An epidemiological survey of pollenosis was carried out on 96 farmers engaged in a pear orchard in Toyama prefecture. All subjects were asked about the complaint of clinical manifestations from pollens and examined by the intradermal skin test with pollen extracts. Airborne pollens were collected in the pear orchard using a gravity sampler. The results are as follows. 1. Many pollen grains of annual bluegrass (Poa annua L.) and other grasses were observed in the atmosphere of the pear orchard throughout the late April to May. Almost all pollen grains of Japanese pear (Pyrus pyrifolia Nakai) were found in the late April, although a few of them were detected during May. 2. The prevalence rate of nasal symptoms and ocular symptom of the farmers was about 20%. The peak of incidence of nasal symptoms and ocular symptom was observed in April to June. During these months, artificial pollinations of Japanese pears are carried out and the annual bluegrass pollens were wafting in the air. 3. Positive skin reactions to Japanese pear pollens were observed in 5.4% of the farmers and positive skin reactions to annual bluegrass pollens in 31.5% of them. All the positive skin reactors to Japanese pear pollens also showed the positive skin reaction to annual bluegrass pollens. The positive reaction to annual bluegrass pollens was more common among the farmers who worked more than 11 years than those worked less than 10 years. 4. Nasal symptoms such as sneeze were more common among the positive skin reactors to annual bluegrass pollens compared with the negative skin reactors. The seasonal peak of nasal and ocular symptoms was observed only among the positive skin reactors. These results suggest that the pear farmers were exposed to the pollen grains of Japanese pear and annual bluegrass, and the pollen allergens sensitized them inducing nasal and/or ocular symptoms.
