Abstract Background Long-term exposure to PM2.5 and low physical activity are independently associated with an increased risk of cardiovascular disease (CVD). However, there is limited research investigating the combined effects of PM2.5 exposure and physical activity on CVD risk. Purpose This study aims to examine the interactive effects of long-term PM2.5 exposure and physical activity on incident CVD and mortality. Methods The Prospective Urban Rural Epidemiology (PURE)-China cohort study is a population-based cohort study recruiting participants aged 35–70 years in 12 provinces between 2005 and 2009. PM2.5 exposure was estimated using a Bayesian hierarchical model. Information on physical activity was recorded using the long-form International Physical Activity Questionnaire (IPAQ) and converted to metabolic equivalent task (MET)-minutes per week. Participants were divided into high and low PM2.5 exposure groups by the median concentration (47.70 μg/m3). The primary outcome was a composite of all-cause mortality and major cardiovascular events. Cox frailty models and restricted cubic splines were used to assess associations. Interaction effects were evaluated using measures of multiplicative and additive interaction, including the relative excess risk due to interaction (RERI) and the proportion attributable to interaction (AP). Results The PURE-China study recruited 47 931 participants, of whom 39 970 are eligible for this analysis. During the median follow-up period of 11.9 years (IQR: 9.6-12.7), 1316 major cardiovascular events and 1084 all-cause deaths occurred in the low-exposure group, compared to 1859 major cardiovascular events and 1048 all-cause deaths in the high-exposure group. In low-exposure areas, higher total physical activity significantly reduced the risk of composite outcome (HR: 0.84, 95%CI: 0.73–0.97, p trend=0.012) and major cardiovascular events (HR: 0.80, 0.67–0.95, p trend=0.022). However, in high-exposure regions, physical activity showed no protective effect for the composite outcome (HR: 0.97, 0.85–1.09, p trend=0.551) and major cardiovascular events (HR: 0.98, 0.85–1.13, p trend=0.864). Higher non-recreational physical activity reduced the risks of composite outcome and major CVD in low-exposure areas but provided no benefit in high-exposure regions (p interaction=0.011, 0.024, respectively). Significant antagonistic interaction was observed between high PM2.5 and low non-recreational physical activity for composite outcome (RERI: -0.215, 95%CI: -0.406 to -0.024; AP: -0.155, 95%CI: -0.294 to -0.017). Conclusion Long-term exposure to high PM2.5 concentrations diminishes the cardiovascular benefits of physical activity, particularly non-recreational activities. These findings underscore the need for tailored physical activity guidelines and air quality interventions in heavily polluted regions to maximize public health benefits.
Hao et al. (Sat,) studied this question.