Effect of polluted Los Angeles air (smog) on lung volume measurements.

The breathing of smog has direct effects on the respiratory tract in addition to direct effects on the eyes and indirect statistical effects on total mortality. The direct respiratory effects were studied in 66 volunteers, 46 of whom had pulmonary emphysema. Measurements were obtained of total vital capacity, timed vital capacity, maximal breathing capacity, residual air, and rate of nitrogenwashout during oxygen breathing. These were used as criteria for the improvement noted when subjects, after breathing either smoggy air or clear Los Angeles air, were allowed to breathe air filtered through activated carbon. The most significant improvement found was the decrease in the volume of residual air noted when subjects with emphysema breathed filtered air for not less than 40 hours. The severity of emphysema was aggravated by smog. No significant changes in lung volume measurements were demonstrated from the breathing of filtered air as compared to smoggy air by essentially normal subjects.