Abstract
Variation of airborne benzo [α] pyrene (B [α] P) concentration in Niigata area were investigated in recent 10 years (April, 1981 to March, 1991) . Airborne dust was collected monthly on a glass fiber filter or a quartz fiber filter for 24 h with a high-volume air sampler at 14 investigated sites (St.1-14) in Niigata Prefecture. B [α] P was determined by the spectrofluorometric narrow base line method or a reversed phase high-performance liquid chromatography.
Geometric mean of B [α] P concentration at all sites was 0.25 ng·m-3 (0.12 to 0.49 ng·m-3) or 5.2 ng·mg-1 (2.8 to 11 ng·mg-1) . Annual mean concentration of B [α] P decreased in fiscal 1982 (from April to March), and was almost unchanged to fiscal 1987, but increased in fiscal 1988, and then decreased again in fiscal 1989 to fiscal 1990. The B [α] P concentration at the investigated site was affected by surrounding situation, i.e. factories, traffic and/or diesel enginery. B [α] P concentration was higher in winter season than in summer season. The soil dust which was transported from Asian continent by Kosa phenomenon, did not effect the B [α] P concentration significantly.
Mean of daily inhalation intake of B [α] P during the investigated period at all sites was estimated as 0.021-0.033 ng·d-1·g-1; mean of B [α] P cancer risk by inhalation was estimated as 0.83×10-6or 88×10-6, depending on the cancer unit risk factor adopted.
