Using GPS-enabled cell phones to examine adolescent travel patterns and exposure to alcohol outlets

Background: As adolescents gain freedom to explore new environments unsupervised, exposure to high alcohol outlet density areas may increase risks for alcohol, tobacco, and other drug (ATOD) use and delinquency. Few studies have examined influences of the proportion of time spent near outlets on adolescent risk behavior, using real-time positional data.

Methods: In this pilot study, adolescents (N=18) aged 16-17 (50% female) carried GPS-enabled smartphones for one week during which their locations were tracked. Dynamic contexts, all the places adolescents spend time, were created by connecting GPS points sequentially and adding spatial buffers (30m, 100m, 200m) around routes. Alcohol outlet data were joined to routes. Outcomes included self-reported ATOD use and delinquency.

Results: Adolescents spent 28.5% of their time away from home, and 25.4% of their time away from their residential census tract. Proportion of time away from home and from the residential tract did not vary by gender, ATOD use or delinquency. There were variations in the time of day and day of the week adolescents were exposed to alcohol outlets. Exposure was greatest during after school hours (3-9pm); on average 37.4% of after school hours were within 200m of an alcohol outlet. Drinkers, smokers, marijuana users, and adolescents engaged in delinquency were exposed to outlets for greater proportions of time than adolescents not engaged in these behaviors.

Conclusions: These findings based on GPS technology may inform adolescent prevention research by providing more specific information about where teens spend time and their times of greatest exposure to contextual risk.