Acute solar and atmospheric shifts preceding emergency department presentations for intentional drug overdose

Intentional drug overdose (IDO) is a major cause of emergency department (ED) presentations. While psychiatric and psychosocial factors are established contributors, many events occur without identifiable triggers. Emerging evidence suggests that rapid environmental changes may act as acute behavioral stressors influencing self-harm risk. This study investigates whether short-term increases in solar insolation and related atmospheric conditions are associated with IDO presentations, using a 15-day harmonic mean (HM15) model to detect individualized environmental deviations.

This retrospective cohort study included adults presenting with IDO to a tertiary ED in Muğla, Türkiye between July 1, 2019 and July 1, 2024. Environmental data-including solar insolation, temperature at 2 m (T2M), ultraviolet (UV) radiation, and humidity-were obtained from the NASA POWER database. For each case, index-day values were compared to the individual's preceding HM15 baseline.

Among 515 IDO patients, solar insolation, T2M, and UV radiation on the index day were significantly higher than HM15 baselines (all P < 0.001). These deviations were most pronounced in spring and early summer, aligning with established peaks in suicide risk. In spring, a 15.6 % surge in solar insolation was observed, alongside significant increases in T2M and UV exposure. Similar abrupt shifts were noted in summer, while autumn and winter demonstrated mixed environmental patterns.

Acute rises in solar insolation, temperature, and UV radiation are temporally associated with increased IDO risk. The HM15 model may support real-time, meteorologically informed, AI-enhanced risk stratification in ED-based suicide prevention and merits evaluation for integration into clinical decision support systems.