The air pollutants can be classified into the irritant gas and the asphyxial gas, and the irritant gas is closely related to the otorhinolaryngological diseases. The common irritant gases are nitrogen oxides, sulfur oxides, hydrogen carbon compounds, and the potent and irritating PAN (peroxy acyl nitrate) which is secondarily liberated from photosynthesis. Those gases adhers to the mucous membrane to result in ulceration and secondary infection due to their oxidizing power. 1) Sulfur dioxide gas : Sulfur dioxide gas has the typical characteristics of the air pollutants. Because of its high solubility it gets easily absorbed in the respiratory tracts, when the symptoms and signs by irritation become manifested initially and later the resistance in the respiratory tracts brings about pulmonary edema and respiratory paralysis of central origin. Chronic exposure to the gas leads to rhinitis, pharyngitis, laryngitis, and olfactory or gustatory disturbances. 2) Carbon monoxide : Toxicity of carbon monoxide is due to its depriviation of the oxygen carrying capacity of the hemoglobin. The degree of the carbon monoxide intoxication varies according to its concentration and the duration of inhalation. It starts with headache, vertigo, nausea, vomiting and tinnitus, which can progress to respiratory difficulty, muscular laxity, syncope, and coma leading to death. 3) Nitrogen dioxide : Nitrogen dioxide causes respiratory disturbances by formation of methemoglobin. In acute poisoning, it can cause pulmonary congestion, pulmonary edema, bronchitis, and pneumonia, It causes also strong irritation on the eyes and the nose. In chronic poisoning, it causes chronic pulmonary fibrosis and pulmonary edema. 4) Ozone : It has offending irritating odor, and causes dryness of nasopharyngolaryngeal mucosa, headache and depressed pulmonary function which may eventually lead to pulmonary congestion or edema. 5) Smog : The most outstanding incident of the smog occurred in London from December 5 through 8, 1952, because of which the mortality of the respiratory diseases increased fourfold. The smog was thought to be due to the smoke produced by incomplete combustion and its byproduct the sulfur oxides, and the dust was thought to play the secondary role. In new sense, hazardous is the photochemical smog which is produced by combination of light energy and the hydrocarbons and oxidant in the air. The Yonsei University Institute for Environmental Pollution Research and Department of Otolaryngology launched a project to determine the relationship between the pollution and the medical, ophthalmological and otorhinopharyngological disorders. The student(469) of the ""S"" Technical School in the most heavily polluted area in Pusan(Uham Dong district) were compared with those(345) of ""K"" High School in the less polluted area. The investigated group had these with subjective symptoms twice as much as the control group, 22.6%(106) in investigated group and 11.3%(39) in the control group. Among those symptomatics students of the investigated group. There were 29 with respiratory symptoms(29%), 22 with eye symptoms(21%), 50 with stuffy nose and rhinorrhea(47%), and 5 with sore throat(5%), which revealed that more than half the students(52%) had subjective symptoms of the rhinopharyngological aspects. Physical examination revealed that the investigated group had more number of students with signs than those of the control group by 10%, 180(38.4%) versus 99(28.8%). Among the preceding 180 students of the investigated group, there were 8 with eye diseases(4.4%), 1 with respiratory diseases(0.6%), 97 with rhinitis(54%), and 74 with pharyngotonsillitis(41%), which means that 95% of them had rhinopharyngeal disease. The preceding data revealed that the otolaryngological diseases are conspicuously outnumbered in the heavily polluted area, and that there must be very close relationship between the air pollution and the otolaryngological disease, and the anti-pollution measure is urgently needed.