Waterproofing agents consist of mixtures of solvents, repellents and propellants. Because of a fatality and a number of acute respiratory illnesses in humans following the exposure to a waterproofing agent, the aerosol mixtures were tested in mice. Inhalation of the waterproofing agent resulted in pulmonary collapse and pneumonia in mice. By testing fractions of the waterproofing agent it was determined that the fluororesin repellents in the waterproofing agent were responsible for the acute respiratory illness. The water-repelling agent, such as fluororesin, may counteract the surfactant in the alveoli of the lung and cause diffuse pulmonary collapse followed by acute respiratory distress. The recent substitution of less toxic and environmentally more friendly solvents in waterproofing agents may facilitate fluororesin inhalation by increasing the amount of airborne aerosol and changing the diameter of the aerosol particles. This would explain the apparent recent increase of respiratory symptoms following the use of these agents. In this experiment the mice were exposed intermittently to overcome the CNS effects of the solvents.