New study claims bicycle helmets reduce odds of serious injury by nearly 70 percent. But what does that mean?

dutch cycling
CC BY 2.0 FaceMePLS

No more Dutch style cycling for you; The Guardian reports on a new study by Australian statisticians Jake Olivier and Prudence Creighton that claims helmets reduce the risks of serious head injury by nearly 70 percent.

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 found.

No doubt the helmet nannies will pick up on this study and quote it often; the abstract of the study concludes:

Bicycle helmet use was associated with reduced odds of head injury, serious head injury, facial injury and fatal head injury. The reduction was greater for serious or fatal head injury. Neck injury was rare and not associated with helmet use. These results support the use of strategies to increase the uptake of bicycle helmets as part of a comprehensive cycling safety plan.

That makes sense. Helmets do prevent injuries and save lives. That's why we have to wear them on construction sites which are dangerous places where things fall on your head. But so far as I can tell, the study doesn't look at the rate of accidents, which surely matters. This is what risk means, and according to Kay Teschke of the School of Population and Public Health, University of British Columbia, who tweeted me a note:

The authors of the study seem to be very careful not to use that word, because they did not study risk. Their review is about the odds of a head injury given [a cyclist has an] injury. The studies take place at hospitals and they count the cyclists with head injuries wearing or not wearing a helmet and compare them to those with other injuries wearing or not wearing a helmet. The evidence on this issue is not contentious, helmets reduce the odds of a head injury among those who are injured when cycling (and would do the same for walking, car driving, etc. as many people have pointed out).

Another Australian study compared the rate of head injuries in different modes and found the following risk of head injury per million hours travelled:

  • Cyclist - 0.41
  • Pedestrian - 0.80
  • Motor vehicle occupant - 0.46
  • Motorcyclist - 7.66

That study concluded:

Despite the risk of dying from head injury per hour being similar for unhelmeted cyclists and motor vehicle occupants, cyclists alone have been required to wear head protection. Helmets for motor vehicle occupants ...have the potential to save 17 times as many people from death by head injury as a helmet law for cyclists without the adverse effects of discouraging a healthy and pollution free mode of transport.

And I suspect that whatever you do, whether it is walking, driving, or sitting in a park under a tree, you are probably 70 percent less likely to have a head injury if you are wearing a helmet.

Since we know that head injuries are more common and happen at a higher rate while walking or driving than cycling, why are they not encouraged or legally bound to wear helmets? Why do they get to sit helmetless in their cars and criticize cyclists? After all, the data are pretty clear that cycling is not much more dangerous for your head than driving and half as dangerous as walking.

The blunt answer is, this is not about cyclists’ safety. It’s about power, about fear, and and about shifting responsibility instead of providing safe infrastructure or making cars slow down. It might even be about scaring cyclists off the road because everybody knows that streets are made for cars and trucks and parking and bikes are just getting in the way.

woamn on bikeFaceMePLS on Flickr/CC BY 2.0

In the Netherlands, almost nobody wears a helmet, and yet the rate of crashes and head injuries is lower than anywhere else in the world. As one Guardian commenter noted:

In Holland very few people wear helmets because we have a tremendous cycling infrastructure, and because for us cycling is as natural as walking. So we don't generally wear any specialist cycling kit, nor do we, as a rule, cycle on fancy racing bikes. Dutch people will hop on anything with two wheels, however scruffy it may be, in their regular clothes. And not wearing a helmet adds to this tremendous sense of freedom and ease. You hop on and off in a split-second, as you please, where and when you you want.

bike laneLloyd Alter/ Shaw Street state of the art bike lane/CC BY 2.0

I wear a helmet, but I wish I didn't feel I have to

And in Toronto where I live, I often get forced into treacherous streetcar tracks by cars and construction. The bike lanes, where they exist, are often door zone deathtraps or like this one I ride on regularly, totally a joke or blocked by Fedex trucks. No wonder I wear a helmet. In fact, you can find a pretty direct correlation between rate of injury and rate of helmet use because the more dangerous the cycling environment, the more we armour up. As Kay Teschke notes,

...the real question is the risk of head injury (or other injury) if you go cycling. Here the evidence is either no effect of helmets, or greater risk where helmet use is more common. In between-country comparisons of injury or fatality risk, there is much lower risk in Holland and Denmark than US, Australia, Canada. Also lower risk on bike share bikes than personal bikes despite lower helmet use in the former. This is the important question.

life in the fedex laneLloyd Alter/ Life in the Fedex lane/CC BY 2.0

Other studies have shown that where there are mandatory helmet laws, fewer people ride bikes. They infer that they are then getting less exercise and are less healthy and perhaps more people die earlier from other causes. In fact, one study calculated that "the benefits of cycling, even without a helmet, have been estimated to outweigh the hazards by a factor of 20 to 1."

If we want more people to ride bikes, because it is healthy and it gets them out of cars, we have to make it easy and have to make it feel safe. That means bike lanes and infrastructure and a vision zero approach, not going on about helmets. What we should be aiming for is a world where everyone feels as safe as those cycling in Amsterdam, not everyone wearing helmets.

I repeat here the great infographic from Bekka Wright, AKA Bikeyface

bikeyface prevention© Bikeyface

Tags: Bike-Friendly World | Bikes | Biking | Cities

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