This study in Austin-Travis County, Texas, examines the relationship between heat index patterns and heat-related EMS incidents during summer. Analyzing hourly weather and EMS call data, the research uses a distributed lag non-linear model (DLNM) to assess immediate health effects of extreme heat events. Results reveal that higher heat intensity has immediate short-term lagged effects on all causes of heat-related EMS incidents, including cardiovascular, respiratory, neurological, and non-severe cases, with varying relative risks over time. Additionally, hourly excess heat (HEH) shows a short-term cumulative lagged effect within 5 hours for all-cause, cardiovascular, and non-severe symptoms, while statistically significant relative risks are not found for respiratory and neurological cases in the short term. These findings offer policymakers insights for resource allocation, extreme heat warning standards, and optimizing local EMS services, providing data-driven evidence for effective ambulance deployment strategies.
