The airway effects of a 4-hr exposure (via a Plexiglas hood) to 1.6 ppm nitric acid vapor were evaluated in seven normal and seven allergic sheep, i.e., animals that have a history of reacting with bronchospasm to inhalation challenge with Ascaris suum antigen. The nitric acid vapor was generated by ultrasonic nebulization of a 2% nitric acid solution. Airway effects were assessed by measuring the change in specific pulmonary flow resistance before and after a standard inhalation challenge with 2.5% carbachoi aerosol. Nitric acid exposure did not produce bronchoconstriction in either group. Pre-exposure increases in specific pulmonary flow resistance after carbachoi Inhalation were 68% (SD ± 13%) and 82% (SD ± 35%) for the normal and allergic sheep, respectively, Within 24 hr, the largest postexposure increases in specific pulmonary flow resistance for the normal and allergic sheep were 108% [SD ± 51% (P<.06)] and 175% [SD ± 87% (P<.02)], respectively. We conclude that a short-term exposure to nitric acid vapor at levels below the industrial threshold limit (2 ppm), produces airway hyperreactivity to aerosolized carbachoi in allergic sheep.
ASJC Scopus subject areas
- Environmental Chemistry
- Environmental Science(all)
- Public Health, Environmental and Occupational Health
- Health, Toxicology and Mutagenesis