Association\nof Ozone and Temperature with Ischemic\nHeart Disease Mortality Risk: Mediation and Interaction Analyses

Global warming and\nelevated ozone (O<sub>3</sub>) levels are gradually\ngaining widespread attention, and exposure to which may cause many\nphysiological changes associated with cardiovascular events such as\nhypertension, cardiomyocyte apoptosis, etc. In addition, ischemic\nheart disease (IHD) is the leading cause of death worldwide. However,\nthe contributions of temperature and O<sub>3</sub>, independently\nor in combination, to IHD mortality are not well understood. This\nstudy employs a two-stage analytical protocol (generalized additive\nmodel followed by meta-analysis) to explore the respective associations\nof temperature and O<sub>3</sub> with IHD mortality, and determine\ntheir possible mediation and interaction effects. Our results suggest\nthat increases of 10 μg/m<sup>3</sup> in O<sub>3</sub> and 1\n°C in temperature at lag01 day are associated with increased\nIHD mortality risks of 0.789% and 0.686%, respectively. O<sub>3</sub> can mediate the relationship between temperature and IHD mortality,\nwith a pooled estimate of 0.140%, while temperature can mediate the\nassociation between O<sub>3</sub> and IHD mortality, with a pooled\nestimate of 0.162%. The additive and multiplicative interaction effects\nof O<sub>3</sub> and temperature were significantly associated with\nIHD mortality. The study findings demonstrate that higher temperature\nand O<sub>3</sub> concentrations can increase human IHD mortality\nrisk through interaction and mediation effects, providing a scientific\nbasis for the synergistic management of temperature and O<sub>3</sub> or associated interventions.