Ambient Temperature and Injury-Related Hospital Admissions in China: A 10-Year Time-Series Analysis Using Distributed Lag Non-linear Model

Background Ambient temperature is an important environmental factor affecting population health. While its effects on mortality and chronic diseases have been widely studied, less is known about its role in injury risk. In rapidly urbanizing settings, temperature may influence injury occurrence through changes in behavior, mobility, and exposure patterns. This study aimed to examine the association between ambient temperature and injury-related hospital admissions in Shanghai, China. Methods A time-series analysis was conducted using daily injury-related hospital admissions in Shanghai from 2016 to 2025. Meteorological data, including daily mean temperature and relative humidity, were obtained from local monitoring systems. The association between temperature and injury-related hospital admissions was assessed using a distributed lag non-linear model to account for non-linear and delayed effects. Subgroup analyses were performed by age, sex, and injury mechanism. Results A total of 2,000,847 injury-related hospital admissions were included. The relationship between ambient temperature and injury-related hospital admissions showed a non-linear pattern, with the highest risk observed at moderate temperatures. At higher temperatures, the overall risk decreased, although traffic-related injuries continued to increase. In contrast, fall-related injuries showed a declining trend at high temperatures. Heat-related effects were short-term, while cold-related effects were weaker and more gradual. Subgroup analyses indicated higher risks among younger adults under high temperatures and slightly increased risks among older adults under cold conditions. Conclusions Ambient temperature is associated with injury risk in a non-linear and mechanism-specific manner. The overall pattern reflects the combined effects of different injury types with distinct responses to temperature. These findings suggest that injury prevention strategies should consider not only extreme temperatures but also moderate conditions, as well as population differences and behavioral factors. Integrating temperature-related risks into urban planning and public health strategies may help reduce the injury burden in the context of climate change.