Dr. George Leikauf and coworkers at the University of Cincinnati Medical Center examined the mechanism by which aldehyde inhalation can alter breathing patterns and damage cells lining the airways. Emissions from motor vehicles using gasoline and diesel fuels add to the outdoor levels of aldehydes, including formaldehyde and acrolein, which are known irritants of the respiratory tract. The investigators prposed to examine whether airway constriction due to exposure to aldehydes is caused by damage to airway cells, by the entry of white blood cells into the lungs, or both. Guinea pigs were exposed for either 2 or 8 hours to 0.1 to 31 parts per million (ppm) formaldehyde or 0.3 to 3 ppm acrolein, concentrations ranging from those that can occur at work and in homes to very high levels. Immediately after exposure, they tested each animal's lung function to determine the extent of airway constriction caused by either aldehyde. After exposure, they also performed a series of more sensitive tests that measured lung function in which they treated the animals with a drug that provokes airway constriction. Cells and fluids were also washed from the animals' lungs and examined for white blood cells and for specific products of cell damage, called eicosanoids. Finally, the investigators added acrolein to cultures of airway cells obtained from cows and humans and then tested the culture fluids for eicosanoids.