A statistic study of atmospheric pollen in Japan.

By using a volumetric method, the authors made an investigation on airborne pollen grains in connection with the incidence of pollinosis since 1969, in Toho University, Funabashi, Chiba, Japan. The airborne pollen grains in each sample were counted under the microscope to identify the pollen types, and the pollen grains were classified into seven types according to the classification of pollen grains in Japan reported by Ikuse. In this report, the accumulated number of each species was analyzed statistically by circular plot, semi-logarithmic plot and test of skewness (g1) and kurtosis (g2) of frequency distribution by G. W. Snedecor. From the investigation in the years of 1969, 1970, 1990, 1991, the most frequent airborne pollen grains belonged to the 1-aperturate 3C(ab) type pollen in 1969 and 1970, and to the 1-aperturate 3B type pollen in 1990 and 1991, reflecting the change of environment during twenty years. By the g1 and g2 statistics for almost all species, the mode of distribution curve was significantly smaller than the mean, indicating that the whole distribution significantly skewed from a normal distribution, and the peak was flat for the herbs, while sharp for the trees.