Bicycle helmets are tested with vertical drops from a maximum height of about 3m onto flat surfaces (BS/EN 1078:1997). In such testing, helmets definitely help. However, the scientific evidence on helmets & population wide injury rates is far from clear that helmets actually are beneficial.
While amongst cyclists who suffer injury, helmets of themselves do reduce head injuries significantly, they also increase neck and facial injuries, so that there appears to be negligible benefit overall (Accident Analysis & Prevention: … meta-analysis of bicycle helmet efficacy). Study of bicycle injury rates in Australia around the time of introduction of mandatory helmet laws suggests that, though there is a noticeable dip in injury rates around the introduction of the law itself (not necessarily attributable to the helmet itself in my opinion) that injury rates then started increasing again, to the point rates were nearly the same at the end of the study period as before the helmet law, and trending to surpass it! (My Blog: study-shows-australian-cyclist-helmet-law-leads-to-increasing-head-injury-rates). Helmet use also appears to induce risk-compensation behaviour in motor vehicle drivers – they make closer passes (Accident Analysis & Prevention: Drivers overtaking bicyclists…). No doubt the cyclists themselves also are subject to risk compensation. Thus, by wearing a helmet there may be an increased risk of getting into an accident.
There may be further population wide psychological effects caused by a culture of “Must be wearing a helmet to be safe!”. It is sending the message that cycling needs safety equipment, and hence must be dangerous, which surely will put off many – certainly where mandatory helmet use laws are introduced rates of cycling then significantly decrease. The reverse is of course true: the overall health benefits of cycling greatly outweigh the quite tiny risks – risks which are not greatly changed by helmet wearing, the studies appear to say. In other words, by advocating helmet use, one may be harming the rates of cycling by sending the wrong message on safety, and hence harming public health overall.
Further, as cyclist safety on the roads correlates strongly with rates of cycling – more cyclists leads to more awareness & safer roads, and similarly fewer cyclists means less safe roads – this means a culture of helmet use may well lead to increased injury rates amongst cyclists (in addition to the general adverse public health effects of fewer people cycling). This would be very hard to categorically prove or disprove in causal terms, however the Australian experience certainly suggests a correlation, as I think would a comparison of the UK and Netherlands.
Finally, in the Netherlands, one of the safest places for cycling in the world, cyclists almost universally do not wear helmets, including very young cyclists. Thus, we can be quite certain that helmet usage is not a pre-requisite for safe cycling. Indeed, it is in places like the UK and USA, with some of the worst cycling safety in the developed world, where the focus on safety equipment for the cyclist seems to be greatest.
In short, the focus needs to be on those things around the cyclist (e.g. default legal liability to influence motorists’ behaviour, safer road infrastructure, etc) – not what is on cyclists. Focusing on cyclist safety equipment to me seems futile at best, and perhaps even detrimental to the cause of mass, safe cycling, if that’s a cause you believe worthwhile.
NB: Helmet use should always be a personal choice. The issue is complex, the trade-offs may differ greatly in different scenarios – helmets may be very beneficial in some settings, e.g. some kinds of racing. The choice should be your own. However, general advocacy of cycling helmets seems inappropriate and probably harmful, to me.
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Tim Beadle said
The BBC’s insistence that anyone cycling on TV (certainly on kids’ TV) be wearing a helmet is a massive example of this “dangerisation” of cycling. The worst example I’ve seen is the CBeebies show “Same Smile” where the presenter, riding a cargo trike at about 4mph, is seen wearing a helmet. Utterly bonkers, and detrimental to the cause of getting more people cycling.
Paul Jakma said
Madness indeed. Presumably if they were seated, their head was lower than if they were upright. So, if they were going at walking pace on the trike, then their head was at *decreased* risk of injury relative to walking. In other words, the BBC ought to also make this presenter wear a helmet while walking! 😉
Richard Burton said
The BBC is engaged in a campaign to promote cycle helmets, and has been doing so for over twenty years. They have a Charter which is very specific about impartiality and bias, but every programme that I am aware of has been blatantly, undeniably partial and biased. Despite many complaints and being provided with overwhelming evidence, the BBC deny any bias.
The latest was The One Show broadcast in the spring, which gave three times as much time to helmet proponents as sceptics and interviewed James Cracknell, who claimed that his helmet saved his life, without pointing out that he is sponsored by the helmet manufacturer. According to the BBC this is impartial and isn’t bias.
Kim said
I think you will find that the worst cycling safety in the developed world is actually Australia and New Zealand, oh and they have compulsory cycle helmets for everyone.
seamus gardiner said
probably why they need to wear helmets then….
Paul Jakma said
Another interesting study here: http://bit.ly/uogrwR – which appears to confirm the Sheffield study in that gender & appearance of the cyclist affect the behaviour of motorists in how close they pass.
Paul Jakma said
The paper concerned is also discussed here: http://theconversation.edu.au/putting-a-lid-on-the-debate-mandatory-helmet-laws-reduce-head-injuries-1979 with interesting debate in the comments section, including from the authors.
Paul Jakma said
A prior paper to the one discussed in this blog, which was found to have flaws and withdrawn, to which the paper discussed above was partly in response to, is discussed here: http://blogs.crikey.com.au/croakey/2010/12/09/did-we-make-mistakes-in-our-study-yes-but-our-argument-stands-says-researcher-who-queries-the-merit-of-cycle-helmet-laws/ – where its authors argue the flaws found do not detract from its point.
Paul Jakma said
Another study showing helmet laws do reduce cycling head injuries in children. However, it is accompanied by increase in head injuries in children from other causes, suggesting that the cycling decrease is due to drop in cycling rates rather than the effect of the helmets on crashes:
http://www.nber.org/papers/w18773
Paul Jakma said
Helmet wearers cycle more slowly if made to cycle without: http://www.sciencedirect.com/science/article/pii/S0001457512001169
Paul Jakma said
Study of New Zealand helmet laws suggests a negative impact on mortality, due to the significant decrease in cycling post-law:
Paul Jakma said
The paper “The Health Impact of Mandatory Bicycle Helmet Laws”
tries to mathematically model aspects of the net health benefits of cycling relative to the negative impacts on cycling participation of mandatory helmets laws. It finds that generally such laws lead to a significant *negative* effect on overall health:
Paul Jakma said
Canadian study published in the BMJ, “Helmet legislation and admissions to hospital for cycling related head injuries in Canadian provinces and territories: interrupted time series analysis”, finds helmet law legislation has had a minimal effect on hospital admissions for cyclist head injuries:
Paul Jakma said
BMJ editorial piece, by Ben Goldacre and David Spiegelhalter, on the risks of cycling and the net effect of helmet promotion on public health, “Bicycle helmets and the law” has an overview of the issues, and good references.
Paul Jakma said
The Vine magazine in Australia, with a good overview of the public health issues of helmet laws and the scientific evidence, inc links.
Paul Jakma said
An interesting overview of the data and research on the effect of mandatory helmet law in Alberta, Canada:
Paul Jakma said
Very good quantitative article on the effect of helmet law introduction in New Zealand on injury and participation rates. In a nutshell, participation dropped dramatically amongst all age groups while injury rates increases.
Paul Jakma said
Blog commenting on the impact of the New Zealand helmet law, which appears to led to reduced cycling (as in AU), and increased risk to the remaining cyclists. Links to (partisan) websites with further data.
Paul Jakma said
Study of swedish children’s helmet law shows no effect in head injury rates for females; a decrease in head injuries for males, but accompanied by an increase in other injuries.
The study notes the admission data categorises injuries into primary and secondary injuries, and their study is counting the primary injury, which means the head injuries could still be there amongst the males. It could be other injuries have gotten worse, with head injuries the same, so that the other injuries tend to get classed as primary. Or it could be head injuries, if still present, tended to be less worse, and other injuries the same, leading to the other injuries to be classed as primary. Or some mix.
http://www.sciencedirect.com/science/article/pii/S0022437514000723
Paul Jakma said
Using hospital admissions data as the basis for helmet efficacy studies overestimates their efficacy, potentially greatly.