[Pollen surveys in Sapporo for 6 years during 1992 to 1997]

We carried out pollen surveys for 6 years from 1992 to 1997. The method of pollen survey studied was based on the standardization board of air born pollen survey and pollen information in Japan. The pollen samples were collected in Nishioka-area of Toyohira-ku, and Kawazoe-area of Minami-ku in Sapporo. As the pollen sample device. IS Rotary pollen trap was used at Nishioka-area during 1992 to 1994 and at Kawazoe-area in 1993, and Durham's pollen trap was used at Kawazoe-area during 1995 to 1997. The yearly pollen counts were highly fluctuated in trees, particularly Yew (Taxus spp.), Alder (Alnus spp.), Birch (Betula spp.), Pine (Pinus spp.), Fir (Abies spp.), than in Grasses (Gramineae) and Weeds (Polygonaceae, Plantago spp., Artemisia spp., Chenopodiaceae). In addition, the starting date of pollination was widely fluctuated year by year in trees. For instance, the pollen of Birch was confirmed on April 13 in 1993, as the first day in Nishioka-area, while it was on April 28 in 1994. It should be considered that the pollen counts and the starting date of pollination were highly dependent on the weather condition of the previous year and the current year.