SO2(35S Labeled) Absorption by the Nose and Mouth Under Conditions of Varying Concentration and Flow

Abstract

Sulfur dioxide³⁵S (³⁵SO₂) was administered to the surgically isolated upper airways of anesthetized dogs via a mask with separate connections to the nose and mouth. The ³⁵SO₂ that passed through the upper airways was monitored continuously; nearly complete removal could be measured to within several hundredths of a percent. Nasal uptake of the incoming gas (1 to 50 ppm) exceeded 99% at a flow of 3.5 liters/min and fell only several percent when flow was increased tenfold (1, 10 ppm). Uptake by the mouth averaged more than 95% at a flow of 3.5 liters/min (1, 10 ppm) but fell to under 50% when flow was increased tenfold. Following penetration of the mouth or nose by ³⁵SO₂, desorption of the gas from the mucosa could be demonstrated more than 25 minutes after the end of exposure.