The bicycle helmet and its promotion has been a controversial subject amongst cyclists, safety experts and the medical profession, for many years.
Common sense, case-control studies by respected scientists, strong promotion by manufacturers, and possibly wishful thinking, are the basis for the majority view that bicycle helmets are beneficial at the individual level and therefore at society level.
Case-control studies and Population-based studies
The case-control studies, which have received strong scientific opposition, generally conclude helmets are beneficial on the individual level. One central problem is the number of factors involved and the problem of adjusting for the self-selection of helmet usage. Self reported helmet usage might also be heavily skewed.
Population based studies have concluded that no added safety is discernible as a response in head injury numbers, when helmet usage has increased dramatically. Some population level studies have concluded otherwise, but they have generally not taken into account the reduction in cycling, generally accompanying large scale uptake of helmets that followed enforced compulsion or strong promotion.
Population based studies in general can also be criticized on the grounds that there are many variables that can influence changes in cyclists safety. One way to analyze the general changes in traffic safety is to compare cyclists and pedestrians, and to compare trends in serious head injuries to other injuries. The way in which trends in head injuries in cyclists and pedestrians follow each other virtually in lock-step through a period when helmet usage grew dramatically, and other striking features of the datasets, merit special attention.
Individual benefit and society benefit
Bicycle advocates have been saying since the 1990's, and possibly earlier, that even though bicycle helmets might provide a limited safety benefit to a subset of users (specifically children falling off at low speeds onto nearly flat surfaces) at the individual level, they will probably be detrimental at society level (and can increase injuries to adults due to the increased radius of the head providing a lever to amplify rotational injuries), through various mechanisms:
- The image being presented that cycling is especially dangerous, scares people from cycling
- Making it the cyclists' responsibility to pay for attempts to protect against the danger poised largely by cars and lorries. Cyclists pay by the wallet, by considerable inconvenience
- Potential reductions in safety through risk compensation (supporting scientific evidence exists)
- Potential reductions in safety through "safety in numbers" in reverse (supporting scientific evidence exists)
All these represent unfair reductions in the viability of cycling as a competitive means of transport. And that is especially unfortunate as cycling is at any rate adding to health much more than traffic accidents with cyclist involvements deduct from health. Additionally reduced cycling means losing the beneficial effects of cycling on pollution levels (local air pollution, global air pollution, noise pollution, water pollution), oil dependence, obesity, congestion, the strengthening of local communities, etc.
Lost life-years and safety in numbers
Besides this daily cycling is so healthy that if helmet compulsion or strong promotion reduces cycling the net health effect in lost life-years will be large and negative, even if helmets could magically prevent all road accidents involving cyclist. (Andersen et al 2000) Additionally reduced cycling has been shown to reduce the safety of the remaining cyclists, while increasing cyclist numbers increase their safety. The effect is known as "Safety in numbers"
- Wikipedia:en:Bicycle_helmet General history, as well as information on the standards and the controversy.
- Bicycle Helmet Research Foundation (sceptical)
- helmets.org rebuttal of anti compulsion arguments (pro-helmet)
- All-Cause Mortality Associated With Physical Activity During Leisure Time, Work, Sports, and Cycling to Work, Lars Bo Andersen, PhD, DMSc; Peter Schnohr, MD; Marianne Schroll, PhD, DMSc; Hans Ole Hein, MD, Arch Intern Med. 2000;160:1621-1628.
- No clear evidence from countries that have enforced the wearing of helmets, Dorothy Robinson, BMJ 2006; 332: 722-725