Operationalization of Activity Space for Measurement of Environmental Exposures

Authors: Kelly Jones*, National Soclo-Environmental Synthesis Center, Shannon N Zenk, University of Illinois at Chicago, Stephen A Matthews, The Pennsylvania State University
Topics: Geography and Urban Health
Keywords: activity space, urban, health
Session Type: Paper
Day: 4/4/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Truman, Marriott, Mezzanine Level
Presentation File: No File Uploaded


Understanding the relationship between individuals’ exposures and health behaviors or outcomes can suggest novel interventions to improve population health. Thus, understanding individual activity spaces, or the locations in which people conduct their daily activities, is an area where collaboration between geographers and health researchers is important. With the advent of highly accurate, wearable global positioning systems (GPS) trackers, identifying precise, time-stamped geographic coordinates has become routine. Yet converting resultant big datasets to useful activity space measures remains elusive. In this study, we collected GPS waypoints at 1 minute intervals from 86 individuals over 14 days as they performed their normal daily activities in the metropolitan Chicago region. We then used geographic information systems software to operationalize activity spaces five different ways for each participant: convex hull, standard deviational ellipse, buffered route, time-weighted density surface, and point-based exposure. We measured exposure to a variety of health-related environmental resources (e.g., parks, food stores) for each activity space. Correlations were calculated between environmental exposures derived from different operationalizations of activity space to identify the impact of activity space operationalization on exposure measurement. We conclude that activity space operationalization exerts significant influence on the measurement of exposure. Finally, we discuss unique features of each activity space operationalization and suggest types of research questions and environmental exposures for which each may be appropriate. We suggest that a conceptual match between activity space operationalization and the context of the specific research study is imperative to truly understand the effect of exposure on health.

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