Inflammatory lung injury after bronchial instillation of air pollution particles

Epidemiologic investigation has established an association between exposure to particulate matter (PM) and human health in the Utah Valley. Reduction of particle mass during the temporary closure of a local steel mill was ass ociated with diminished morbidity and mortality. We tested the hypothesis t hat the biologic effect of PM would reflect findings of epidemiology with a greater injury after exposure to an equal mass of particles from those yea rs in which the mill was in operation. Filters containing PM were collected prior to closure of the steel mill, during the closure, and after its reop ening. Aqueous extracts of the filters were prepared. One of three extracts (500 mug) was instilled through the bronchoscope into the lungs of nonsmok ing volunteers. Twenty-four hours later, the same subsegment was savaged. E xposure to aqueous extracts of PM collected before closure and after reopen ing of the steel mill provoked a greater inflammatory response relative to PM extract acquired during the plant shutdown. This is the first demonstrat ion that pulmonary effects after experimental exposure of humans to PM can correlate with health outcomes observed in epidemiologic studies of the sam e material under normal exposure conditions. Findings suggest that mass may not be the most appropriate metric to use in assessing health effects afte r PM exposure but rather specific components must be identified and assesse d.