Wearing a helmet reduces the odds of serious head injury by 69 per cent, and fatal head injury by 65 per cent, according to an analysis from the University of New South Wales in Australia.
Statisticians Jake Olivier and Prudence Creighton reviewed data from 64,000 cyclist injuries, across 40 studies and found helmet use was associated with reduced odds of head and serious or fatal head injury, as well as facial injury. Helmets had no effect on neck injuries.
Helmets are a sticky issue, with some researchers branding mandatory cycle helmet laws in Australia a “public health disaster”, reducing cycling rates (and the associated health benefits) without improving injury rates on a population-wide basis.
Findings from the “largest ever systematic review and meta-analysis of bicycle injury and helmet use” were most striking for serious and fatal head injuries.
The study’s authors conclude: “Helmet use is associated with odds reductions of 51% for head injury, 69% for serious head injury, 33% for face injury and 65% for fatal head injury. Injuries to the neck were rare and not associated with helmet use.”
The study points out cycling injuries are rare - there are 0.29 crashes per 1000km cycled in Australia, and in just eight per cent of those cases medical treatment is sought. According to Australian hospital and police data 34 per cent of hospital admitted cyclists have a head injury, 15 per cent of those serious.
Though researchers recognised the difficulties of generalising this data analysis to a population level, they suggest “results could be used as one source of evidence for the promotion of bicycle helmets for mitigating head, serious head, face and fatal head injuries".
"Irrespective of past research, the results of this review do not support arguments against helmet legislation from an injury prevention perspective."
However, they add, "bicycle helmets are not a panacea for cycling injury, as they do not eliminate head or face injury and they do not offer protection to other body regions. Any comprehensive cycling safety strategy should consider the promotion or legislation of bicycle helmets only in concert with other injury prevention strategies."
Cycle helmets are only designed to withstand collisions at speeds of 5.42-5.52m/s, or a little over 12mph.
Researchers have advised caution in applying helmet safety data to population level, due to the effect of "risk compensation" and the possible effects of helmet laws in reducing cycling rates. The former is a hypothesis where helmet wearers exhibit greater risk-taking behaviour, while some motorists drive closer to helmeted cyclists, though Olivier and Creighton say there is "very little published research on the topic and no systematic review".
Earlier this year Cycle-helmets.com analysed government data and found the number of bicycle trips in the Australian state of Victoria declined by 44.7 per cent from 1985/6 and 2012/13, between which mandatory helmet laws were introduced, while a 2015 Canadian study found no link between helmet laws and head injury rates.
Chris Gillham is a research journalist who investigated the Australian helmet law when it was introduced in 1991, and who maintains the website www.cycle-helmets.com.
In a submission to the Australian senate last year, which heard helmet laws do more harm than good, he said: "Data published over the past 25 years has consistently shown a substantial and permanent decline in the proportion of Australians cycling, with consequent damage to public health.
"The data show tens and probably hundreds of thousands of Australians are discouraged from regular or occasional recreational exercise and instead mostly use their cars for transport, increasing traffic congestion and the likelihood of road trauma."
Gilham pointed to hospital records suggesting helmet laws resulted in a 10-20% decline in the proportion of cyclist head injury but an approximate 30% increase in the total number of cyclist admissions. Some argue this is due to the reduced “safety in numbers” effect as fewer people cycle.
Luke Turner, a Senior Infrastructure Advisor, wrote in the Institute of Public Affairs journal: "By any measure, health problems associated with a lack of exercise are a far greater problem than cycling head injuries in Australia. According to the Heart Foundation, lack of physical activity causes 16,000 premature deaths each year, swamping the 40 or so cycling fatalities."
Sydney cyclists are now being hit with enormous fines for misdemeanours including £163 penalties for not wearing helmets as part of a cycling-focused crackdown by police.