Long-term exposure to airborne particles and arterial stiffness: The multi-ethnic study of atherosclerosis (MESA)

Background: Increased arterial stiffness could represent an intermediate subclinical outcome in the mechanistic pathway underlying associations between average long-term pollution exposure and cardiovascular events. Objective: We hypothesized that 20 years of exposure to particulate matter (PM) ≤ 2.5 and 10 μm in aerodynamic diameter (PM_2.5 and PM₁₀, respectively) would be positively associated with arterial stiffness in 3,996 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) who were seen at six U.S. study sites. Methods: We assigned pollution exposure during two decades preceding a clinical exam (2000-2002) using observed PM10 from monitors nearest participants' residences and PM10 and PM_2.5 imputed from a space-time model. We examined three log-transformed arterial stiffness outcome measures: Young's modulus (YM) from carotid artery ultrasound and large (C₁) and small (C₂) artery vessel compliance from the radial artery pulse wave. All associations are expressed per 10 μg/m3 increment in PM and were adjusted for weather, age, sex, race, glucose, triglycerides, diabetes, waist:hip ratio, seated mean arterial pressure, smoking status, pack-years, cigarettes per day, environmental tobacco smoke, and physical activity. C₁ and C₂ models were further adjusted for heart rate, weight, and height. Results: Long-term average particle exposure was not associated with greater arterial stiffness measured by YM, C₁, or C₂, and the few associations observed were not robust across metrics and adjustment schemes. Conclusions: Long-term particle mass exposure did not appear to be associated with greater arterial stiffness in this study sample.