Spatial and Social Equity in Access to Emergency Service Facilities—An Opportunity–Outcome Perspective

Equity in access to emergency service facilities (ESFs) is essential for ensuring residents’ safety and well-being. Previous studies on equity in access to ESFs have mainly focused on individual facilities or single dimensions, failing to capture the overall fairness of the emergency service system as an integrated entity. This study introduces an integrated opportunity–outcome evaluation framework to examine spatial and social equity in access to ESFs at the community scale, with particular attention to disparities across facility types, spatial levels, and socioeconomic groups. A machine learning-based approach combining XGBoost and SHAP is employed to identify key spatial and non-spatial factors influencing ESF accessibility. The results indicate that: (1) In terms of opportunity equity, spatial accessibility to ESFs varies significantly, with lower accessibility in southwestern Yongdeng County and northern Gaolan County. (2) Regarding outcome equity, a significant spatial mismatch exists between emergency resource distribution and population demand, resulting in polarization between oversupply and insufficiency, with the FSs supply–demand imbalance being the most pronounced. Low-income groups, rural residents, and the elderly face greater difficulty accessing ESFs compared to the general population. Among all variables, average elevation is found to be a decisive factor affecting accessibility. Based on these findings, the study proposes a zoning-based planning strategy for ESFs in Lanzhou. This strategy offers practical guidance for improving future regional ESF planning, enhancing urban emergency response capacity and resilience.