Dr. Leikauf and colleagues at the University of Cincinnati Medical Center examined the potential of the secondary products produced from the reaction of ozone with the fluids and the cell membrane of airway epithelial cells to cause biochemical effects. The investigators prepared aldehydes and hydroxyhydroperoxides of different carbon chain lengths. They tested these compounds and hydrogen peroxide in cultures of human airway epithelial cells grown from tissue explants. Cells were prelabeled with [3H]-labeled arachidonic acid, which is a major, fatty acid component of the cell membrane attached to a radioactive form of hydrogen. The researchers measured the amount of radioactive metabolites of arachidonic acid released into the culture medium; these metabolites, called eicosanoids, are believed to play an important role in airway reactivity, cellular responses to inhaled pollutants, and asthma.