Long-term exposure to air pollution and markers of inflammation, coagulation, and endothelial activation: a repeat-measures analysis in the Multi-Ethnic Study of Atherosclerosis (MESA)

Abstract

Background: Air pollution is associated with cardiovascular disease, and systemic inflammation may mediate this effect. We assessed associations between long- and short-term concentrations of air pollution and markers of inflammation, coagulation, and endothelial activation.

Methods: We studied participants from the Multi-Ethnic Study of Atherosclerosis from 2000 to 2012 with repeat measures of serum C-reactive protein (CRP), interleukin-6 (IL-6), fibrinogen, D-dimer, soluble E-selectin, and soluble Intercellular Adhesion Molecule-1. Annual average concentrations of ambient fine particulate matter (PM2.5), individual-level ambient PM2.5 (integrating indoor concentrations and time-location data), oxides of nitrogen (NOx), nitrogen dioxide (NO2), and black carbon were evaluated. Short-term concentrations of PM2.5 reflected the day of blood draw, day prior, and averages of prior 2-, 3-, 4-, and 5-day periods. Random-effects models were used for long-term exposures and fixed effects for short-term exposures. The sample size was between 9,000 and 10,000 observations for CRP, IL-6, fibrinogen, and D-dimer; approximately 2,100 for E-selectin; and 3,300 for soluble Intercellular Adhesion Molecule-1.

Results: After controlling for confounders, 5 µg/m increase in long-term ambient PM2.5 was associated with 6% higher IL-6 (95% confidence interval = 2%, 9%), and 40 parts per billion increase in long-term NOx was associated with 7% (95% confidence interval = 2%, 13%) higher level of D-dimer. PM2.5 measured at day of blood draw was associated with CRP, fibrinogen, and E-selectin. There were no other positive associations between blood markers and short- or long-term air pollution.

Conclusions: These data are consistent with the hypothesis that long-term exposure to air pollution is related to some markers of inflammation and fibrinolysis.

Conflict of interest statement

Disclosure: The authors report no conflicts of interest.

Figures

FIGURE 1

Associations between IL-6 and long-term pollutant concentrations. Air pollution metrics are annual average concentrations. Percent differences in IL-6 are reported as 5 µg/m3 increase in PM2.5, 0.7·10−6 m−1 increases in black carbon, 40 ppb increase in NOx, and 17 ppb increase in NO2. Model 1 is adjusted for age, race/ethnicity, gender, exam, and site. Model 2 is adjusted for the covariates in Model 1 as well as for education, employment, income, neighborhood SES, recent infection, second-hand smoke exposure, smoking status, alcohol consumption, physical activity, BMI, waist–hip ratio, and splines for calendar time. Model 3 is adjusted for the covariates in Model 2 as well as for hypertension, diabetes, and anti-inflammatory medications.

FIGURE 2

Associations between D-dimer and long-term pollutant concentrations. Air pollution metrics are annual average concentrations. Percent differences are reported as 5 µg/m3 increase in PM2.5, 0.7·10−6 m−1 increases in black carbon, 40 ppb increase in NOx, and 17 ppb increase in NO2. Model 1 is adjusted for age, race/ethnicity, gender, exam, and site. Model 2 is adjusted for the covariates in Model 1 as well as education, employment, income, neighborhood SES, recent infection, second-hand smoke exposure, smoking status, alcohol consumption, physical activity, BMI, waist–hip ratio, and splines for calendar time. Model 3 is adjusted for the covariates in Model 2 as well as for hypertension, diabetes, and anti-inflammatory medications. BMI indicates body mass index.