Health effects of volcanic air pollution--an analysis of the national health insurance

Abstract

Using the national health insurance bills covering the one-year period from January through December 1987, the morbidity figures for respiratory diseases, conjunctivitis and dermatitis were compared among four local districts; Ushine, Kaikata, Kunugibaru and Shinjo, in the city of Tarumizu. The former two districts are 10 km south-east of Mt. Sakurajima supposedly experience higher volcanic ash exposure compared to the latter two located 10 to 15 km from this volcano. Results obtained are as follows; 1) Age-adjusted rates of patients' consultations and existing patients were apparently higher in the Ushine and Kaikata districts than in the Kunugibaru and Shinjo districts for non-infectious or infectious respiratory diseases and the common cold. For the rates of other diagnostic categories of disease, i.e., rhinitis, other respiratory diseases, conjunctivitis and dermatitis, a difference between the district was not clearly noted. These figures are suggestive of an association of volcanic air pollution with an increased number of outpatient consultations for respiratory problems. 2) Variations of monthly clinical consultations for patients with diagnoses of non-infectious or infectious respiratory diseases and the common cold showed a seasonality, being highest in winter and lowest in summer, while another seasonality, highest in summer and lowest in winter, was proved in the variation of monthly clinical consultations for patients with dermatitis. Few or no stable seasonalities were shown in the variations of monthly clinical consultations for patients with the other diseases, studied, rhinitis, other respiratory diseases and conjunctivitis. In addition, the variations in the monthly averages of sulfur dioxide concentrations showed a stable seasonality with the highest peak in winter and the lowest in summer but there was no stable seasonality in the monthly variations of total suspended particles at the place in Arimura for which air pollution data were available. These facts suggest that in the area exposed to volcanic air pollution, the seasonal variation in the number of monthly clinical consultations for respiratory problems is partly modified by the exposure levels of sulfur dioxide rather than total suspended particles, although no adjustments were made for climatologic factors. 3) A few patients diagnosed as having "pneumoconiosis" were found in the Ushine and Kaikata districts. However, it is difficult to interpret these cases without information about occupational and other risk factors for the development of pneumoconiosis.