Should we cyclists bother to wear helmets?

Fascinating letter in yesterday’s Financial Times:

Sir, There has been debate about helmets and cyclists’ safety (‘Some healthy advice, Boris: please put a lid on it’, July 1, and Letters, July 3 and 4). As author of a number of papers on the topic, I may be able to inform the discussion.

Driving helmet use is zero. Walking helmet use is zero. None of this is controversial. The cycle helmet debate must stem from a belief that cycling is much more dangerous than walking or driving. Serious analysis of risk has been lacking. In the late 1980s, the Transport and Road Research Laboratory produced a report called Risk in Cycling. It was never published. I obtained a copy from a private library. Disturbed by the ill-informed basis of debate, I expanded on the TRRL work and published Assessing the Actual Risks Faced by Cyclists in 2002.

The main conclusions were:

* On-road cycling is a low-risk form of travel in all the countries assessed, including the UK. Cyclists face risks similar to drivers or pedestrians. For instance, even an active British cyclist faces lower lifetime risks than the average French or Belgian driver.

* If there is more cycling, it gets safer; if there is a drop in cycling, the risk per cyclist increases.

These findings have been repeated by a later study for the European Cycling Federation. Wearing a helmet for daily cycling is only “important” if such travel is actually dangerous. Since it is not actually dangerous, it cannot be important to wear a helmet. Boris Johnson ought to have made this clear in his article in a national newspaper a few weeks ago.

Be wary of gruesome anecdotes about smashed helmets. Helmet laws have been in force in Australia and New Zealand for more than 15 years. Although initial studies claimed modest improvements from these laws, the issue was largely settled in 2006 in a paper in the British Medical Journal. This showed that no discernible reduction in serious head injuries could be seen in the hospital admission data from those countries with sharply rising helmet use, although there was some reduction in scalp lacerations. Note that three published studies have observed an excess of deaths with rising helmet use (in the US, UK and Australia). Personally, I cannot understand why the issue is still debated at all.

The health benefits of cycling vastly exceed the risks of being killed in a crash, being comparable to giving up cigarette smoking. It is the sedentary lifestyle of car-dependency that is truly dangerous. Cycling to work dodges the jams and a gives you a workout all in one shot. Countries with cycle helmet laws, or strong helmet policies, have the highest levels of obesity. These countries also have the poorest safety records, due to the low level of cycle use.

In London, half of road deaths are pedestrians, just 6 per cent are cyclists. I cannot understand anyone involved in casualty treatment who insists cyclists should wear helmets, when they themselves do not wear a walking helmet.

Malcolm Wardlaw,

Very interesting. The argument is not watertight, though, for a couple of reasons. One is the Peltzman effect: it could be that behelmeted cyclists take advantage of an increase in safety by taking more risks, such as cycling faster and running more red lights. If that was true (I am not aware of any research on the question) then helmets would not seem to make cyclists safer from the view of the statistician, but they would be giving cyclists the (privately) beneficial ability to get to their destinations more quickly.

Nor is it true that helmet use is justified only if cycling is more dangerous than walking or driving. That is not the question: the question is the marginal benefit of the helmet. If pedestrians don’t wear airbags, that is not because walking is safer than driving, but because airbags offer no benefits to pedestrians.

Interesting to note that half of London road deaths are of pedestrians and six per cent are of cyclists. Proves nothing by itself, but ten times as many “journey stages” in London were by foot as by cycle. (source: p6) That suggests, broadly, that the risks of a cycle journey are about the same as the risks of a pedestrian journey. Who knew?

I’ll keep wearing a helmet. I am

a) Risk averse and more importantly

b) Signalling to my wife that I pay attention to her opinion.

Update: I should have remembered to point out that the letter was one of many responses to my colleague Stefan Stern’s column here.

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Tim, also known as the Undercover Economist, writes about the economics of everyday life.