Effects of major air pollutants on cognitive function in middle-aged and elderly adults: Panel data evidence from China Health and Retirement Longitudinal Study.

Background: Although numerous studies have discussed about the impact of air pollution on cognitive function, a consensus has yet to be reached, necessitating further exploration of their relationship. The aim of this study is to reveal the effects of major air pollutants on cognitive function in Chinese middle-aged and older adults, while considering the lagged effects of pollution.

Methods: Panel data were constructed by integrating the air pollutants concentration (particulate matter diameter ≤1 µm (μm) (PM₁), PM_2.5, PM₁₀, nitrogen dioxide (NO₂), and ozone (O₃)) among 28 provinces in China and the personal characteristics from China Health and Retirement Longitudinal Study participants during the period of 2011-2015. To explore the effects of single pollutants and their interactions on cognitive function, panel linear regression using ordinary least squares method was employed, and first-order lag effects (two-year interval) of air pollution were introduced into the models.

Results: Our study revealed that, after adjusting for confounding factors, higher levels of particulate matter (PM₁, coefficient (Coef.) = -0.093, P = 0.001; PM_2.5, Coef. = -0.051, P = 0.001; PM₁₀, Coef. = -0.030, P = 0.001) and NO₂ (Coef. = -0.094, P = 0.006) were associated with lower cognitive function scores among the participants. Moreover, the interaction between the five major pollutants exhibited a negative effect on cognitive function(Coef. = -2.89, P = 0.004).

Conclusions: PM₁, PM_2.5, PM₁₀ have detrimental effects on the cognitive function of middle-aged and elderly adults in China, where increasing particle diameter correlates with a less negative impacts, providing theoretical underpinnings for the formulation of environmental protection policies.