Measuring spatio-temporal disparity of location-based accessibility to emergency medical services.

The importance and sensitivity of the time dimension in the emergency medical service (EMS) field have been widely recognized in recent years. However, the EMS spatio-temporal disparity remains partially uncovered in traditional accessibility measurements due to EMS's context-sensitive characteristics and demand specificity. In this study, we obtained dynamic traffic conditions and realistic EMS demand from online map services and historical emergency calls-out data, and then developed three location-based spatio-temporal EMS accessibility measurements. The empirical results demonstrate that the three different spatio-temporal EMS accessibility have a complex relationship, and are beneficial for measuring the EMS spatio-temporal disparity in different scenarios with distinct competitive effects. Ultimately, we emphasized four original EMS accessibility patterns, which helped us uncover significantly well-served or underserved areas. This study contributes to optimize the layout of EMS resources by understanding the regularity of EMS spatio-temporal disparity.