Using objective and subjective measures of neighborhood greenness and accessible destinations for understanding walking trips and BMI in Seattle, Washington.

PURPOSE: Examine the influence of destinations within walking distance of a residence and vegetation on walking trips and body mass index (BMI).
DESIGN: Cross-sectional analysis of data from residences with varying accessibility and greenness.
SETTING: Seattle, Washington.
SUBJECTS: Stratified random sample of residents, stratified by accessibility and greenness. RESPONSE RATE: 17.5 %, 529 respondents. MEASURES: Accessibility and greenness were measured objectively by Geographic Information Systems (GIS) Network Analysis and normalized difference vegetation index (NDVI), respectively. Self-reported destinations, natural features, walking trips, BMI, and importance of destinations were measured through a postal survey.
RESULTS: Objective accessibility were related to walking trips per month (r(2) = .110, p < .0001), as was subjective greenness (r(2) = .051, p < .0001), although objective measures of actual greenness were not. In areas with high accessibility, BMI was lower in areas that had high NDVI, or more greenness (r(2) = .129428, model p < .0001; t-test of interaction p = .0257). Low NDVI areas were associated with overestimation of the number of destinations within walking distance (F1, 499 = 11.009, p = .001).
CONCLUSIONS: Objective and subjective measurements of accessibility and greenness led to an understanding of variation among walking trips and BMI in different neighborhoods.