This protocol contains studies evaluating the biochemical mechanism by which oxidizing air pollutants produce deleterious effects. The specific aims are: 1. To determine the possible role of malonaldehyde in ozone toxicity including: a. assessment of the fluorescence of extracts of lung fractions as an indication of lipid peroxidation. b. further evaluation of the interaction of malonaldehyde with nuclear contents related to its possible role in mutaganesis by ozone. c. preliminary studies of the possibility that malonaldehyde may crosslink collagenous constituents of the lung. d. determination of the protein viscosity of lung and alveolar macrophage cell membrane protein which may be increased as a result of malonaldehyde crosslinking. 2. To evaluate the possibility that ozone inhalation results in the oxidation of tryptophan with the resultant formation of N- formylkynurenine. 3. To determine whether the potentiation of pulmonary bacterial infections by ozone and nitrogen dioxide might be due to an interference in the ability of alveolar macrophages and granulocytes to produce active bacteriocidal species such as the superoxide anion radical. 4. To perform further studies evaluating whether ozone exposure might protentiate subsequent membrane effects of activated complement, particularly in relation to histamine release as a basis for the increased asthma attack rate observed in association with photochemical air pollution. 5. To study the combined effects of ozone and nitrogen dioxide.