Background: Although underground metro systems enhance urban transportation, their potential mental health impacts remain a public concern. Objective: This study aims to investigate the association between residential floor height, subway-induced noise and vibration, and depressive symptoms, and to evaluate the accuracy of conventional floor-to-floor prediction models. Methods: Indoor noise and vibration were measured on all floors of a multistory building adjacent to the Tehran Metro. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9). Results: Noise and vibration levels decreased with increasing floor height, demonstrating a clear exposure gradient. Higher exposure was significantly associated with greater depressive symptom severity. PHQ-9 scores declined with floor level in the adjusted model ( β = −0.33 points per floor, P = 0.011). The Federal Transit Administration (FTA) predictions closely matched measured vibration but overestimated noise, with greater deviation at higher floors ( P = 0.002). Notably, PHQ-9 scores exceeded the clinical cutoff (≥10) on all floors, including those below FTA allowable exposure limits. Conclusions: The floor-to-floor reductions averaged approximately 2 dB for vibration and 2.6 dB for noise. Current predictive frameworks and uniform allowable exposure limits may underestimate the long-term psychological impacts across building floors. Refinement of exposure criteria, together with frequency-based noise evaluation, may better protect residents’ mental health.
Sadeghi et al. (Sun,) studied this question.