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We performed correlation analysis on the relationship between changes in air pollution and the consultation rate for bronchial asthma in the Yokkaichi region, taking effects of various socioeconomic factors into consideration. The effects of changes in air pollution on the mortality rate due to bronchial asthma were also evaluated. 1. Evaluation of annual changes in the simple correlation coefficient between the consultation rate and the concentration of each pollutant showed no significant correlation with a decrease in the air pollutant concentration in the age group less than 10 years old. However, in the middle-advanced male and female groups aged 40 years and above, the influence of past air pollution still remained. In addition, the partial correlation coefficients between the consultation rate for bronchial asthma and the degree of pollution, socioeconomic factors, and the rate of heavy smokers were calculated. A significant correlation was observed between the consultation rate for the females in each age group and the rate of patients receiving public assistance. 2. The mortality rate due to bronchial asthma in the polluted area increased rapidly with a time lag of several years after the peak of air pollution but decreased gradually thereafter. Presently, the mortality rate in the polluted area is similar to that in the non-polluted (control) area. 3. The mean age of death due to bronchial asthma was elevated because of a decrease in the deaths of those aged less than 60 years. As a result, the difference in the mean age of death due to bronchial asthma between the polluted area and the control area disappeared. With the recent remarkable alleviation of air pollution, the consultation rate and mortality rate due to bronchial asthma have decreased considerably. However, differences are still observed compared with the control area in some age levels so that continuation of monitoring of air pollution as well as consultation and mortality rates is considered necessary.