title: The association of ambient air pollution and physical inactivity in the United States.
abstract: BACKGROUND
  Physical inactivity, ambient air pollution and obesity are modifiable risk factors for non-communicable diseases, with the first accounting for 10% of premature deaths worldwide. Although community level interventions may target each simultaneously, research on the relationship between these risk factors is lacking.
  
  
  OBJECTIVE
  After comparing spatial interpolation methods to determine the best predictor for particulate matter (PM2.5; PM10) and ozone (O3) exposures throughout the U.S., we evaluated the cross-sectional association of ambient air pollution with leisure-time physical inactivity among adults.
  
  
  METHODS
  In this cross-sectional study, we assessed leisure-time physical inactivity using individual self-reported survey data from the Centers for Disease Control and Prevention's 2011 Behavioral Risk Factor Surveillance System. These data were combined with county-level U.S. Environmental Protection Agency air pollution exposure estimates using two interpolation methods (Inverse Distance Weighting and Empirical Bayesian Kriging). Finally, we evaluated whether those exposed to higher levels of air pollution were less active by performing logistic regression, adjusting for demographic and behavioral risk factors, and after stratifying by body weight category.
  
  
  RESULTS
  With Empirical Bayesian Kriging air pollution values, we estimated a statistically significant 16-35% relative increase in the odds of leisure-time physical inactivity per exposure class increase of PM2.5 in the fully adjusted model across the normal weight respondents (p-value<0.0001). Evidence suggested a relationship between the increasing dose of PM2.5 exposure and the increasing odds of physical inactivity.
  
  
  CONCLUSIONS
  In a nationally representative, cross-sectional sample, increased community level air pollution is associated with reduced leisure-time physical activity particularly among the normal weight. Although our design precludes a causal inference, these results provide additional evidence that air pollution should be investigated as an environmental determinant of inactivity.
authors.affiliation: Department of Preventive Medicine and Biometrics, F. Edward Hebert School of Medicine, Uniformed Services University, Bethesda, Maryland, United States of America.
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Roberts
authors.affiliation: Department of Preventive Medicine and Biometrics, F. Edward Hebert School of Medicine, Uniformed Services University, Bethesda, Maryland, United States of America; Epidemiology Consult Service, United States Air Force School of Aerospace Medicine, Wright-Patterson Air Force Base, Ohio, United States of America.
authors.forename: Jameson D
authors.initials: JD
authors.lastname: Voss
authors.affiliation: Department of Preventive Medicine and Biometrics, F. Edward Hebert School of Medicine, Uniformed Services University, Bethesda, Maryland, United States of America.
authors.forename: Brandon
authors.initials: B
authors.lastname: Knight
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000397:Air Pollution / Q000009:adverse effects*; D001499:Bayes Theorem; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010126:Ozone / Q000009:adverse effects; D052638:Particulate Matter / Q000633:toxicity*; D015995:Prevalence; D012307:Risk Factors; D057185:Sedentary Behavior; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D052638:Particulate Matter; D010126:Ozone