Takao MARUYAMA†, Tsuyoshi OHIZUMI*, Yutaka TANEOKA, Naoki MINAMI††, Norio FUKUZAKI†††, Hitoshi MUKAI††††, Kentaro MURANO†††† and Minoru KUSAKABE†††††
Niigata Prefectural Research Laboratory for Health and Environment; Sowa, Niigata-shi 950-2144 Japan † Present address: Niigata Prefectural Joetsu Public Health Center; Kasugayama, Joetsu-shi 943-0807 Japan †† Present address: Niigata Prefectural Government, Fire Prevention and EmergencyManagement Division; Shinko-cho, Niigata-shi 950-8570 Japan ††† Present address: Acid Deposition and Oxidant Research Center; Sowa, Niigata-shi 950-2144 Japan †††† National Institute for Environmental Studies; Onogawa, Tsukuba-shi 305-0053 Japan ††††† Institute for Study of the Earth's Interior, Okayama University; Misasa, Tottori 682-0193 Japan