Regula Gehrig

Changes to Airborne Pollen Counts across Europe

A progressive global increase in the burden of allergic diseases has affected the industrialized world over the last half century and has been reported in the literature. The clinical evidence reveals a general increase in both incidence and prevalence of respiratory diseases, such as allergic rhinitis (common hay fever) and asthma. Such phenomena may be related not only to air pollution and changes in lifestyle, but also to an actual increase in airborne quantities of allergenic pollen. Experimental enhancements of carbon dioxide (CO) have demonstrated changes in pollen amount and allergenicity, but this has rarely been shown in the wider environment. The present analysis of a continental-scale pollen data set reveals an increasing trend in the yearly amount of airborne pollen for many taxa in Europe, which is more pronounced in urban than semi-rural/rural areas. Climate change may contribute to these changes, however increased temperatures do not appear to be a major influencing factor. Instead, we suggest the anthropogenic rise of atmospheric CO levels may be influential.

Monitoring, Modelling and Forecasting of the Pollen Season

The section about monitoring covers the development of phenological networks, remote sensing of the season cycle of the vegetation, the emergence of the science of aerobiology and, more specifically, aeropalynology, pollen sampling instruments, pollen counting techniques, applications of aeropalynology in agriculture and the European Pollen Information System. Three data sources are directly related with aeropalynology: phenological observations, pollen counts and remote sensing of the vegetation activity. The main future challenge is the assimilation of these data streams into numerical pollen forecast systems. Over the last decades consistent monitoring efforts of various national networks have created a wealth of pollen concentration time series. These constitute a nearly untouched treasure, which is still to be exploited to investigate questions concerning pollen emission, transport and deposition. New monitoring methods allow measuring the allergen content in pollen. Results from research on the allergen content in pollen are expected to increase the quality of the operational pollen forecasts.

Airborne Pollen Transport

This chapter reviews the present knowledge and previous developments concerning the pollen transport in the atmosphere. Numerous studies are classified according to the spatial scales of the applications, key processes considered, and the methodology involved. Space-wise, local, regional and long-range scales are distinguished. An attempt of systematization is made towards the key processes responsible for the observed patterns: initial dispersion of pollen grains in the nearest vicinity of the sources at micro-scale, transport with the wind, mixing inside the atmospheric boundary layer and dry and wet removal at the regional scale, and the long-range dispersion with synoptic-scale wind, exchange between the boundary layer and free troposphere, roles of dry and wet removal, interactions with chemicals and solar radiation at the large scales.

Defining pollen exposure times for clinical trials of allergen immunotherapy for pollen‐induced rhinoconjunctivitis – an EAACI Position Paper

Clinical efficacy of pollen allergen immunotherapy (AIT) has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods predefined based on the background pollen concentration. However, any validated or generally accepted definition from academia or regulatory authorities for this relevant pollen exposure intensity or period of time (season) is currently not available. Therefore, this Task Force initiative of the European Academy of Allergy and Clinical Immunology (EAACI) aimed to propose definitions based on expert consensus.

Hay Fever as a Christmas Gift

Pollen allergies are considered uncommon in winter. After hybrid alders were planted along a boulevard in Switzerland, allergic symptoms developed in children in the winter. Serum IgE antibodies against alder implicated the hybrid tree as the culprit.

Recommended Terminology for Aerobiological Studies

Aerobiology is an interdisciplinary science where researchers with different backgrounds are involved in different topics related to microorganism, airborne biological particles, e.g. pollen and spores, and phenology. Some concepts, words or expressions used in aerobiology have a clear definition, but are however frequently misused. Therefore, the working group “Quality Control” of the European Aerobiology Society (EAS) and the International Association of Aerobiology (IAA) would like to clarify some of them, their use and presentation.

Pollen distribution at elevations above 1000 m inSwitzerland

In Switzerland the concentration of allergenic pollendecreases with increasing elevation of the samplingsite of the Swiss pollen measuring network. The aim ofthis study was, to compare the pollen concentrationsof five different localities in the Swiss Alps and inthe Jura mountains, to get an idea of the differencesin the pollen abundance in altitudes above 1000 m. Theinvestigated localities are: La Chaux-de-Fonds(1040 m), Wiesen (1420 m), Davos (1600 m), Samedan(1705 m) and Gütsch (2287 m). These pollen sumswere compared to the Swiss plateau (Basel 273 m).Basel, La Chaux-de-Fonds and Wiesen show clearlyhigher pollen values than Davos, Samedan andGütsch. Pollen concentrations of Corylus,Alnus glutinosa-type and Fraxinus arereduced with increasing altitude and are only a smallproblem for allergies above 1000 m. Betulapollen are also reduced in the higher localities, butthere still occur many days with high pollenconcentrations. Especially Betula pollen frommedium range transport can play an important role forallergies in higher localities. The total grass pollensum does not decrease up to an altitude of 1500 m. Thegrass pollen concentration depends more on factorslike composition of the local grassland, land use andwind situation.Pollen concentrations at higher elevations isinfluenced by the local vegetation, a reduced pollenproduction, land use, topography, exposition, windvelocity and wind direction. These factors modify thepollen concentration considerably. Due to the complextopography of the Prealps and Alps, it is thereforenot possible to propose a general rule of pollenreduction with increasing altitude.

Climate Change and Evolution of the Pollen Content of the Air in Seven European Countries: the Example of Birch

The aim of this paper is to study the relation between climate change and the earliness of Birch pollination, a tree that produces allergenic pollen, which is of particular importance in north-western Europe. The study allowed us to make projections for the next few years in order to evaluate the evolution of Birch pollination starting date according to spring temperatures. It has been done in ten European locations, Kevo and Turku (Finland), London (United Kingdom), Paris and Lyon (France), Brussels (Belgium), Zurich (Switzerland), Vienna (Austria), Poznan and Cracow (Poland). The study period ranged from six to twenty-eight years depending on the city. Pollens were recorded daily thanks to volumetric Hirst traps, and the data were compared to monthly temperatures from January to May using correlations and multiple regressions. Except in Kevo where the trend is towards colder springs and a later pollination, in the other cities the results showed a spring warming associated with an earlier starting date of pollination: this trend is very well marked in Turku, Zurich, London, Vienna and Brussels, less evident in France while there is no trend in Poland. The results of this work should lead to an updating of the pollen calendars and the pollen forecast models, in the cities where there is a pronounced trend.

On the efficiency and correction of vertically oriented blunt bioaerosol samplers in moving air

The aspiration efficiency of vertical and wind-oriented Air-O-Cell samplers was investigated in a field study using the pollen of hazel, sweet chestnut and birch. Collected pollen numbers were compared to measurements of a Hirst-type Burkard spore trap. The discrepancy between pollen counts is substantial in the case of vertical orientation. The results indicate a strong influence of wind velocity and inlet orientation relative to the freestream on the aspiration efficiency. Various studies reported on inertial effects on aerosol motion as function of wind velocity. The measurements were compared to a physically based model for the limited case of vertical blunt samplers. Additionally, a simple linear model based on pollen counts and wind velocity was developed. Both correction models notably reduce the error of vertically oriented samplers, whereas only the physically based model can be used on independent datasets. The study also addressed the precision error of the instruments used, which was substantial for both sampler types.

Alder pollen of Alnus spaethii at christmas: from epidemiology of molecular allergens to the political solution

Methods IgE antibodies to 103 molecular allergens were measured (using ImmunoCAP ISAC) in serum samples obtained from 54 students in 1986 and from 46 students in 2006. In 2010, 12 of the former students from 1986 with positive IgE antibodies to inhalant allergens where retested. Along the main boulevard in Buchs 96 hybrid trees (Alnus spaethii) were planted 1995-2000. Atmospheric pollen levels were measured in Buchs since 1984, phenological observation since 2009.