The Mount Sakurajima volcano in Kyushu, Japan, is proximal to a large residential area, and it emits an enormous amount of volcanic ash during frequent eruptions. In our previous study, we investigated, for the first time, respiratory effects of chronic exposure to volcanic ash. The study demonstrated a low prevalence of respiratory symptoms, even in the area of highest exposure; only a slight excess prevalence of symptoms appeared to be associated with exposure to volcanic ash. To confirm the findings of our previous study, the prevalence study of chronic respiratory symptoms for residents was repeated in Kanoya and Tashiro, which are located 25 and 50 km, respectively, from the crater of Mt. Sakurajima. The concentration of suspended particulate matter in Kanoya frequently exceeded the national environmental quality standards and, during summer and winter, was 2-3 times higher than that found in Tashiro. Women who were 30-59 y of age and who had resided in Kanoya or Tashiro for more than 3 y completed a modified ATS-DLD questionnaire. The prevalence of nonspecific respiratory disease was low, i.e., 6.5% in Kanoya and 6.2% in Tashiro; similar prevalences were found in women who had never smoked. When we restricted the analysis to individuals without a history of occupational exposure to dusts and who had no exposure to passive smoking, there was a slightly higher prevalence of nonspecific respiratory disease in Kanoya than Tashiro, but the difference was not significant. Eye symptoms were equally prevalent in the two areas.(ABSTRACT TRUNCATED AT 250 WORDS)
The chronic pulmonary effects of exposure to volcanic ash were investigated by conducting a cross-sectional epidemiological study of 2,006 women between 30 and 59 yr of age who lived in three areas subjected to different levels of airborne ash. In the three areas prevalences of chronic bronchitis and other respiratory symptoms were so low that volcanic ash did not seem to be a major cause of respiratory disease. In the highly exposed area, however, 9.9% of the women experienced symptoms of one or more respiratory diseases, while 6.4% of the women in the medium- and 5.4% of the women in the low-exposure area had these symptoms. Prevalences of each disease and symptom increased as total suspended particulate level increased, suggestive of an association of mild respiratory symptoms with volcanic ash.
Mount Sakurajima in the south of the Kyushu Island of Japan erupts hundreds of times a year and continuously emits large amounts of ash. More than a million people live under this ash plume, and there is considerable concern about the possible effects of this on their health. We have studied the physicochemical characteristics and in vitro effects of airborne ash collected at 8 km from the crater. More than 30% of the ash was found to be SiO2 (w/w) with most of the particles within the respirable size range. The ash did not inhibit the colony formation of V79-4 cells and failed to activate complement or generate chemotactic factor activity in samples of fresh human serum. It was minimally active in causing the release of lysosomal enzymes from human neutrophile, and did not cause arachidonic acid release from macrophage-like cells. These results were in accord with our epidemiological study, in which very low prevalences of nonspecific respiratory disease were demonstrated even at the area with highest ash exposure.
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