Prospective Study of Ambient Particulate Matter Exposure and Risk of Pulmonary Embolism in the Nurses’ Health Study Cohort

BACKGROUND: Pulmonary embolism (PE) is the most serious manifestation of venous thromboembolism and a leading cause of sudden death. Several studies have suggested associations of venous thromboembolism with short-term particulate matter (PM) exposure; evidence on long-term PM and traffic exposure is mixed. OBJECTIVES: We examined the association of long-term exposure to PM(2.5), PM(2.5–10), and PM(10) (PM with diameter of ≤ 2.5, 2.5–10, and ≤ 10 μm) and distance to roadways with overall incident PE and with PE subtypes in a cohort of U.S. women. METHODS: The study included 115,745 women from the Nurses’ Health Study, followed from 1992 through 2008. Incident PE cases were self-reported biennially. Nonidiopathic PE were cases for which the medical record revealed an underlying health condition related to PE (i.e., surgery, trauma, or malignancy); idiopathic PE were cases with no such history. We used spatiotemporal models combining spatial smoothing and geographic covariates to quantify exposure at residential addresses, and Cox proportional hazards models to calculate hazard ratios (HR) and 95% confidence intervals (CIs). RESULTS: PM(2.5) averaged over 1 month (HR = 1.22; 95% CI: 1.04, 1.44) or 12 months (HR = 1.17; 95% CI: 0.93, 1.48) was associated with incident PE, after adjusting for known risk factors and PM(2.5–10). Equivalent analyses restricted to PE subtypes showed a positive association for PM(2.5) with nonidiopathic PE, but not with idiopathic PE. We did not find evidence of an association between distance to roadways and PE risk. CONCLUSIONS: We provide evidence that PM in the prior 1 and 12 months is associated with PE risk. Our results also suggest that women with underlying health conditions may be more susceptible to PE after PM exposure. CITATION: Pun VC, Hart JE, Kabrhel C, Camargo CA Jr, Baccarelli AA, Laden F. 2015. Prospective study of ambient particulate matter exposure and risk of pulmonary embolism in the Nurses’ Health Study cohort. Environ Health Perspect 123:1265–1270; http://dx.doi.org/10.1289/ehp.1408927