Fatal pulmonary edema due to nitric acid fume inhalation in three pulp-mill workers.

Three young men died of rapidly progressive pulmonary edema of delayed onset after inhalation of fumes from an accidental nitric acid explosion. Electron microscopy revealed altered neutrophils and necrotic endothelial cells in alveolar capillaries. Immunohistochemistry showed small and large serum proteins, including immunoglobulin M, in the edema fluid and hyaline membranes. Increased permeability is a consequence of direct microvascular injury by inhaled nitrogen dioxide. However, our findings, implicating neutrophils and serum-derived mediators in the pathogenesis of the pulmonary edema, are consistent with recent proposals on their roles in the maintenance and/or progression of edema initiated by toxic inhalations.