Purpose The present study was conducted to make a continuous study of the influence of air pollution upon asthma-like diseases. It has been said, on the basis of air-pollution reports, that the incidence of asthma-like diseases was higher and the rate of positive reactions to house dust and that of lgE were lower in air-contaminated the air-contaminated areas than in the non-contaminated areas. In this connection, we have been conducting a statistical study of industrial workers and all the grade school children and junior high school students in Kita-Kyushu City for the past 5 years. According to our survey, the above-mentioned condition had been true until 1969 ; however, the incidence and other findings have undergone some changes these five years, during the concentration of contamination has been reduced by half. Method 1) The total of 7,856 people from 108 main industries in Kita-Kyushu city were involved, of whom 400 suspects were examined by interviews and other physical examinations. 2) A11 the grade school children and junior high school students (total of 108 schools) were given physical examinations and the suspects various allergic tests. 3) The contamination was classified according to the area map provided by the Anti-poliution Bureau of Kita-Kyushu City. 4) Asthma-like diseases were classified according to the diagnostic standard designed by the Departments of Internal Medicine, Pediatrics and Hygiene of the Kyushu University Hospital. Results l) With regard to industrial workers, the incidence was higher in highly contaminated areas and this trend showed a gradual decrease as the ages of subjects increased. 2) The rate of positive reactions to house dust and that of lgE were lower in the contaminated areas. 3) With regard to children and and students, the incidence was higher. The age at the onset of the disease seemed to be rather high, but it was not so clear in many of them. 4) Fall dust was reduced by 47% and SOx by 56% during the 5 year period. 5) Typical asthma increased by 1.96%, house dust by 65.5% and lgE also showed a high rate in the contaminated areas during the past 5 years. 6) With regard to psychogenic factors, we examined children's disciplin and personality which were viewed by parents as well as personality evaluated by their school teachers. Many of them showed introversive, hypochondriacal tendencies or had unusual experiences such as separation anxiety. Many children complained of fear and anxiety about contnaminated materials in the highly contaminated areas. Summary Despite the fact that the concentration of contamination was decreased by half and the incidence of atypical asthma decreased, the incidence of typical asthma and the rate of positive reactions to house dust, together with high levels of lgE, have been on the increase .