Pollen is routinely monitored, but it is unknown whether pollen counts represent allergen exposure. We therefore simultaneously determined olive pollen and Ole e 1 in ambient air in Córdoba, Spain, and Évora, Portugal, using Hirst‐type traps for pollen and high‐volume cascade impactors for allergen. Pollen from different days released 12‐fold different amounts of Ole e 1 per pollen (both locations P < 0.001). Average allergen release from pollen (pollen potency) was much higher in Córdoba (3.9 pg Ole e 1/pollen) than in Évora (0.8 pg Ole e 1/pollen, P = 0.004). Indeed, yearly olive pollen counts in Córdoba were 2.4 times higher than in Évora, but Ole e 1 concentrations were 7.6 times higher. When modeling the origin of the pollen, >40% of Ole e 1 exposure in Évora was explained by high‐potency pollen originating from the south of Spain. Thus, olive pollen can vary substantially in allergen release, even though they are morphologically identical.

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This study aims to determine the potential origin of Olea pollen recorded in Badajoz in the Southwest of the Iberian Peninsula during 2009-2011. This was achieved using a combination of daily average and diurnal (hourly) airborne Olea pollen counts recorded at Badajoz (southwestern Spain) and Évora (southeastern Portugal), an inventory of olive groves in the studied area and air mass trajectory calculations computed using the HYSPLIT model. Examining olive pollen episodes at Badajoz that had distinctly different diurnal cycles in olive pollen in relation to the mean, allowed us to identify three different scenarios where olive pollen can be transported to the city from either distant or nearby sources. Back trajectory analysis showed that olive pollen can be transported to Badajoz from the West on prevailing winds, either directly or on slow moving air masses, and from high densities of olive groves situated to the Southeast (e.g. Andalucía). Regional scale transport of olive pollen can result in increased nighttime concentrations of this important aeroallergen. This could be particularly important in Mediterranean countries where people can be outdoors during this time due to climate and lifestyle. Such studies are valuable for allergy sufferers and health care professionals because the information can be incorporated into forecasts, the outputs of which are used for avoiding exposure to aeroallergens and planning medication. The results of studies of this nature can also be used for examining gene flow in this important agricultural crop.

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The Coriolis d air sampler is a new volumetric air sampler, dedicated to outdoor monitoring of airborne biological particles, including pollen and spores. In the present work, the performance of the Coriolis in the collection of pollen grains was evaluated in comparison with a Hirst spore trap, the most frequently used trap in aerobiological studies, in two cities of South Europe, Evora (Portugal) and Córdoba (Spain). Both concentration values are compared, and statistical analysis was carried out. The present study indicated that, in general, pollen counts for all taxa detected with the Hirst trap were higher than those detected with the Coriolis d in both cities. In Córdoba, significant differences were detected for all taxa except for Cupressus, Olea and Pinus, while in Evora significant differences were noted for all except Pinus and Poaceae. Differences were particularly marked in species flowering during April and May. In spite of theses differences, Spearman correlation test results showed that the relationship between Hirst and Coriolis curves was always positive and significant (p [ 0.01). Regards to the number of detected taxa, the results showed greater diversity for the Hirst sampler in both cities.