Over on VOX, Joseph Stromberg rounds up the studies about bike helmets and concludes that if you want to get more people to ride bikes, then you shouldn't force them to wear helmets. I looked at most of these studies in 2009, so here is an update of our post and a look at Stromberg's.
Before I start, I should point out that nobody is saying you shouldn't wear a helmet; I do most of the time, I feel safer. The question is, again, whether there should be laws that force people to wear them and whether there should be all these pro-helmet campaigns. So following Stromberg's lead,
Why are only cyclists targeted for helmets?
As Mikael Colville-Andersen and Hart Noecker of Rebel Metropolis have pointed out, one is much more likely to have a head injury in a car than on a bike. The absolute number of head injuries is staggering in comparison; Stromberg shows that even looking at the number of injuries per hour of travel, which compensates for the fact that there are a lot more drivers than cyclists, the rate of head injuries is not significantly different between walking, cycling or driving.
In fact, if anyone needs a helmet, it is the pedestrian, who has even higher rates of head injuries than cyclists.
Do helmets actually work?
According to an oft-repeated study in the New England Journal of Medicine , they do, leading to an 88% reduction in the risk of brain injury. That study has been seriously challenged both on a statistical basis and a logical one.
Even if helmets are effective, it does not follow that all cyclists should wear them. Racing car drivers wear helmets, but not people driving to work. The difference is the level of risk. For the same reason, racing cyclists and mountain bikers often choose to wear helmets, but riding down a quiet road to the corner shop is a generally safe activity. Driving and cycling have similar risks per hour of serious head injury.
Stromberg references other studies that show a far lower rate, and also finds evidence that helmet laws didn't significantly reduce the overall rate of head injuries.
Are Helmeted Cyclists "car magnets?"
Stromberg quotes Ian Walker's experiment, which found that drivers were less careful around helmeted cyclists. In fact, Walker found that the best thing you can do is put on a wig: drivers give women more room.
test cyclists were given 8.5cm (3.3 inches) more clearance by cars if they were not wearing helmets. When the researchers donned female wigs they got more clearance, 14cm (5.5 inches) more than apparent males in helmets. They did not report on what a skirt and helmet combination would do. The author was hit by a bus and a truck during the experiment, and was wearing a helmet both times.
Does wearing a helmet encourage more dangerous riding practices?
Stromberg writes "Many people also suggest that wearing a helmet makes cyclists themselves less cautious in their riding, increasing the chance of an accident. This is unproven, and it's a difficult topic to research. " In fact, there is evidence that the opposite is true, helmeted cyclists are more careful riders.
Dorothy Robertson wrote in her study "Do enforced bicycle helmet laws improve public health?":
Cyclists who chose to wear helmets commit fewer traffic violations, have higher socioeconomic status, are more likely to wear high visibility clothing and use lights at night.
Do Helmet Laws reduce the use of bicycles dramatically?
Stromberg claims yes, and has data to prove it, looking at what happened in Australia as helmet laws were rolled out. And based on Australian research by Dorothy Robertson, it's true. She wrote:
The effect of unpopular helmet laws on cycling activity is readily seen. In Melbourne, surveys were conducted pre-law in May 1990 and post-law in May 1991, at the same 64 sites and same observation times. Counts of child and adult cyclists declined by 42% and 29% respectively. In total, 297 more helmeted cyclists were counted than pre-law, compared with 1100 fewer cyclists. It's as if the law didn't so much encourage helmet wearing as discourage cycling!
In fact, Helmet laws might kill more people than they save.
Helmet laws like those in effect in Australia levy a substantial cost on healthcare systems because savings from fewer head injuries pale in comparison to the costs incurred by decreases in cycling, a mathematical model concludes.... de Jong created a model that can be adjusted by putting in various values for drops in cycling rates due to helmet laws, the cost of an accident due to not wearing a helmet, and the overall health benefit of cycling.
It turns out that so many people are turned off cycling by helmets that the the lives saved through the exercise and health benefits of cycling among people is greater than the number of lives saved through helmet use.
Finally, the biggest influence on safety is the number of cyclists on the road, so you don't want to do anything that scares them away.
Stromberg writes: "It's been proven over and over again that the most important predictor of a city or region's level of safety for bikers is the number of bikers on the road." He shows the graph from Peter Jacobsen's study Safety in numbers: more walkers and bicyclists, safer walking and bicycling Jacobsen's key findings:
- Where, or when, more people walk or bicycle, the less likely any of them are to be injured by motorists. There is safety in numbers.
- Motorist behavior evidently largely controls the likelihood of collisions with people walking and bicycling.
- Policies that increase walking and bicycling appear to be an effective route to improving the safety of people walking and bicycling.
Stromberg shows this extraordinary graph that shows how cities with lots of cyclists (and very few helmet wearers) have a far lower death rate than the USA or UK. The death rate is pretty much inversely proportional to the number of people cycling.
One can also infer from this graph that the death rate is inversely proportional to the quality of the infrastructure. Helmet use appears to have nothing to do with it.
My key takeaways from all this data when I first looked at it in 2009:
We need better biking infrastructure to separate us from stupid drivers. That is the lesson from the Netherlands, that we need more cyclists and better bike paths more than we need helmets.
Who is responsible? Helmet laws and campaigns could be considered a shifting of responsibility from the governments that refuse to provide decent cycling infrastructure to the heads of cyclists. Whenever a cyclist is crushed under the wheels of a big truck the papers say "XXX wasn't wearing a helmet" when the real cause of the accident was bad road and truck design or lack of side-guards. As I noted in Is the lack of a bike helmet the "underlying cause" of cycling fatalities? about a cyclist who got the right hook from a cement mixer:
My rowing buddy Hubert was killed this way. Jenna Morrison was killed this way. They were both wearing helmets. The underlying causes are lousy infrastructure and the lack of side-guards on trucks, not whether there was a piece of foam on their heads. This has nothing to do with helmets.
Helmets work. it is silly to say that they don't; if you are going to hit your head into something they will help protect it. Bulletproof vests work too, but even though 30 people a day are killed by guns in America, there is a surprising lack of pressure for people to wear one.
If you don't live in the Netherlands or Copenhagen or somewhere with lots of cyclists and a decent infrastructure, and feel like wearing a helmet, do it. I do. But don't treat helmets as the solution to the problem of bad infrastructure, and don't treat cyclists differently than everyone else.