Individual mobility patterns and real-time geo-spatial exposure to point-of-sale tobacco marketing

Health-related behaviors occur as part of a broad socio-ecological context that unfolds dynamically over time. Yet systematic quantification of the way individuals come into contact with health-related features in their local environment remains a difficult challenge. Doing so requires a multi-tiered approach that integrates both individual geo-location data and comprehensive community-level information about health-related features in the local built environment. This report describes the implementation of a system for quantification of real-time exposure to point-of-sale tobacco marketing via mobile phone geo-location tracking. Individual mobility patterns from a longitudinal cohort of DC residents (N=486) were overlaid on an existing community-level point-of-sale surveillance geodatabase (N=1, 080 stores). Participants were DC residents who carried a geo-location tracking device over the first 8-weeks of a smoking cessation attempt. Tracking data were then used to produce a mobility "signature," physically linking each person to their surrounding point-of-sale marketing environment in real-time. Results demonstrate the dynamic nature of an individuals' experience of the point-of-sale environment. We identify substantial between-person differences in tobacco product pricing exposure, and find that these correspond to clusters of individuals whose price exposures vary systematically over time of day. These data suggest that perceptions of the point-of-sale environment as relatively static fail to account for the mobility and preferences of individuals as they actively engage with their neighborhoods over time.