The effect of tropospheric low-value ozone exposure on the mortality risk of ischemic heart disease and stroke on the example of Yibin (southwestern China).

The association of low-level ozone (O₃) exposure with the mortality risk of ischemic heart disease (IHD) and stroke remains to be investigated. This study aimed to investigate the relationship between low-level O₃ exposure and mortality risk of IHD and stroke in Yibin, a city in southwestern China. A Poisson distribution lagged nonlinear model was used to assess the effect of O₃ exposure on IHD and stroke mortality and to explore the susceptible population according to gender and age subgroups and the susceptible season according to seasonal subgroups and to analyse the health effects under low O₃ exposure compared with high O₃ exposure. The mean O₃ exposure concentration from 2014 to 2020 was approximately 48.3 μg/m3. There was a major lagged effect of O₃ exposure on IHD and stroke. For every 10.0 μg/m³ increase in O₃ concentration, the cumulative risks of death for the two diseases were 1.0211 (95% Confidence Interval [CI]: 1.0064, 1.0358) and 1.0211 (95% CI: 1.0064, 1.0357), respectively. The mortality risks of IHD and stroke for women were 1.0064 (95% CI: 1.0016, 1.0113) and 1.0030 (95% CI: 1.0008, 1.0051), and for those aged > 65 years, they were 1.0082 (95% CI: 1.0026, 1.0139) and 1.0018 (95% CI: 1.0002, 1.0034), and the mortality risks in the warm season were 1.0043 (95% CI: 1.0007, 1.0080) and 1.0038 (95% CI: 1.0005, 1.0072), respectively. The introduction of other pollutants (PM_2.5, PM₁₀, NO₂, CO) to construct a dual-pollutant model showed that the effect of O₃ on the mortality risk of IHD and stroke remained statistically significant. This study consolidates the evidence for a positive correlation between low-level O₃ exposure and the mortality risk of IHD and stroke. The findings provide preliminary exploratory insights into the potential impact of air pollution on these diseases, offering a valuable reference for future research.