Abstract
The effect of inhalation of sulfuric acid (H2SO4) aerosol on respiratory deposition of radiolabeled streptococcus aerosol was investigated in guinea pigs. A 60 minute exposure to 3020 µgm/m3 H2SO4 (1.8 µxm CMD) resulted in a 60% greater total respiratory deposition rate than control animals and a proximal shift in the regional pattern of deposition to the nasopharynx. Dose-response experiments revealed that a concentration of 30 µgm/m3 H2SO4 (0.25 µm CMD) also induced a proximal shift in the regional pattern of particle deposition but in this instance the shift was to the trachea. The interrelationship between mass concentration of H2SO4 and its particle size to the interpretation of these results is discussed. A hypothesis concerning the relationship of these data to previously reported respiratory physiologic effects of H2SO4 inhalation and to a pathophysiologic mechanism which may underlie effects attributed to sulfur oxides by epidemiologic studies is described.