[A relationship between the annual onset day of Japanese cedar pollinosis and pollen dispersion].

A statistical analysis of the annual day of onset of Japanese cedar pollinosis was carried out on a total of 305 patients seen at the out-patient clinic for allergic diseases in the Department of Otorhinolaryngology of Kyoto Prefectural University of Medicine between 1989 and 1991 (3 years). The day of onset varied among individuals and was distributed over a period of about one month, in patient number statistics, however, a clear single peak was seen for all 3 years. The day of onset in most patients showed tendency to peak after January 1, i.e., when the maximum temperature integral is approximately 450 degrees C, on warm days where the maximum temperature exceeds 15 degrees C, on days where there is little rain, and on days when there is a strong southerly wind. This peak onset day is about 3 weeks after first day of pollen count, or 3 or 4 days before the first dispersion peak, which corresponds to the day on which pollen dispersion begins in earnest. Furthermore, it was found that there was a drastic increase in the attack rate (from 10% to more than 50%) in pollinosis patients about 1 week before the peak day of onset. By the first dispersion peak, 70-80% of the patients had experienced an attack. The results of the present study may be useful in pollen forecasting and in treating early pollinosis in the dispersion season.