Chronic Exposure to Nitrogen Dioxide

Abstract

Squirrel monkeys continuously exposed to 1 ppm of nitrogen dioxide (NO₂) for 493 days were challenged five times with monkey-adapted influenza A/PR/8/34 virus. All monkeys exposed to NO₂ produced serum neutralization antibody within 21 days after virus infection, whereas only one control monkey exposed to filtered air showed comparable response. The differences observed in hemagglutination-inhibition antibody titers, body temperatures, respiratory functions, body weights, and hematological values between the experimental and control monkeys were not significant. Histopathologic examination of lung tissues indicated slight emphysema and thickened bronchial and bronchiolar epithelium only in monkeys exposed to NO₂ and challenged with the influenza virus. Transmission election microscopic examination did not disclose any ultrastructural changes that could be attributed to the experimental exposures.