Airborne Olea (olive) pollen in the Alentejo Region, Southern Portugal: agronomic, environmental and clinical implications

Abstract Background Olea (olive) is an economically important tree species, and its pollen allergens are the most common cause of pollen sensitization and allergic disease in Mediterranean Europe. This study aims to examine temporal variations in airborne Olea pollen in the Alentejo Region, Southern Portugal, and its agronomic, environmental and clinical implications. Method Daily average airborne Olea pollen concentrations, meteorological data and agronomic data from Alentejo (2001–2021) were used. Results The amount of airborne Olea pollen recorded annually increased significantly over the study period. There were also significant increases in peak values and duration of the Olea pollen season, as well as the number of days above the thresholds of 50, 100 and 200 Olea pollen grains /m 3 that are deemed sufficient to trigger symptoms of pollen allergy in susceptible individuals. Atmospheric concentrations of Olea pollen recorded in Évora have seen simultaneous increases in olive production, and statistically significant correlations (p < 0.001) exist between airborne Olea pollen levels and the quantity of olive fruit and olive oil produced in Alentejo during the period 2001–2021. Conclusion This is the first time that the phenology of olive trees, in the form of temporal changes in airborne pollen, has been related to the amount of olive fruit and olive oil produced in Alentejo in Portugal. The modernization of agricultural production systems and improvements to irrigation have led to increases in olive pollen, olive fruit and olive oil produced in the region. These changes are reflected in increased airborne concentrations of Olea pollen in Évora, and a subsequent increase in the allergenic risk to the sensitized population.