The impact of the healthy city pilot program on social engagement among middle- and older-aged adults in China

As population aging continues in China, promoting social engagement among middle- and older-aged adults has become a key component of advancing the active aging strategy. Existing research focused primarily on individual-level determinants, with insufficient attention to the shaping role of the macro-level policy environment. As a comprehensive policy initiative, the Healthy City Pilot (HCP) program may support social engagement among middle- and older-aged adults by continuously improving the natural environment, social environment, and health services. However, empirical evidence on its effectiveness and underlying mechanisms remain limited. Accordingly, this study examines whether and through which pathways the HCP program promotes social engagement among middle- and older-aged adults. Using four waves of panel data from the China Health and Retirement Longitudinal Study (CHARLS) conducted in 2011, 2013, 2015, and 2018, this study included middle- and older-aged adults aged 45 years and above, yielding 52,407 person-wave observations. The core empirical analysis employed a Difference-in-Differences (DID) model to estimate the causal effect of the HCP program on social engagement. And exploratory mechanism-consistency check was conducted to examine the roles of physical and mental health. The results showed that the HCP program significantly improved social engagement among middle- and older-aged adults ( \(β\) =0.582, P < 0.01), and this finding remained robust across a series of robustness checks. The policy effect was more pronounced among males, those with lower educational attainment, relatively younger individuals, and those with a spouse. Mechanism-consistency check further indicated that physical and mental health played a limited mediating role. This study provides micro-level causal evidence for the positive social benefits of the HCP program for the first time. To better advance active aging through the HCP program, future policy should strengthen public communication and program quality, expand pilot coverage, balance inclusive environmental improvement with targeted services, broaden health services to better meet actual needs, and give equal attention to physical and mental health.