Several objectively measured urban-environment features are associated with objectively measured physical activity across diverse cities.

This page isolates one claim from the wider argument of The Human OS Manual.

The classification describes the evidence supporting this claim, not the Human OS framework as a whole.

Sallis and colleagues studied 6,822 adults in 14 cities across ten countries. Residential density, intersection density, public-transport density, and number of parks were positively associated with accelerometer-measured moderate-to-vigorous physical activity in single-variable models.

The study is cross-sectional and does not establish that changing one urban feature causes a specific increase in activity, that every built-environment feature matters equally, or that the findings directly measure aging outcomes.

The public claim is narrower than the chapter’s long-horizon statement about place as an aging variable.

Supported by appropriate human studies, major reviews, trials, cohort research, or converging evidence. The strength of the category does not remove population, dose, timing, or context limitations.

Sources are listed according to the role they play in this claim. One source may provide direct support, another may explain a mechanism, establish a limitation, or prevent an interpretation from becoming broader than the evidence allows.

The printed book preserves the claim inside the argument that gives it meaning. These references connect the current digital record to the first-edition evidence trail.

This claim connects to the following parts of the Human OS architecture. The module labels locate the claim inside the framework; they do not imply that the research source validates the architecture itself.