Air pollution and cognitive function: the potential protective effect of physical activity

Physical activity (PA) may mitigate pollution-related cognitive decline while concurrently increasing individuals' exposure to harmful pollutants. Data were obtained from the 2018 China Health and Retirement Longitudinal Study (CHARLS), comprising 17,734 participants aged 45 years or older. Information regarding particulate matter (PM₁, PM_2.5, and PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ozone (O₃) was sourced from the China High Air Pollutants (CHAP) database. The assessment of cognitive function was carried out following the approach utilized in the Health and Retirement Study (HRS). The impact of air pollutants on cognitive function was estimated using the two-stage least squares method, with the ventilation coefficient serving as an instrumental variable. The results indicated that all air pollutants were significantly associated with cognitive function. An interquartile range (IQR) increase in PM₁, PM_2.5, PM₁₀, NO₂, SO₂, and O₃ corresponded to decreases in cognitive function of -0.45 (95% CI: -0.76, -0.13), -0.43 (95% CI: -0.74, -0.13), -0.53 (95% CI: -0.90, -0.16), -0.57 (95% CI: -0.96, -0.17), -0.47 (95% CI: -0.80, -0.14), and -1.06 (95% CI: -1.81, -0.31), respectively. Further stratified analyses revealed that higher levels of PA significantly moderated the association between air pollution and cognitive function, suggesting a potential protective effect. The level of PA was found to modify this association of pollution and cognitive function, with higher PA levels seemingly alleviating the adverse cognitive effects of air pollution. These findings underscore the importance of policies that simultaneously target pollution reduction and promote PA to safeguard cognitive health.