Allergy symptoms in relation to alder and birch pollen concentrations in Finland

In order to study allergic people responding to daily changes in pollen concentrations, we compared personal diary data on allergic symptoms and the use of allergy medicines to daily pollen counts during the two unequal alder and birch pollen seasons of 2009 and 2010. Almost 90% of the 61 subjects with physician-diagnosed birch pollinosis developed conjunctival, nasal or other symptoms during the peak birch pollination. Most subjects (95%) also reported symptoms during the alder pollination. Despite a delay between the most severe symptoms and the pollen peaks and the increased risk of allergy symptoms between the alder and birch pollen peaks at much lower pollen concentrations, the number of subjects with allergy symptoms correlated with the daily pollen concentrations in both years (r 09 = 0.35, r 10 = 0.36, p