Exposure to consecutive extreme ozone-heatwave events and neurological disorders: a retrospective cohort study in Nanjing, China.

Abstract

Objectives: In the context of global warming and escalating urbanization, occurrences of extreme ozone (EO) and heatwave (HW) events are increasingly frequent. However, studies on the impact of consecutive extreme ozone and heatwave (EO-HW) events on hospitalizations for neurological disorders (ND) and related economic burdens remains limited. Our study aimed to explore the impacts of these events on ND hospitalizations, length of stay, and related costs, with a specific focus on quantifying the impacts of consecutive extreme events of varying durations.

Methods: Time-series analysis was performed to investigate the relationships between consecutive O₃ and HW events of varying durations and the number of hospitalizations, length of stay, and hospitalization costs for ND, employing a quasi-Poisson distributed‑lag non‑linear model (DLNM). In addition, we further identified potential high-risk groups by age and gender stratification.

Results: Exposure to EO-HW events were associated with an increased risk of hospitalization for ND, with this risk persisting from lag 1 day (1.097, 95% CI: 1.005,1.198) to lag 4 days (1.071, 95% CI: 1.004,1.139). Significant associations were particularly evident in male (highest RR value 1.092, 95% CI: 1.016,1.173) and aged < 65 years (highest RR value 1.124, 95% CI: 1.008,1.254). Furthermore, exposure to EO-HW events were found to result in longer length of stay and higher hospitalization costs compared to exposure to HW events alone.

Conclusions: Consecutive EO-HW events significantly increase the risk of hospitalization and the economic burden of ND. Local authorities should consider incorporating early warning information and public health interventions for consecutive extreme weather into existing early warning systems. Neglecting to do so will likely result in higher associated illness rates and economic burdens.