Effects of SO2 on the Respiratory Systems of Child Miyakejima Residents Nearly 2 Years after Returning to the Island

Abstract

ISEE-0129 Background: Mt. Oyama on Miyakejima Island erupted in June 2000. All Miyake village citizens were forced to evacuate the island in September 2000, due to continuous eruptions and emissions of unsafe amounts of volcanic gas, mainly sulfur dioxide (SO2). Beginning in February 2005, residents returned to live in the island despite the fact that volcanic gas was still being emitted. Objective: To examine the changes in child citizens’ respiratory systems from February 2006 to November 2007. Methods: The study population was 142 child citizens who participated in health checkups in November 2007, including 27 SO2 hypersusceptive children who had a current or past history of asthma, obstructive lung function, current symptoms of whistling and wheezing, and/or deterioration of respiratory symptoms [KN11]. Respiratory effects were evaluated by a questionnaire for respiratory symptoms and spirometry. SO2 was monitored at 7 sampling points within inhabited areas, and the mean SO2 concentration from February 2006 to November 2007 was 0.027 ppm. The area was categorized into four areas by average SO2 concentration, namely, areas L, H-1, H-2, and H-3, where the SO2 level was 0.010, 0.025, 0.030, and 0.040 ppm, respectively. Results: Compared to children in area L, the frequency of ”irritation of the nose” was significantly increased in the children in areas H-2 and H-3. Average %FVC(%) and %FEV1(%) in hypersusceptive children reduced −4.85 and −8.57 in November 2007 compared to February 2006, though no reduction observed in normosusceptive children. Conclusion: SO2 exposure-related respiratory systems were observed in child Miyakejima citizens nearly 2 years after they returned to the island where volcanic gas containing SO2 continued to be emitted.