Pulmonary aspects of nitrogen dioxide toxicity

• Published in: Resources, conservation and recycling conservation and recycling, 1999-07, Vol.27 (1), p.89-97
• Main Authors: Buick, J.B, Lowry, R.C, Magee, T.R.A
• Format: Article
• Language: English
• Subjects: Air; Air pollution; Biological and medical sciences; Environmental pollutants toxicology; Medical sciences; Nitrogen dioxide; Paramagnetic resonance; Respiratory therapy; Respiratory tract; Surface tension; Toxicity; Toxicology
• ISSN: 0921-3449; 1879-0658
• DOI: 10.1016/S0921-3449(98)00088-3

Little is known of the precise location in the respiratory tract where different gaseous pollutants are absorbed. Thus, a model airway was used to study the site and mechanism of nitrogen dioxide (NO 2) absorption. The model consisted of sections of perspex tube, representing the conducting airways, connected in series to a larger compartment of variable surface area, analogous to an ‘alveolar sink’. The inner wall of the tube was lined with a non-woven polymer fabric, moistened with sterile water, to simulate the surface of the tracheobronchial tree where secretions are greater than 90% water. NO 2 gas in nitrogen was passed through the system and its concentration monitored at various positions. It was found that most of the gas reached the larger compartment, confirming that minimal absorption occurs in the upper airways. Thus, NO 2 penetrates the gas exchanging region of the lung. In further experiments, a natural pulmonary surfactant (CUROSURF) was exposed to 5 ppm NO 2 in nitrogen and post-exposure samples were scanned by electron-spin resonance (ESR) to detect the presence of free radicals. The results were negative. In an adjunct to this study, an aqueous solution of CUROSURF was exposed to NO 2 (100 ppm) for 48 h to determine its effect on surface tension. Results have indicated that exposure to NO 2 has a marginal effect on the ability of CUROSURF to lower surface tension.