Nitrogen dioxide has been known as one of the most prevalent air pollutants in urban and industrial ambient environment. Toxicologically, nitrogen dioxide is a noxious gas with prominent irritant property.
A strong irritating effect on the respiratory epithelium and the formation of methemoglobin are the main toxicity of nitrogen dioxide. Clinically, pulmonary edema and congestion are believed to be a main cause of illness and death.
Author attempted this study to clarify the effects of nitrogen dioxide inhalation on the oxygen consumption of the respiratory epithelium of the lung. Four sites of the respiratory tract, nasopharynx, trachea, main bronchus and-lung were chosen as sampling area. Nitrogen dioxide of concentration of 1, 000 ppm, 500 ppm and 100 ppm were inhaled by rats for 3 hours, 6 hours 30 hours respectively. Warburg´s manometric method was employed in the measurement of tissue oxygen consumption.
The findings observed are as follows:
1. The oxygen consumption rates were depressed in all experimental groups.
2. While the nasopharynx was suffering a slight functional damages in terms of oxidative process, the trachea and main bronchus manifested moderate degree of functional damage. The .most severe damages caused by grave depression of tissue oxygen consumption were found in the lung tissue.
3. It has been clarified that the duration of exposure is more determinant than the magnitude of NO₂ concentration in the stimulus-response relationship.
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