Age and sex differences in the effects of short- and long-term exposure to air pollution on endothelial dysfunction

Abstract

Background: The effects of air pollution on endothelial function remain unclear across populations. We aimed to use brachial artery flow-mediated dilatation (FMD) to identify demographic differences in the effects of air pollution exposure on endothelial dysfunction.

Methods: We measured FMD in 850 participants from October 2016 to January 2020. Location-specific concentrations of fine particulate matter < 2.5 μm aerodynamic diameter (PM_2.5), inhalable particulate matter < 10 μm aerodynamic diameter (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and ozone (O₃) measured by fixed ambient air monitoring stations were collected for short- and long-term exposure assessment. Multiple linear regression models and restricted cubic splines were used to assess the associations before and after stratification by age and sex.

Results: This study eventually included 828 participants [551 (66.5%) younger than 65 years and 553 (66.8%) men]. Each 10 µg/m³ increase in 7-day exposure to PM_2.5 and PM₁₀ was significantly linearly associated with a 0.07% (β = -0.07, 95% CI: -0.13 to -0.004) and 0.05% (β = -0.05, 95% CI: -0.10 to -0.004) decrease in FMD in the fully adjusted model. After full adjustment, long-term exposure to all air pollutants was significantly associated with impaired FMD. Each 10 µg/m³ increase in long-term exposure to PM_2.5 and PM₁₀ was significantly associated with a -0.18% (95% CI: -0.34 to -0.03) and - 0.23% (95% CI: -0.40 to -0.06) change in FMD, respectively. After stratification, the associations of lower FMD with long-term exposure to PM_2.5, PM₁₀, SO₂, NO₂, and CO significantly persisted in men and participants younger than 65 years instead of women or older participants. For short-term exposure, we observed differences consistent with long-term exposure and a stronger effect of 7-day exposure to SO₂ in men due to a significant interaction effect.

Conclusion: Short- and long-term exposure to different air pollutants are strongly associated with decreased endothelial function, and susceptibility to air pollution varies significantly with age and sex.

Keywords: Air pollution; Endothelial dysfunction; Flow-mediated dilatation.

Fig. 1

Associations between long-term exposure to (A) PM_2.5, (B) PM₁₀, (C) SO₂, (D) NO₂, (E) CO, (F) O₃ and flow-mediated dilation (%).^{a, b} Note: ^a PM_2.5, fine particulate matter with aerodynamic diameter < 2.5 μm; PM₁₀, inhalable particulate matter with aerodynamic diameter < 10 μm; SO₂, sulfur dioxide; NO₂, nitrogen dioxide; CO, carbon monoxide; O₃, ozone; 95% CI, 95% confidence interval. ^b Model adjusted for age group (< 65 years and ≥ 65 years), sex, body mass index, smoking status, cardiovascular disease, hypertension, diabetes mellitus, resting heart rate, and low-density lipoprotein cholesterol