Effects of Photochemical Smog on Alveolar Lung Tissues of Young and Old Mice — An Electron Microscope Study

Abstract

Photochemical smog was produced by irradiating a mixture of propylene (8 ppm), nitric oxide (2.8 ppm), carbon monoxide (25 ppm) and water vapor (20%) with ultraviolet lamps in the 1000 cu. ft. reaction chamber of the California Vehicle Pollution Laboratory. The total oxidant concentration and reaction patterns approximated those of a heavy smog day. Male A, Swiss-Webster and C-57 strains of mice exposed for 3-4 hours showed ultrastructural alterations of alveolar lung tissue similar to the heavy natural smog exposures (Bils, 1966). Wall cells became highly vacuolated and some lining membranes disrupted in 8-month-old mice, but only temporarily. Delaying sacrifice only 12 hours allowed the lungs to return to normal. However, permanent changes occured in 15-month-old mice. Fair recovery of smog-disrupted alveolar and capillary lining cells occured, but few wall cells remained. More extensive disorganization of wall cell cytoplasm and lining membranes was seen when the 20-month-old mice breathed synthetic smog; delayed sacrifice revealed further damage and cell debris in the alveoli.