Green commutes: Assessing the associations between green space exposure along GPS-track commuting routes and adults’ self-perceived stress

Habitual commutes through green space may be associated with health promotion, including stress alleviation. However, few studies have assessed green space exposure during commuting with stress levels, and none have tracked commuters' actual routes. To assess 1) the association between commuting through green space and people's self-perceived stress, 2) whether the association is moderated by the transport mode, and 3) whether the association depends on differing green space operationalizations and buffer sizes. This cross-sectional study used questionnaires and global positioning system data from Dutch adults aged 18-65 (N=275). The Perceived Stress Scale was used to measure people's stress levels. Green space was measured by calculating the green space percentage from land use data (GREENLU), and by using normalized difference vegetation index (NDVI) obtained from Sentinel-2 (NDVISE) and Landsat-8 (NDVILS) satellite imagery. Buffers of 50, 100, and 250 m along commuting routes were applied to assess subjects' environmental exposures. Associations were estimated using ordinary least squares regression models. Covariate-adjusted regressions showed that GREENLU was significantly but positively associated with stress levels, regardless of buffer size. By contrast, the NDVI measures consistently showed null associations. We observed a positive association between GREENLU and stress levels among active commuters within the 250 m buffer in stratified analyses, however, associations were null for passive commuters across all green space measures and buffer sizes. Our findings suggest a counterintuitive positive association between increased exposure to green space during daily commutes and people's stress levels. These associations possibly may depend on the selected green space metric, the buffer sizes, and the commuting mode considered. The behavioral aspects of how people experience green environments, including commuting, may contribute to their impact on health.