Abstract

Abstract To determine the best date for patients to begin treatment for pollinosis, an attempt was made to predict the start of the grass pollen season as accurately as possible. A new method to define the start of the grass pollen season is presented. It identifies the date when at a certain location the accumulated total (from 1 Jan.) of 24 h average grass pollen concentrations (No./m3) reaches 100. This method is called the Σ100-method. Using the phenological method over the years 1977 through 1985, with the birch (Σ125=x) as the indicator plant, the start of the grass pollen period (Σ100=z) could be predicted more than twice as accurately as would have been possible solely based on the mean starting dates in the preceeding years. The predicted starting date (z) can be calculated with the equation z=0.68x+65.33 (x and z as day-of-the-year numbers), SD=1.6 day, r=0.86, n=9.