TY - JOUR T1 - From pollen count to pollen potency: the molecular era of aerobiology JF - European Respiratory Journal JO - Eur Respir J SP - 898 LP - 900 DO - 10.1183/09031936.00096413 VL - 42 IS - 4 AU - Lorenzo Cecchi Y1 - 2013/10/01 UR - http://erj.ersjournals.com/content/42/4/898.abstract N2 - In 1873, Charles Harrison Blackley recognised pollen as the cause of hay fever and “hay asthma” [1]. For the first time, he collected pollen grains with a kite that had a sticky tail and then he counted them. Being affected by seasonal asthma himself, he also performed the first skin prick test on his own arm. Since then, aerobiology (from Greek άήρ, aēr, “air”; βίiος, bios, “life”; and -λογίíα, -logia), a branch of biology that studies airborne organic particles, including pollen grains and fungal spores, has played a key role in the study of the relationship between allergic diseases and pollen. Although thousands of experimental studies have supported the role of pollen in the pathogenesis of allergic rhinitis, asthma and conjunctivitis, data from epidemiological studies were controversial in many cases, casting doubt on the pollen count (i.e. the number of pollen of the same type per cubic metre of air) as a reliable proxy of allergen exposure.Several reasons can be claimed for the inconsistency of these results. One is that effects of pollen cannot be considered the same for all species. The mix of allergenic pollen to which the allergic population is exposed varies dramatically both qualitatively (types of pollen) and quantitatively (amount of pollen), according to the characteristics of the local flora. Diversity of exposure profile accounts for the impossibility of finding a “universal” concentration of pollen that is able to induce symptoms, i.e. the clinical threshold, as is possible in the case of urban pollutants, for which limits are established at a European level. In fact, the clinical threshold of pollen varies in different geographical areas and among different pollen taxa, as extensively reviewed by De Weger et al. [2]. As a consequence, for instance, threshold values ranged between 4 and … ER -