[Trends of air pollution versus those of consultation rate and mortality rate for bronchial asthma in individuals aged 40 years and above in the Yokkaichi region].

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.

Effects of exposure to NO2 or SO2 on bronchopulmonary reaction induced by Candida albicans in guinea pigs.

The effects of NO2 or SO2 on the bronchopulmonary reactions induced by Candida albicans in guinea pigs were evaluated. Thirty-six guinea pigs (3 groups of 12 animals each) were sensitized with intraperitoneal injection of 10 mg of C. albicans, given twice. Two groups of animals were exposed to about 5 ppm of NO2 or SO2 for 4 h/d, 5 d/wk; this exposure was conducted a total of 30 times during the study. The third group served as the control and was not exposed to these pollutants. Two weeks after the second sensitization, all the animals were subjected to inhalation exposure to C. albicans. For 42 h after the antigen challenge, the respiratory rates and expiration/inspiration ratios of the animals were automatically monitored. The number of animals showing tachypnea was significantly higher in the NO2 exposure group than in the control from 15 h after antigen challenge. In the SO2 exposure group, the number of animals showing prolonged expiration or prolonged inspiration, or both, was significantly higher than that in the control group, and the symptoms were observed from approximately 15 h after antigen challenge. These findings showed that delayed-type dyspneic symptoms in guinea pigs were increased by exposure to NO2 or SO2, although the symptoms and degree of dyspnea were different for the two gases.

Procedure for evaluating changes in respiratory symptoms of experimentally asthma-induced guinea pigs by a personal computer.

An automated system was developed for evaluating changes in respiratory symptoms in guinea pigs over a long period with a personal computer. The data on breathing curves obtained with a body plethysmograph were analyzed to determine respiratory rate, expiration/inspiration ratio, ventilation ratio, and other parameters. With this system, respiratory changes in guinea pigs, such as increase or decrease of respiratory rate, expiration/inspiration ratio, and ventilation ratio, and death of animals could be easily observed. Investigation of delayed respiratory response to Candida albicans in sensitized guinea pigs and of the effects of SO2 or NO2 exposures on its response was carried out using this system. Respiratory changes in delayed respiratory response were mostly increased respiration rate and succeeding expiratory prolongation being noted just before death. In the influences of SO2 or NO2 exposure on delayed respiratory response, increase of respiratory rate in NO2 and expiratory and inspiratory prolongation in SO2 were found. This system should prove useful for evaluating changes in respiratory symptoms due to toxic agents, medicines, and air pollutants in small animals.