Morphologic effects of a sulfur(IV) aerosol on the nasal cavity of beagle dogs.

Morphologic changes were observed in nasal cavities of beagle dogs after long-term exposure to a respirable sulfur(IV) aerosol at a concentration equivalent to a sulfur dioxide (SO2) concentration of 0.6 mg/m3. The changes were characterized by a thickened epithelial layer resulting from epithelial proliferation, by a loss of secretory material, and by moderate mononuclear cell infiltration.