A 10-year aerobiological study (1994-2003) in the Mediterranean island of Crete, Greece: grasses and other weeds, aerobiological data, and botanical and clinical correlations.

Grasses and weeds contain species that produce abundant pollen grains and have been implicated as causative agents in both asthma and allergic rhinitis. In this study, we present the pollen counts of allergenic grasses and weeds on the island of Crete and show their impact on allergic individuals. Heraklion is located at the center of the north shore of Crete and has been monitored with a Burkard 7-day volumetric spore trap since 1994, to determine the identity, concentration, and seasonal variation of airborne pollen grains. Data from 10 consecutive years were recorded, analyzed, and correlated to the growth of respective plants on this island. The island's vegetation and blossoming periods have been investigated by conducting field trips. In parallel, an atopic population of 576 individuals with a convincing history of allergic respiratory disease-rhinitis and/or asthma-was subjected to skin-prick tests with 50 common allergens. Quantitatively, there was a fair agreement between total pollen counts and positive skin-prick test frequencies for Parietaria (Urticaceae family). For the majority of the grass and weed genera, strongly positive skin test responses were observed frequently, despite rather low pollen counts.