Update: The Irish Government subsequently decided not to pursue an Irish helmet law at the present time.
The Irish National Safety Council (NSC) has called for the mandatory wearing of cycle helmets, especially by children. The NSC claims that international research has shown countries with helmet laws have significantly increased helmet usage and consequently reduced head injuries among cyclists.
Are these claims correct? The NSC cites five reports to support its contention that a helmet law would improve safety:
This report has been widely criticised for its lack of balance, for considering only one type of evidence on helmet effectiveness and the omission of much crucially relevant information. For example, the section cited by the NSC on the effect of a helmet law in Victoria, Australia, seriously misrepresents the data on cycling activity. It fails to mention that the decrease in cycling with the law was 4 times greater than the increase in helmet wearing, or that the relative risk of head injury actually increased following legislation for those who continued to cycle.
This is a case-control study. Like many others, it found that, for cyclists given hospital treatment, helmet wearers tend to have fewer head injuries than non-wearers. Is this because helmets offer some benefit, or that those who choose to wear helmets are more cautious, have different riding styles and get into less serious accidents? Without additional information (which is difficult to obtain) either explanation could be true. Other studies have found that cyclists choosing to wear helmets also have less serious non-head injuries. If helmets are really effective, we should see large reductions in head injury when helmet laws are passed. This has not proved to be the case.
The report shows there was a substantial drop in head injuries with the law. There was, however, little discussion of the substantial drop in non-head injuries that also took place. The falls in both head and non-head injuries imply that the effect of the law was mainly to discourage cycling, rather than prevent cyclists' head injuries when crashes occurred. Moreover, a comparison of head injuries to cyclists and pedestrians shows that the risk of head injury to cyclists actually increased compared to what it would have been without the law.
Another article in the same issue of the CMA Journal drew attention to the fact that LeBlanc's own data showed that cycle use had declined post-law by at least as much as head injuries. Also the number of new helmet wearers was much less than the number of people who had stopped cycling as a result of the law. Letters critical of the article's conclusions were also published subsequently by CMAJ.
A detailed criticism of this paper was published in a subsequent issue of Accident Analysis and Prevention. NSC makes no reference to this and appears not to have taken it into account.
The National Safety Council appears not to have considered the contradictory evidence about cycle helmet effectiveness. Moreover it makes no reference at all to the extensive evidence that helmet laws result in many fewer people cycling, or to the consequences of this for the environment, or the health of people in Ireland at a time when the main threats to health and longevity are illnesses such as obesity and heart disease which result in large part from inactivity. There is no comparison of the net benefit to Ireland of fewer people cycling with helmets against more people cycling without.