The olive tree, is widely spread in the Mediterranean Basin, particularly in those areas where the climate is generally warmer. Although the olive tree is economically important owing to the income it provides farmers, it can be considered a risk to human health because of the well-known allergenicity of olive pollen.
Olive anthesis occurs in some weeks from March to June and differences in its length and in the pollen amount during the years are reported in literature.
Daily pollen concentration is influenced by several tree factors (cultivar, age, technical practices) and by the meteorological daily trend.
In order to predict the time of the higher olive pollen concentration in the air, data of 10 pollen seasons (1984-1993) were recorded in an urban area of North Sardinia (Italy) with a Burkard seven-day recording volumetric spore trap. During the same period air temperature was recorded by standard weather station positioned near the spore trap. Temperature data were reported as degree-days calculated by the methods "daily averaging" and "single triangulation".
Degree-days were calculated using nine starting date and five base temperatures.
The lowest standard deviation in degree-days, in the coefficient of variation and in the standard deviation in days indicated in "single triangulation" as useful method to calculate degree-days and in 0°C the base temperature for Olive. This prediction was tested during the years 1995-1997 and a fitting of the peak within 2-3 days, in comparison of the observed peak of the higher pollen concentration, was found.