Synergistic Effects and Transmission Pathway Analysis of Key Atmospheric Control Zones and Forest City Construction on Residents’ Health

The establishment of Key Atmospheric Control Zones and Forest City Construction represents a crucial ecological institutional innovation for advancing the “Healthy China” initiative and sustainable urban development. Prior research has largely focused on the intrinsic link between individual policies and residents’ health, yet generally overlooked the health-improving effects generated by policy coordination. Leveraging observations spanning 2011–2020 from the China Health and Retirement Longitudinal Study, this paper employs an extended diff-in-diff approach to assess the impact and channels of the “Dual Pilot” initiative on residents’ health. Results indicate that: (1) The “Dual Pilot” initiative produces a substantially enhanced synergistic influence on residents’ health compared with the “single pilot” approach, proving resilient after parallel trend tests, placebo tests, and robustness checks. (2) Improvements operate mainly via three mediating channels: expanding green space access, fostering green technology innovation, and boosting government environmental expenditure. (3) Heterogeneity analysis reveals significant effects for women, individuals aged ≥60, and those with higher education, while effects on men, individuals aged 45–59, and those with lower education are insignificant; at the societal level, the policy exerts markedly positive impacts on urban residents and contributes to sustainable urban health improvement, but fails to reach significance for rural residents and regions with underdeveloped medical systems.