Exposure to Concentrated Coarse Air Pollution Particles Causes Mild Cardiopulmonary Effects in Healthy Young Adults

BACKGROUND: There is ample epidemiologic and toxicologic evidence that exposure to fine particulate matter (PM) air pollution [aerodynamic diameter ≤ 2.5 μm (PM(2.5))], which derives primarily from combustion processes, can result in increased mortality and morbidity. There is less certainty as to the contribution of coarse PM (PM(2.5–10)), which derives from crustal materials and from mechanical processes, to mortality and morbidity. OBJECTIVE: To determine whether coarse PM causes cardiopulmonary effects, we exposed 14 healthy young volunteers to coarse concentrated ambient particles (CAPs) and filtered air. Coarse PM concentration averaged 89.0 μg/m(3) (range, 23.7–159.6 μg/m(3)). Volunteers were exposed to coarse CAPs and filtered air for 2 hr while they underwent intermittent exercise in a single-blind, crossover study. We measured pulmonary, cardiac, and hematologic end points before exposure, immediately after exposure, and again 20 hr after exposure. RESULTS: Compared with filtered air exposure, coarse CAP exposure produced a small increase in polymorphonuclear neutrophils in the bronchoalveolar lavage fluid 20 hr postexposure, indicating mild pulmonary inflammation. We observed no changes in pulmonary function. Blood tissue plasminogen activator, which is involved in fibrinolysis, was decreased 20 hr after exposure. The standard deviation of normal-to-normal intervals (SDNN), a measure of overall heart rate variability, also decreased 20 hr after exposure to CAPs. CONCLUSIONS: Coarse CAP exposure produces a mild physiologic response in healthy young volunteers approximately 20 hr postexposure. These changes are similar in scope and magnitude to changes we and others have previously reported for volunteers exposed to fine CAPs, suggesting that both size fractions are comparable at inducing cardiopulmonary changes in acute exposure settings.