AIR POLLUTION AND RESPIRATORY DISEASES IN THE TOKYO-YOKOHAMA AREA.

Abstract

Tokyo-Yokohama, Japan, and the surrounding area have a combined population of about ten million. This area, ringed by mountains and a warm ocean current, has a heavy concentration of industry which gives rise to air pollution and smog formation that have become a problem of medical importance. Although so-called asthma (1-4) has been a problem among American military personnel in the area and the evidence would indicate that the disease is caused by industrial air pollution, Japanese physicians have not discovered a similar illness among the indigenous population. The present study was undertaken to determine what differences in respiratory symptoms occur between residents of the TokyoYokohama area and a comparable population in a less heavily industrialized community, Niigata, Japan. Also, it was hoped that, as a result of surveying a large sample of residents of the Tokyo-Yokohama area, cases of TokyoYokohama asthma, as described among American military personnel, might be discovered. facing Tokyo Bay. The heaviest concentration of industry in the Tokyo area is centered in this city, which is notorious for having heavily polluted air. Yokohama, immediately south of Kawasaki, has a population of 1,200,000, and also has heavily polluted air. The populations of the Niigata area and the Tokyo area then represent contrasts from light to heavy air pollution exposure. Approximately 34 per cent of the workers from the oil company in the Tokyo-Yokohama area originally came from the Niigata Plain, where the first oil refinery in Japan was constructed. Each employee was given a questionnaire and instruction sheet before having a physical examination and chest roentgenogram. Information on age, sex, history of allergies, smoking habits, and respiratory symptoms and the effects of change of residence on such symptoms was obtained. To ensure accuracy, the questionnaire was reviewed with the patient before pulmonary function tests were performed. Approximately 10 per cent of the subjects were excluded from statistical analysis because they had had chest surgery or pulmonary diseases of a type that was unrelated to air pollution. To simplify the analysis, patients who had moved from an area of high or low air pollution more than once were also eliminated from statistical consideration. There were very few females; and, because it was so difficult to obtain reliable pulmonary function tests on them, they, also, were excluded from the statistical analysis.