If you experience itchy eyes, a runny nose, and more sneezing or coughing than normal, you’re probably familiar with allergic rhinitis. When allergic rhinitis is triggered by pollen, it is referred to as “hayfever” or “pollinosis.” Allergenic pollens differ regionally and many people around the world are impacted by pollinosis.
Researchers from Tokyo University of Agriculture and Technology (TUAT) state that 17% of the Japanese population, about 20 million people, suffer from seasonal hayfever during the spring and summer. The main allergen comes from Japanese cedar pollen; also called “sugi,” this is the largest tree species in Japan. The second-largest tree species, and second in allergenic pollen production, is the Japanese cypress (hinoki). These two species cover a combined 7 million hectares. They release pollen from February to May, which can cause symptoms from itchy eyes to severe respiratory disorders.
Predicting pollen abundance and spatial distribution can aid pollinosis sufferers and doctors treating the condition. The TUAT research team studied annual patterns of airborne allergic pollen throughout the country. Most available information about pollen distribution was held to the local level. The results of this study, the first of its kind, were published earlier this month in Scientific Reports.
The team used public data from the Japanese Ministry of the Environment’s “Hanako-san” pollen observation system. Prior research has shown allergenic pollen distribution has an alternating “on/off” cycle, but it differs regionally. The team aimed to investigate annual fluctuations and spatial synchronization in pollen distribution at the national level using data from 120 locations over five years.
Their results showed than synchronization was strong in eastern Japan and weak in western Japan. They also discovered that at the national level, synchronization was intermittent. In 2009-2010, all 120 sites were synchronized over 1600 kilometers. In 2015-2016, they were nearly perfectly desynchronized. In a news article from TUAT regarding the study, lead author Akira Ishibashi stated, "We still don't know what causes these regional differences in the pollen dispersal behavior. It could be related to correlations in environmental variabilities at the locations of the different tree populations, known as the Moran effect."
The researchers are hopeful that the information gained from this study will help individuals who suffer from pollinosis, as well as clinicians, prevent severe cases of the seasonal illness. These results may be used to create earlier predictions of national pollen distribution and abundance.