The urban traffic environment and the risk of child pedestrian injury: a case-crossover approach.

We conducted a case-crossover study to quantify the effects of traffic volume and speed on the risk of child pedestrian injury on the school-home journey. We identified 46 children injured as pedestrians on the school-home journey. For each case, we compared the traffic volume and speed on the road where the child was struck with the volumes and speeds on the other roads the child would usually cross. We found strong associations between pedestrian injury risk and high traffic volume [relative risk = 6.3; 95% confidence interval (CI) = 2.1-18.8] and high speed (relative risk = 3.6; 95% CI = 1.5-8.4). These results provide suggestions as to future applications of the case-crossover design.