Daily variations of Urticaceae pollen count and influence of meteoclimatic parameters in East Perugia during 1989

Summary Urticaceae pollen monitoring was carried out, in the atmosphere of East Perugia during the summer of 1989. In summer the Urticaceae pollen shows a fluctuating diurnal trend, which was analysed daily over six 4-hour periods. The high peaks of thistaxon were recorded in the middle of the day in July and August, and in the morning in June. The percentage pattern of the daily mean pollen concentration of Urticaceae was compared with mean temperature, wind speed, relative humidity and rain, both in the non-rainy days and rainy ones. The best correlations came out comparing pollen concentration and meteoclimatic parameters during non-rainy days. The interpretation of the influence of rainfalls is very difficult owing to their peculiar features in summer.