Association between long-term exposure to ambient air pollutants and excessive daytime sleepiness in Chinese rural population: The Henan Rural Cohort Study

Background: Excessive daytime sleepiness is associated with many adverse consequences, including cardiovascular diseases and mortality. Although exposure to air pollution has been suggested in connection with excessive daytime sleepiness, evidence in China is scarce. The study aimed to explore the association between long-term exposure to air pollution and excessive daytime sleepiness in rural China. Methods: A lot of 27935 participants (60% females) from the Henan Rural Cohort Study were included in this analysis. A satellite-based spatiotemporal model estimated a 3-year average air pollution exposure to NO₂ (nitrogen dioxide), PM₁ (particulate matter with aerodynamic diameters not more than 1 μm) and PM_2.5 (particulate matter with aerodynamic diameters not more than 2.5 μm) at the home address of participants before the baseline survey. Logistic regression was used to evaluate the odds ratio and 95% confidence interval between long-term air pollution and excessive daytime sleepiness. Results: The average concentrations of NO₂, PM₁ and PM_2.5 during three years preceding baseline survey were 38.22 μg/m³, 56.29 μg/m³ and 72.30 μg/m³. Exposure to NO₂, PM₁ and PM_2.5 were all associated with excessive daytime sleepiness. Each 1 μg/m³ increment of NO₂, PM₁ and PM_2.5 were related to a 20% (OR: 1.20, 95% CI: 1.13–1.27), 10% (OR: 1.10, 95% CI: 1.05–1.16) and 17% (OR: 1.17, 95% CI: 1.10–1.23) increase of the prevalence of excessive daytime sleepiness. Conclusion: The study demonstrated that long-term exposure to NO₂, PM₁ and PM_2.5 were all associated with excessive daytime sleepiness. The impact of air pollution should be considered when treating individuals with excessive daytime sleepiness.