Personal Noise and Nonoptimum Temperature Exposures and Myocardial Ischemia: Independent Effects and Two-Way Effect Modifications

It remains unknown whether noise and nonoptimum temperature exposures are linked to myocardial ischemia, either separately or jointly. We conducted a multicenter panel study with 24 h real-time personal measurements among generally healthy middle-aged and elderly individuals to investigate potential effects of short-term personal exposures to noise and temperature on ST-segment depression event (STDE) and whether the effects of noise are modified by temperature and vice versa. Generalized linear mixed-effect model and stratified analyses were used. A total of 117 eligible participants completed 256 person-visits. We found increased risks of STDE associated with personal noise exposure and U-shaped exposure–effect relationships between personal temperature exposure and risks of STDE, both occurring over minutes to hours. The nonoptimum temperatures, including low and high temperatures, significantly enhanced the adverse effects of noise on STDE. Significant effect modifications on temperature-related STDE risk by noise were found in both the low and high temperature ranges. Exploratory analyses suggested that decreases in heart rate variability variables, reflecting autonomic imbalance, may explain exposure-related STDE occurrence. Our study identified the independent effects and two-way effect modifications of personal noise and temperature exposures on STDE risk, providing novel insights into the pathways linking these environmental factors to adverse cardiovascular outcomes.