Association between Japanese cedar and cypress pollen counts and climate factors over a 10-year period in Tsu city, Japan

Abstract

Japanese cedar pollen and cypress pollen are the most common causes of seasonal allergic rhinitis in Japan. In the present study, we examined the relationship between climate factors and Japanese cedar and cypress pollen counts in Tsu city, Mie prefecture, Japan. Cedar and cypress pollen measurements were taken between 2009 and 2018 using a gravitational method (Durham’s sampler). Each year, during this 10-year period, measurements were taken daily from the beginning of February until the middle of May. The relationship between cedar and cypress pollen counts and the highest temperature, sunshine duration, and average humidity of a given year and the previous year were analyzed using multiple linear regression analysis. Sunshine duration in April of a given year and November of the previous year and average humidity in August of the previous year were associated with cedar and cypress pollen counts (R2 = 0.980, p < 0.000). Sunshine hours in April of a given year and temperature in August of the previous year were associated with cypress pollen counts; however, the temperature in October of the previous year was not (R2 = 0.872, p < 0.001). In addition, the temperature in January of a given year had an inverse association with cedar pollen counts (R2 = 0.338, p < 0.045). Thus, the evaluation of cedar and cypress pollen counts and weather conditions in Tsu city will provide valuable information to physicians for predicting pollen prevalence and treating patients with allergies effectively.