RESUMO
We have investigated the distribution of airborne pollen at the different eleven points in Japan from 1987 to 1998 using gravity sampler. To clarify the characteristics causative pollen for Japanese cedar pollinosis, we examined annual change of pollen counts, dispersing period and geographical difference of C. japonica and Cupressaceae pollen. C. japonica pollen occupied much more in Central Japan and Cupressaceae in the west of Japan than the other area. In Hamamatsu City, both of pollen counts were most of all and we found a tendency that the more pollen counts the longer dispersing period. As they reported that at the starting day of pollen in this method some patients had already suffered from allergic symptoms, we considered pollen grains were dispersing in spite of being continuously captured. In these twelve years we found that patients with Japanese pollinosis are exposured by causative agents during about 100 days every spring. But we could not observe the trend of increasing pollen counts and earlier starting day because of global warming. Further more we found that the pollen counts of C. japonica in autumn was increasing since 1994. As one of the factors of increasing patients with pollinosis, we thought that total exposure period of causative pollen every year were longer than that of 1980s.