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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 C ordoba, Spain, and Evora, 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 C ordoba (3.9 pg Ole e 1/pollen) than in Evora (0.8 pg Ole e 1/pollen, P = 0.004). Indeed, yearly olive pollen counts in C ordoba were 2.4 times higher than in Evora, but Ole e 1 concentrations were 7.6 times higher. When modeling the origin of the pollen, >40% of Ole e 1 exposure in Evora 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.

Exposure to allergens is pivotal in determining sensitization and allergic symptoms in individuals. Pollen grain counts in ambient air have traditionally been assessed to estimate airborne allergen exposure. However, the exact allergen content of ambient air is unknown. We therefore monitored atmospheric concentrations of birch pollen grains and the matched major birch pollen allergen Bet v 1 simultaneously across Europe within the EU-funded project HIALINE (Health Impacts of Airborne Allergen Information Network). Pollen count was assessed with Hirst type pollen traps at 10 I min(-1) at sites in France, United Kingdom, Germany, Italy and Finland. Allergen concentrations in ambient air were sampled at 800 I min(-1) with a Chemvol (R) high-volume cascade impactor equipped with stages PM > 10 mu m, 10 mu m > PM > 2.5 mu m, and in Germany also 2.5 mu m > PM > 0.12 mu m. The major birch pollen allergen Bet v 1 was determined with an allergen specific ELISA. Bet v 1 isoform patterns were analyzed by 2D-SDS-PAGE blots and mass spectrometric identification. Basophil activation was tested in an FC epsilon R1-humanized rat basophil cell line passively sensitized with serum of a birch pollen symptomatic patient. Compared to 10 previous years, 2009 was a representative birch pollen season for all stations. About 90% of the allergen was found in the PM > 10 mu m fraction at all stations. Bet v 1 isoforms pattern did not vary substantially neither during ripening of pollen nor between different geographical locations. The average European allergen release from birch pollen was 3.2 pg Bet v 1/pollen and did not vary much between the European countries. However, in all countries a >10-fold difference in daily allergen release per pollen was measured which could be explained by long-range transport of pollen with a deviating allergen release. Basophil activation by ambient air extracts correlated better with airborne allergen than with pollen concentration. Although Bet v 1 is a mixture of different isoforms, its fingerprint is constant across Europe. Bet v 1 was also exclusively linked to pollen. Pollen from different days varied >10-fold in allergen release. Thus exposure to allergen is inaccurately monitored by only monitoring birch pollen grains. Indeed, a humanized basophil activation test correlated much better with allergen concentrations in ambient air than with pollen count. Monitoring the allergens themselves together with pollen in ambient air might be an improvement in allergen exposure assessment. European Commission Christine Kühne - Center for Allergy Research and Education

These resulls show thal Ole e 1 is preferenlially associaled wilh pollen grains, allhough a small percenlage may also be found in submicronic particies. It was recorded a yeariy variation in airborne pollen and Ole e1. The highesl polency pollen and the highesl allergen index were recorded in 2010, a season wllh lhe lowesl pollen index. ln conclusion, aeroallergen quanlification may contribute togelher with airbome pollen counts, to a betler understanding 01 lhe exposure leveis lo airbome pollen allergens. Acknowledgments: This study is integraled in the European project HIALlNE (Executive Agency for Health and Consumers, grant agreemenl No 20081107)

ln general it has been observed similar profiles lor airborne pollen and aeroallergens content in the air, being aeroal/ergens more associated to XL Iraction stage. On the olher hand, ii has been delected al/ergenic activity out Irom pol/en season, especiaily in the case 01 M stage. Smaller particles are more exposed to medium-Iong distant transporto Moreover, results have provides strong evidence that similar value 01 airbome pol/en evokes different ambient air allergen loads in different geographicai areas. Even more, when lhe same area is considered the allergen load of the pol/en can vary within lhe season. Pollen differs in allergen release between European countries. Our sludy suoports lhe importance 01 lhe aeroal/ergen quantificatlon logether wilh airborne pol/en counls, in order to define the ouldoor air allergenic load. Conclusions: Under these results, the expected outcomes are lhe implementation 01 a network of European outdoor allergen measurements to belter predict allergic symploms. Also lhe climafic lactors that govem allergen exposure in ouldoor air will be eslablished. These can be used lo calculate the effect 01 climate change on lhe health effecls 01 airborne al/ergens. Pol/eninlo.org offers a new 1001 on Patient's Hayfever Diary (PHD).

The results in Italy should be compared with those from partners in other counlries. II will be important to confirm some observations during the first and second year of the projecl activity which showed the presence of a different allergenic power in difleren! geographical areas as observed for other types of pollen (Poaceae and Olea). The aim of lhe project was to measure the pollen's capacity to release allergens and this will result inlo an allergen exposure forecast, taking into consideration pollen counts and allergen release trom diflerent locations. The results of the project will help medical doctors, authorities and patients to better manage lhe diflerent aspects related to pollinosis.