Background Incorrect bicycle helmet use increases head injury risk.

Objective To evaluate the patterns of incorrect helmet use based on unobtrusive field observations.

Methods Two observational surveys conducted in Alberta in 2000 and 2006 captured information on cyclist characteristics, including correct helmet use. Prevalence of correct helmet use was compared across multiple factors: age, gender, riding companionship, and environmental factors such as riding location, neighbourhood median family income, and region. Poisson regression analysis was used to relate predictor variables to the prevalence of incorrect helmet use, adjusting for clustering by site of observation.

Results Among helmeted cyclists (n=5862), 15.3% were wearing their helmet incorrectly or were using a non-bicycle helmet. Children (53%) and adults (51%) tended to wear their helmet too far back, while adolescents tended not have their straps fastened (48%). Incorrect helmet use declined approximately 50% over the study period for children and adolescents, but 76% (95% CI 68% to 82%) in adults. Children were 1.8 times more likely to use their helmets incorrectly in 2000 compared with adults, but this effect increased to 3.9 (95% CI 2.9 to 5.4) in 2006. Adolescents were more likely to use their helmets incorrectly in 2006 compared with adults (prevalence ratio 2.76; 95% CI 1.9 to 4.02). Children and adolescents cycling alone, compared with adults cycling alone, cycling at non-school sites and cycling in Edmonton, was associated with incorrect helmet use.

Conclusions Important factors not previously identified were associated with incorrect bicycle helmet use. This information can be used to target interventions to increase correct use.