Satellite-Based and Street-View Green Space and Adiposity in US Children

Abstract

Importance: Green space may be associated with obesity outcomes in children by promoting physical activity and reducing stress. However, previous studies have mostly used a single measure of green space and body mass index (BMI) as the sole indicator of adiposity.

Objective: To examine associations of the satellite-based normalized difference vegetation index (NDVI) and street-view imagery-based green space metrics with comprehensive adiposity measures in children.

Design, setting, and participants: The Project Viva cohort study observed participants from mid-childhood (mean [SD] age, 8.0 [0.8] years) and early adolescence (mean [SD] age, 13.3 [1.0] years) through late adolescence (mean [SD] age, 17.8 [0.7] years) between January 1, 2007, and December 31, 2021. This analysis included children with data on green space and adiposity measures. Data were analyzed from January 1 to June 30, 2024.

Exposures: Green space metrics (ie, percentage of trees, grass, and other green space) using street-view imagery and deep learning algorithms along with the NDVI were linked with participants' home addresses during mid-childhood and early adolescence.

Main outcomes and measures: Body mass index (calculated as weight in kilograms divided by height in meters squared) and waist circumference z scores were calculated from anthropometric measurements during early and late adolescence. The total fat mass index (FMI; calculated as fat mass in kilograms divided by height in meters squared) and trunk FMI were obtained using dual-energy x-ray absorptiometry. Separate linear regression models adjusted for a child's age, sex, individual and neighborhood socioeconomic status, and population density estimated prospective associations of the NDVI and street-view green space (in mid-childhood or early adolescence) with 4 adiposity measures (in early or late adolescence).

Results: The sample included 843 children (mean [SD] age at mid-childhood, 7.9 [0.8] years; 423 girls [50.2%]) at baseline. After adjustment for confounders, a higher NDVI (per 1-SD increase) within 270 m in early adolescence was associated with lower z scores for BMI (-0.16 [95% CI, -0.27 to -0.04]) and waist circumference (-0.13 [95% CI, -0.23 to -0.03]), as well as a lower total FMI (-0.62 [95% CI, -1.02 to -0.23]) and trunk FMI (-0.33 [95% CI, -0.55 to -0.12]) in late adolescence. Higher percentages of street-view other green space (flowers, plants, and fields), but not street-view trees and grass, within 500 m in early adolescence were associated with lower BMI z scores (-0.09 [95% CI, -0.18 to -0.01) in late adolescence. The NDVI and street-view green space exposure at mid-childhood were not associated with adiposity measures in early adolescence.

Conclusions and relevance: This cohort study of US children suggests that higher levels of satellite-based NDVI greenness and percentages of street-level green space components (flowers, plants, and fields) were associated with lower adiposity. The findings support the exploration of increasing residential green space levels and adding specific green space components as an urban planning and public health intervention strategy to combat the prevalence of childhood obesity in the US.

Figure 1.. Estimated β Coefficients of 2 Prospective Associations of Street-View and Satellite-Based Green Space Measures (Per SD Increment) With 4 Adiposity Measures Among Children From Project Viva

A, Mid-childhood green space exposure and early adolescence adiposity outcome. B, Early adolescence green space exposure and late adolescence adiposity outcome. Percentages of trees, grass, and other green space are mutually adjusted. Additional covariates included age, sex, race and ethnicity, prepregnancy body mass index (BMI), maternal educational level, paternal educational level, marital status, household income, neighborhood median income, and population density. The normalized difference vegetation index (NDVI) was highly correlated with the street-view trees metric (r = 0.84); therefore, they were fitted as separate models.

Figure 2.. Effect Modification by Child’s Sex of the Association of Street-View and Satellite-Based Green Space Measures (Per SD Increment) at the Early Adolescence Visit With 4 Adiposity Measures in Late Adolescence in Children From Project Viva

A, Body mass index (BMI) z score. B, Waist circumference z score. C, Total fat mass index. D, Trunk fat mass index. Percentages of trees, grass, and other green space are mutually adjusted. Additional covariates included age, sex, race and ethnicity, prepregnancy BMI, maternal educational level, paternal educational level, marital status, household income, neighborhood median income, and population density. The normalized difference vegetation index (NDVI) was highly correlated with the street-view trees metric (r = 0.84); therefore, they were fitted as separate models.