LeBlanc JC, Beattie TL, Culligan C. Canadian Medical Association Journal 2002;166(5): p592-5
In the two years preceding and three years following the enacting of mandatory helmet legislation in July 1997, observers recorded helmet use, sex and age group of cyclists in Halifax, Nova Scotia. Sampling took place during peak hour on sunny days along arterial, residential and recreational roads.. Data on bicycle-related injuries treated during the same period at the Emergency Department of the IWK Health Centre, Halifax was used to monitor injury trends.
The rate of helmet use rose dramatically after legislation was enacted, from 36% in 1995 and 38% in 1996, to 75% in 1997, 86% in 1998 and 84% in 1999. The proportion of injured cyclists with head injuries in 1998/99 was half that in 1995/96 (7/443 [1.6%] v. 15/416 [3.6%]).
Another article in the same issue of the CMA Journal (Chipman, 2002) gives further information and suggests different conclusions. The number of cyclists observed per day dropped from nearly 90 in 1995/96 to 34 in 1997 and 52 in 1998/99. Also, the proportion of the child cyclists observed decreased, from 8.1% before the legislation to 6.1% in the year it was introduced to 3.7% 2 years afterwards.
This is consistent with people responding to the legislation by cycling less themselves and discouraging their children from cycling. This is also consistent with patterns observed previously in New South Wales and Victoria, Australia, before and after helmet legislation was enacted. Although in Nova Scotia the numbers of helmeted cyclists went up following legislation, this increase was much less than the numbers of people who stopped cycling. The author believes that if legislation has discouraged people, particularly children, from cycling, this is a negative effect that requires both acknowledgement and response.
Subsequent correspondence published in CMAJ (Wardlaw, 2002b) notes that although the absolute number of head injuries had fallen by half post-legislation, so had the number of cyclists, and the total number of injuries (mostly non-head) increased. Likewise, the claim of a doubling in the rate of helmet use omits the more telling point that the absolute number of cyclists using helmets did not materially change.
The author notes that "The Nova Scotia helmet law experience strengthens the arguments against helmet laws. No reduction has occurred in the risk of head injury per cyclist, relative to this study's loose definition of head injury. However, a big increase has occurred in the risk of non-head injury per cyclist. Furthermore, there has been no material increase in the number of helmeted cyclists. Rather, cycling on a substantial scale has been deterred. The deterrence of the safest mode of urban transport will not contribute to overall road safety or public health."
Chipman ML, 2002. Hats off (or not?) to helmet legislation. Canadian Medical Association Journal 2002 Mar 5;166(5):602.
Wardlaw MW, 2002. Butting heads over bicycle helmets. Canadian Medical Association Journal August 20, 2002; 167 (4).