Patterns of association between environmental quality and physical inactivity vary across the rural-urban continuum

Physical inactivity has been associated with numerous adverse health outcomes including obesity, heart disease, and depression, and is considered a major contributor to all-cause mortality worldwide. Many studies have shown associations between specific environmental features (lack of sidewalks, safe surroundings, clean air) and physical inactivity. Yet, exposures affecting inactivity do not occur in isolation. Understanding the role of the overall ambient environment in population inactivity levels is essential. A novel county-level Environmental Quality Index (EQI) was developed by the Environmental Protection Agency (EPA) for all US counties from 2000-2005 representing 5 environmental domains: air, water, land, built, and sociodemographic. We linked the EQI to 2006 Behavioral Risk Factor Surveillance System county-level prevalence of age-adjusted physical inactivity in US counties (N=3,141). We used random intercept multi-level linear regression, clustering by state, to estimate fixed effects of EQI quintiles on physical inactivity prevalence. Analyses were stratified by 4 modified United States Department of Agriculture rural-urban continuum codes (RUCC) ranging from metropolitan urbanized (RUCC1) to rural (RUCC4). Results are reported as prevalence difference (PD) (95% confidence interval) comparing highest quintile/worst quality to lowest/best. For the overall EQI, negative quality environments were associated with reduced physical inactivity (RUCC1: -5.07(-5.65, -4.49); RUCC2: -3.36(-4.70, -2.01), RUCC3: -3.35(-4.00, -2.71); RUCC4: -2.55(-3.18, -1.92). However, in domain-specific EQI analyses, patterns of association (strength and direction) varied by RUCC: RUCC1, sociodemographic domain PD=4.56 (4.04, 5.08) and built PD=-4.07(-4.66, -3.48); RUCC2, air PD=1.96 (0.78, 3.13) and sociodemographic PD=-5.03, (-6.18, -3.89); RUCC3, air PD=1.24 (0.64, 1.84) and built PD=-1.23(-1.74, -0.71); RUCC4, sociodemographic PD=-3.00(-3.64, -2.37) and air PD=1.86 (0.98, 2.75). Physical inactivity was influenced by multiple domains of environmental quality depending on the extent of urbanization. These results provide useful information for environmental research and programs aimed at reducing county-level physical inactivity. This abstract does not necessarily reflect EPA policy.