Abstract
Clinical Study: The subjects examined were children from primary schools at different areas polluted by sulfurous acid gas, dust or exhaust gas, and also those at heavy or moderately polluted areas in Tokyo. Laborers from a mine (silica), fertilizer (sulfurous acid gas) and brick (dust) factories were also examined. The investigation was performed with indirect laryngoscopy and phonic examinations. The children were followed up for two or three years.
No significant differences on the results of laryngoscopy and phonic examinations were found regarding the origin and density of air pollution. The number of children with redness and swelling of vocal cords at air polluted areas was found larger than that of controls. However, this was noted only in the first year. Abnormal vocal cords in laborers from the mine and factories were found more frequently than those in children from air polluted areas. The phonic examinations revealed no evidence of phonic disorders even in the environment of air pollution.
Experimental Study: Ten cats were exposed to sulfurous acid gas and 15 rabbits to ozone. Each gas was given to the animals by inhalation. Their larynx and trachea were obtained and observed under light and electron microscopes.
Cat vocal cords showed epithelial metaplasia, edema in connective tissues with infiltration of neutrophils and partially ulcer formation. A cyst-like bulging was observed at the tip of cilium on the ciliated epithelium of rabbits. A disarrangement of cilia was also noted.
