Validation Study of the OHIO Chamber in Patients with Japanese Cedar Pollinosis

Background: An artificial exposure chamber (OHIO Chamber), which allows dispersal of a fixed concentration of Japanese cedar (JC) pollen under stable conditions, was constructed. This study was conducted to identify the exposure conditions assuring validity of the clinical tests conducted using this chamber. Methods: Twenty-four adult patients with JC pollinosis were exposed to different concentrations of JC pollen: 0 (only during the summer period), 4,000, 8,000 and 12,000 grains/m3, and the nasal and ocular symptoms were self-assessed during a 4-hour period of exposure. The amount of nasal discharge was measured and the sneezing frequency was recorded. This study was conducted twice during the summer and winter periods, i.e. non-pollen seasons. The reproducibility of the symptoms between the two seasons was assessed. Results: None of the subjects developed any symptom at the pollen concentration of 0 grains/m3. No significant differences in the time to the onset of symptoms were found between the summer and winter study, regardless of the pollen concentration. There were no significant differences between the summer and winter study in the total symptom score and total nasal symptom score at any pollen concentration, suggesting the very favorable reproducibility of symptoms. Conclusions: Efficient and reproducible results are obtained in patients exposed to JC pollen in the OHIO Chamber. The results suggest the conditions of JC pollen exposure have scientific validity and the OHIO Chamber has the potential to contribute significantly to basic and clinical studies of JC pollinosis.