Background: Approximately 16.2% of the Japanese population suffers from pollinosis. One of the forms of management is self-care (preventive care), which can be categorized as ‘indoor’ and ‘outdoor’. Outdoor self-care is usually emphasized, but indoor self-care is also important. Considerable pollen is found in indoor dust and this is thought to be one of the factors that worsens pollinosis and enables it to persistent for a long time, even after the pollinating period has finished. Taking this into consideration, we investigated the dynamic state of indoor pollen.
Methods: Floating indoor house dust was collected in Petri dishes. The amount of pollen in the house dust samples collected was measured using an LCD laboratory highly sensitive Cry j1 assay kit.
Results: The results showed that, indoors, a lot of Japanese cedar pollen (JCP) was found on the floor (tatami mats, carpets), sofas and curtains. The number of JCP in living rooms peaked in April after the pollinating period and decreased gradually; however, JCP was still found indoors, even as late as the following February. Floating JCP in the house was one-tenth of the JCP levels on the floor. Floating JCP increased on days with low humidity. Air conditioning temporarily increased levels of floating JCP in houses with an air conditioner, but the level of floating JCP decreased rapidly compared with the level of that in houses without an air conditioner. Nasal signs and symptoms disappeared completely at a level of 30 floating pollen counts/day per Petri dish.
Conclusion: Considerable JCP was found floating indoors with house dust after a pollinating season.