A retrospective study was performed in 113 patients with allergic rhinitis who visited the out-patient clinic in the Department of Otorhinolaryngology, Shuto General Hospital during 1 year from January to December 1988.
Although our hospital is located in a rural city where was pollution-free and good environmental area, many patients with allergic rhinitis visited us. High positive reactions of allergic skin tests were Japanese ceder, house dust, ragweed and orchard grass. About 60% of patients visited first in February, March and April when was the season of Japanese ceder pollen scattering. From the above, it was considered that most of patients with allergic rhinitis who visited our hospital are Japanese ceder pollinosis.

The atmospheric pollen counts of Ceder (Cryptomeria japonica) and Cypress (Chamaecypanis obtsusa) were measured with Durham's standard devices installed on the roofs and ground in Yanai city, Yamaguchi prefecture, during the period between 1984 and 1987, and the following results were obtained.
1) The number of atmosphreic pollen counts changed significantly every year. There was a large quantity of pollen counts recorded in 1984 and 1986, but a small quantity in 1985 and 1987. 2) Scattering period of atmospheric pollen counts also changed every year. In 1987 the atmospheric pollen began early in February. In 1985 and 1986, it began in late February and in 1984 in late March.
3) The atmospheric pollen counts on the roofs were recorded 3 times as much as those on the ground. But there were no substantial difference between those on the roofs and ground concerning the scattering peroid of atmospheric pollen and the daily change of it's counts. There was observed significant correlation between those on the roofs and ground.(coeffecient of multiple correation=0.987)