Coarse Particulate Matter and Markers of Inflammation and Coagulation in the Multi-Ethnic Study of Atherosclerosis (MESA) Population: A Repeat Measures Analysis

Background: In contrast to fine particles, less is known of the inflammatory and coagulation impacts of coarse particulate matter (PM_10-2:5, particu­late matter with aerodynamic diameter <10 im and >2.5 im). Toxicological research suggests that these pathways might be important processes by which PM_10-2:5 impacts health, but there are relatively few epidemiological studies due to a lack of a national PM_10-2.5 monitoring network. Objectives: We used new spatiotemporal exposure models to examine associations of both 1-y and 1-month average PM_10-2.5 concentrations with markers of inflammation and coagulation. Methods: We leveraged data from 7,071 Multi-Ethnic Study of Atherosclerosis and ancillary study participants 45-84 y of age who had repeated plasma measures of inflammatory and coagulation biomarkers. We estimated PM_10-2.5 at participant addresses 1 y and 1 month before each of up to four exams (2000-2012) using spatiotemporal models that incorporated satellite, regulatory monitoring, and local geographic data and accounted for spatial correlation. We used random effects models to estimate associations with interleukin-6 (IL-6), C-reactive protein (CRP), fibrinogen, and D-dimer, controlling for potential confounders. Results: Increases in PM_10-2.5 were not associated with greater levels of inflammation or coagulation. A 10-μg/m³ increase in annual average PM_10-2.5 was associated with a 2.5% decrease in CRP [95% confidence interval (CI): -5.5, 0.6]. We saw no association between annual average PM_10-2.5 and the other markers (IL-6: -0.7%, 95% CI: -2.6, 1.2; fibrinogen: -0.3%, 95% CI: -0.9, 0.3; D-dimer: -0.2%, 95% CI: -2.6, 2.4). Associations consistently showed that a 10-μg/m³ increase in 1-month average PM_10-2.5 was associated with reduced inflammation and coagulation, though none were distinguishable from no association (IL-6: -1.2%, 95% CI: -3.0 , 0.5; CRP: -2.5%, 95% CI: -5.3, 0.4; fibrinogen: -0.4%, 95% CI: -1.0, 0.1; D-dimer: -2.0%, 95% CI: -4.3, 0.3). Discussion: We found no evidence that PM_10-2.5 is associated with higher inflammation or coagulation levels. More research is needed to determine whether the inflammation and coagulation pathways are as important in explaining observed PM_10-2.5 health impacts in humans as they have been shown tobe in toxicology studies or whether PM_10-2.5 might impact human health through alternative biological mechanisms.