Spatial equity-oriented accessibility assessment and optimal allocation of older adult care facilities in Beijing’s central urban area

Introduction: Population aging is a pressing global public health challenge. In aging-concentrated urban central areas, accelerated population aging has worsened the mismatch between supply and demand, irrational spatial layout, and inadequate accessibility of older adult care resources. Methods: To improve public service equity, this study took Beijing's central urban area as the research object. Using data from the 2018 Beijing Special Census on Targeted Assistance for older adults and the 2020 Full-Coverage Census of older adult care Facilities, facility accessibility was evaluated using an improved Ga2SFCA method. The number of required facilities was determined via K-means clustering combined with the elbow rule, and optimal locations was verified using particle swarm optimization and remote sensing images. Results: The results showed that: (1) Accessibility of older adult care facilities was spatially imbalanced, with some areas lacking coverage or only having single-type facilities. (2) Community service stations were the most accessible, especially in Dongcheng and Xicheng districts; older adult care centers had the lowest accessibility; while older adult care institutions performed better in peripheral zones.(3) We proposed an optimal allocation plan with 16 new facilities in underserved residential areas with high concentrations of older adults. Discussion: This integrated framework improves the precision of accessibility evaluation and site optimization. The findings offer empirical support for equitable older adult care policy-making in Beijing, helping enhance service equity and sustainable development.