractures, has been noted as the mechanism of injury in a number of studies. (A blow to the chin bar of a full face helmet transfers the impact energy to the retention system. The force is then transferred through the mandibular condials to the base of the skull, its weakest point.) Frontal impact causing hyperextension of the neck is also likely in causing cervical dislocation and placing traction on the brain stem, resulting in tearing of the pontomedullary junction. The pons is relatively thick compared to the medulla. It is at the thin point of the junction that the tearing occurs.
D.A. Simpson, et al noted that of thirteen helmeted motorcyclists, nine had principal impacts to the chin bar or face causing tears of the pontomedullary junction. Four who suffered either vertex or lateral impacts had corresponding brain stem tears. The mechanism is postulated to be similar to that of frontal impacts.
The transfer of impact energy through helmet retention systems, causing brain stem tearing and basal skull fractures, has been noted as the mechanism of injury in a number of studies. (A blow to the chin bar of a full face helmet transfers the impact energy to the retention system. The force is then transferred through the mandibular condials to the base of the skull, its weakest point.) Frontal impact causing hyperextension of the neck is also likely in causing cervical dislocation and placing traction on the brain stem, resulting in tearing of the pontomedullary junction. The pons is relatively thick compared to the medulla. It is at the thin point of the junction that the tearing occurs.
D.A. Simpson, et al noted that of thirteen helmeted motorcyclists, nine had principal impacts to the chin bar or face causing tears of the pontomedullary junction. Four who suffered either vertex or lateral impacts had corresponding brain stem tears. The mechanism is postulated to be similar to that of frontal impacts.
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