Respiratory response to iodine vapor alone and with sodium chloride aerosol

Respiratory function measurements in guinea pigs were used to evaluate the irritant response to 1-h exposures to iodine vapor and the effect of 10 mg/m(3) submicrometer sodium chloride aerosol on this response. Iodine alone at 0.5 ppm produced no detectable response. Concentrations of 3-4 ppm increased resistance and decreased frequency and minute volume. The response appeared to be upper respiratory. At 7 ppm there was also a decrease in compliance, suggesting pulmonary effects. The response was potentiated by the sodium chloride aerosol. Increased resistance and decreased compliance and frequency were observed at 0.4 ppm. The changes at concentrations of 1-2 ppm were greater when the aerosol was present and included a decrease in compliance. The comparative effects of the sodium chloride aerosol on iodine, sulfur dioxide, and formaldehyde are discussed.