The Responses of Animals Inhaling Nitrogen Dioxide For Single, Short-term Exposures

Abstract

Rats and dogs were exposed for single 5- to 60-minute periods to various concentrations of NO₂. Changes in lung to body weight ratios of rats correlated directly with the severity of exposure to NO₂. The kidney to body weight ratios of rats, the hematocrits, and blood platelet counts of dogs were of little or no value in evaluating the severity of NO₂ exposures. Dogs had only mild toxic signs at NO₂ concentrations which caused pulmonary edema in rats. Based on lung to body weight ratios of rats, the responses of dogs, and the pathological changes found in exposed animals, the threshold concentrations of NO₂ found were 104, 65, and 28 ppm for 5, 15, and 60 minutes, respectively.