Concentrated ambient air particles induce mild pulmonary inflammation in healthy human volunteers

We tested the hypothesis that exposure of healthy volunteers to concentrate d ambient particles (CAPS) is associated with an influx of inflammatory cel ls into the lower respiratory tract. Thirty-eight volunteers were exposed t o either filtered air or particles concentrated from the immediate environm ent of the Environmental Protection Agency (EPA) Human Studies Facility in Chapel Hill, North Carolina. Particle concentrations in the chamber during the exposures ranged from 23.1 to 311.1 mu g/m(3). While in the exposure ch amber, volunteers alternated between moderate exercise (15 min) and rest (1 5 min) for a total exposure time of 2 h. There were no symptoms noted by vo lunteers after the exposure. Similarly, there were no decrements in pulmona ry function. Eighteen hours after exposure, analysis of cells and fluid obt ained by bronchoalveolar lavage showed a mild increase in neutrophils in bo th the bronchial and alveolar fractions in those individuals exposed to CAP S (8.44 +/- 1,99 and 4.20 +/- 1.69%, respectively, in those with the greate st exposure) relative to filtered air (2.69 +/- 0.55 and 0.75 +/- 0.28%, re spectively). Blood obtained 18 h after exposure to CAPS contained significa ntly more fibrinogen relative to samples obtained before exposure. We concl ude that ambient air particles are capable of inducing a mild inflammation in the lower respiratory tract, as well as an increased concentration of bl ood fibrinogen.