The contribution of light levels to ethnic differences in child pedestrian injury risk: a case-only analysis

Background: Many studies in countries across the world have identified minority ethnic children at higher risk of pedestrian injury compared to their majority counterparts. Understanding why minority ethnicity increases risk has proved challenging. One hypothesis which has not, to date, been explicitly tested in the published literature is the 'conspicuity hypothesis': namely that ethnic differences in pedestrian risk may reflect differences in the relative 'visibility' of some groups in traffic environments. This study investigates whether the 'conspicuity hypothesis' can help explain ethnic inequalities in child pedestrian injury risk in London. Methods: Using a time series of police injury records in London from 2000-2009 we assess the impact of sunlight levels on child pedestrian injury controlling for diurnal patterns of injuries and weather conditions. We then explore the distribution of casualties by ethnic group using a case-only analysis to assess whether light intensity has a differential effect on injury risk by ethnic group. Results: All children were at increased injury risk during civil twilight (the hour after sunrise and the hour before sunset) compared with during the day. We found no association between astronomical twilight (the hour after sunset and the hour before sunrise) and night time and injury. We found no evidence for the conspicuity hypothesis. A similar proportion of 'Black and 'White' child pedestrian injuries occur during darkness, and our models found that light levels had a similar effect on injury risk to children from all ethnic groups. Conclusion: There was no evidence that non-White minority ethnic children in London are at higher risk of injury because they are less conspicuous at night time. (C) 2014 Elsevier Ltd. All rights reserved.