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Exposure to pollen has been associated with an increased risk of respiratory symptoms in both allergic and nonallergic individuals. However, the association of pollen exposure with respiratory symptoms during infancy, a particularly vulnerable period for lung development, remains unclear. The goal of this study was to examine whether pollen exposure is associated with respiratory symptoms (cough, wheezing, and dyspnoea) during the first year of life and to test if maternal atopy, infant’s sex, and air pollution modify this association.

Verfrühter Fruchtabwurf in Schweizer Buchenbeständen im Hitze- und Trockensommer 2018 Die Rotbuche (Fagus sylvatica) zeigt mit ihrer Fortpflanzungsstrategie ein klares Mastverhalten, das heisst, sie produziert nur in einzelnen Jahren sehr grosse Mengen an Blüten und Früchten (Bucheckern). Bisher wurde angenommen, dass die Buche zu den Baumarten gehört, die bei erfolgter Bestäubung in aller Regel auch Früchte produziert. Im Schweizer Hitze- und Trockensommer 2018 reagierte die Buchen an einigen Standorten aber anders: Nach einer sehr starken Blüte entwickelten sie nur wenige Früchte, oder sie warfen die unvollständig entwickelten Früchte bereits Mitte des Sommers ab. Die Analyse von Messdaten der letzten 15 bis 19 Jahre von drei Buchenuntersuchungsflächen der Langfristigen Waldökosystem-Forschung (LWF) zeigt, dass starke Hitzewellen und langanhaltende Trockenheit während der Fruchtentwicklung zu einem Abbruch der Fruchtproduktion führen können. Diese extremen Wetterverhältnisse funktionieren somit als «Umweltveto». In Jahren mit vergleichbaren Bedingungen während der Fruchtentwicklung waren die Durchschnittstemperaturen im Sommer um 1.5 °C höher, und der Niederschlag war um 45% niedriger als im langjährigen Mittel. Der angenommene Zweijahreszyklus der Buchenblüte kann somit nicht nur durch ungünstige Wetterbedingungen während der Bestäubung, sondern auch während der Fruchtentwicklung unterbrochen werden.

Pollen monitoring has traditionally been carried out using manual methods first developed in the early 1950s. Although this technique has been recently standardised, it suffers from several drawbacks, notably data usually only being available with a delay of 3–9 days and usually delivered at a daily resolution. Several automatic instruments have come on to the market over the past few years, with more new devices also under development. This paper provides a comprehensive overview of all available and developing automatic instruments, how they measure, how they identify airborne pollen, what impacts measurement quality, as well as what potential there is for further advancement in the field of bioaerosol monitoring.

This study presents the results of a Europe-wide training and Quality Control (QC) exercise carried out within the framework of the European Aerobiology Society’s QC Working Group. The main aim of this exercise was to examine the feasibility of carrying out a QC exercise for fungal spore monitoring in Europe, using a similar methodology to the one previously used for pollen. The QC survey was conducted in two parts: (1) Coordinators of national and regional aerobiological networks in Europe involved in the monitoring of atmospheric fungal spores were invited to complete a questionnaire survey related to their network and asked whether they were interested in taking part in an external inter-laboratory QC exercise; (2) Participating networks performed an inter-laboratory ring test with the same sample slide in order to determine the reproducibility of identifying and counting two fungal spore taxa (Alternaria and Epicoccum) in air samples collected by a Hirst-type volumetric spore trap. Participants were instructed to read five separate longitudinal transects in the “effective collecting area” of the slide. Reproducibility of analysis was determined following the method previously used in the European Aerobiology Society’s QC exercises for pollen. Thirty-two counters from 16 national or regional networks in Europe participated in the QC exercise. Coefficients of Variation (CV%) ranged from 23.0 to 22.5 when reading one transect and from 14.0 to 16.0 when reading five transects for Alternaria and Epicoccum, respectively. Considering a CV% of 30 as the limit for fungal spores, no significant differences were observed between the absolute errors from two, three, four and five transects. The only significant difference was between one and five transects. We recommend that fungal spore analysis should be carried out on about 5% of the slide (two transects in this study) because results were not significantly different to five transects.

A paper published in Global Change Biology in 2006 revealed that phenological responses in 1971-2000 matched the warming pattern in Europe, but a lack of chilling and adaptation in farming may have reversed these findings. Therefore, for 1951-2018 in a corresponding data set, we determined changes as linear trends and analysed their variation by plant traits/groups, across season and time as well as their attribution to warming following IPCC methodology. Although spring and summer phases in wild plants advanced less (maximum advances in 1978-2007), more (~90%) and more significant (~60%) negative trends were present, being stronger in early spring, at higher elevations, but smaller for nonwoody insect-pollinated species. These trends were strongly attributable to winter and spring warming. Findings for crop spring phases were similar, but were less pronounced. There were clearer and attributable signs for a delayed senescence in response to winter and spring warming. These changes resulted in a longer growing season, but a constant generative period in wild plants and a shortened one in agricultural crops. Phenology determined by farmers' decisions differed noticeably from the purely climatic driven phases with smaller percentages of advancing (~75%) trends, but farmers' spring activities were the only group with reinforced advancement, suggesting adaptation. Trends in farmers' spring and summer activities were very likely/likely associated with the warming pattern. In contrast, the advance in autumn farming phases was significantly associated with below average summer warming. Thus, under ongoing climate change with decreased chilling the advancing phenology in spring and summer is still attributable to warming; even the farmers' activities in these seasons mirror, to a lesser extent, the warming. Our findings point to adaptation to climate change in agriculture and reveal diverse implications for terrestrial ecosystems; the strong attribution supports the necessary mediation of warming impacts to the general public.

The national pollen network of Switzerland was developed historically. Its 14 pollen traps were placed without considering their representativeness and spatial coverage. The plan for automation of the network gives the motivation for reviewing the network design and to determine the importance and representativeness of each existing monitoring station. Similarities and dissimilarities of the 20-year-long pollen data series (1997–2016) were studied by cluster analysis. Focus was put on the daily course of the pollen season of the seven most important allergenic pollen taxa. The cluster analysis based on correlations of daily pollen concentrations revealed a group of seven similar stations on the Swiss Plateau which differ clearly from the seven stations outside this region. The stations on the Swiss Plateau can be clustered into two subregions, a western and an eastern one. Their correlation coefficients are linearly correlated with distance (from 50 to 300 km). The pattern of the clusters is in good agreement with the division of Switzerland in bioclimatic regions.

Hirst-type volumetric spore traps are used across the globe and are the current standard instrument for monitoring pollen. While they suffer from various issues related to sampling, measurement, and human error, they are, nevertheless, relatively cost-efficient and robust instruments that have been in use for decades. They are also the only reference against which newer instruments can be directly evaluated and it is thus important to understand and quantify all errors to make fair comparisons. Here, we investigate the variability across three Hirst-type traps run in parallel for three months during the main pollen season in Payerne, Switzerland. A variety of temporal resolutions is studied. Overall, daily average values show median relative differences of 16% for total pollen (inter-quartile range (IQR) = 8–32%) and between 23 and 67% for the top three taxa considered. The values are identical for total pollen when only concentrations > 10 pollen grains/m3 are considered, but decrease notably for the individual taxa investigated, with median relative differences ranging 14–30%. At the 2-hourly resolution, there is considerably more variability between the three samplers, with median relative differences of 42% for total pollen (IQR = 20–88%) and 62–120% for the top three taxa, respectively. Again, when the lowest concentrations are not included, these differences decrease somewhat to 40% for total pollen (IQR = 19–78%) and 41–56% for the top three taxa, respectively. Observations of low concentrations below 10 pollen grains/m3 therefore have a large impact on the measurement uncertainty: for daily average total pollen concentrations there are differences of over 100% between the three samplers, and for individual taxa differences reach up to 200%, the maximum value possible in terms of pairwise comparisons.

Longitudinal shifts in pollen onset, duration, and intensity are public health concerns for the growing number of individuals with pollen sensitization. National analyses of long-term pollen changes are influenced by how a plant's main pollen season (MPS) is defined. Prior Swiss studies have inconsistently applied MPS definitions, leading to heterogeneous conclusions regarding the magnitude, directionality, and significance of multi-decade pollen trends. We examined national pollen data in Switzerland between 1990 and 2020, applying six MPS definitions (2 percentage-based and 4 threshold-based) to twelve relevant allergenic plants. We analyzed changes in pollen season using both linear regression and locally estimated scatterplot smoothing (LOESS). For 4 of the 12 plant species, there is unanimity between definitions regarding earlier onset of pollen season (p < 0.05), with magnitude of 31-year change dependent on specific MPS definition (hazel: 9–18 days; oak: 5–13 days; grasses: 8–25 days; and nettle/hemp: 6–25 days). There is also consensus (p < 0.05) for modified MPS duration among hazel (21–104% longer), nettle/hemp (8–52% longer), and ash (18–38% shorter). Between-definition agreement is highest for MPS intensity analysis, with consensus for significant increases in seasonal pollen quantity (p < 0.05) among hazel, birch, oak, beech, and nettle/hemp. The largest relative intensification is noted for hazel (110–146%) and beech (162–237%). LOESS analysis indicates that these multi-decade pollen changes are typically nonlinear. The robustness of MPS definitions is highly dependent on annual pollen accumulation, with definition choice particularly influential for long-term analysis of low-pollen plants such as ragweed. We identify systematic differences between MPS definitions and suggest future aerobiologic studies apply multiple definitions to minimize bias. In summary, national pollen onset, duration, and intensity have shifted for some plants in Switzerland, with MPS definition choice affecting magnitude and significance of these variations. Future public health research can determine whether these temporal and quantitative pollen changes correlate with longitudinal differences in population pollen sensitization., Graphical abstract Unlabelled Image, Highlights • We analyzed 3 decades of Swiss data for 12 plants using 6 pollen season definitions. • Over 1990–2020, pollen seasons began earlier for hazel, oak, grasses and nettle/hemp. • Pollen accumulation intensified for hazel, birch, oak, beech and nettle/hemp. • Pollen season definition impacts magnitude, direction, and significance of trends. • Climate change is impacting public health through changes in pollen release.

Background: 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. Methods: A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen exposure in the context of defining relevant time intervals for evaluation of efficacy in AIT trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered to achieve a consensus. Results: The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for “pollen season”, “high pollen season” (or “peak pollen period”) and “high pollen days”. Conclusion: This EAACI position paper provides definitions of pollen exposures for different pollen types for use in AIT trials. Their validity as standards remains to be tested in future studies.

Pollen calendars are one of the most comprehensible means to inform allergy sufferers or medical professionals about the mean presence of allergenic pollen during the course of the year. They have been produced with a variety of methods and were distributed with great success since the beginning of pollen monitoring. Current technologies, longer data series and changing user demands allow to develop new calculation methods. For designing the new pollen calendars of Switzerland, the following requirements were formulated: The pollen load levels in the calendars should correspond to the levels used in pollen forecasts. A pollen load level in the calendar should show the time window in which it potentially occurs. Further requirements were an automatic generation of the calendars, a regular update and the possibility to provide calendars for single stations, regions or specific pollen species. The data analysis is based on mean daily pollen concentrations of the last 20 years of all 14 pollen-monitoring stations in Switzerland for the 15 pollen types most relevant for allergies. For each day of the year, the 90% quantile of the daily pollen concentrations is determined in a moving 9-day time window over 20 years of data. The calculated concentrations are converted afterward into a pollen load level. The new method is flexible because various parameters can be selected freely: the reference period, the size of the moving time window, the quantile value and the thresholds for pollen load levels. Adjusting these parameters, also pollen calendars for fewer than 20 years can be calculated. However, a sensitivity analysis showed that a reference period of 20 years provides much more stable pollen calendars than shorter reference periods.

European beech is known to be a masting species, i.e. fruit production does not occur every year. It is thought to be a species which is flowering controlled, i.e. that after successful pollination, fruits and seeds would be produced. In the last two decades, years with high fruit production occurred every two to three years in Middle Europe, which may be indication for an inherent biennial cycle. However, successful fruit production can be hampered by disadvantageous weather conditions, such as frost events, during the pollination season.In Switzerland, after high beech pollen concentration was measured in spring of 2018, high fruit production was expected. However, during the extremely hot and dry European summer of 2018, beech produced no, or only small amounts of beechnuts in two of three long-term monitoring beech stands in Switzerland, which are part of the Swiss Long-Term Forest Ecosystem Research Programme. We observed that beechnuts were aborted in early summer already. Over the last decades, we found similar examples of mast failure and fruit abortion in years with hot and dry summer conditions. These extreme conditions can thus act as an “environmental veto”, similar to frost events during flowering. In years with fruit abortion, summer mean temperatures were 1.2°C higher, and precipitation sums were 45% lower than the long-term average. Our findings are evidence for a biennial masting cycle in European beech, which can be interrupted by extreme weather conditions such as extreme summer heat and drought or frost during flowering.

During 1971-2000 phenological responses of wild species in spring and summer matched the warming pattern in Europe, whereas timing of farming activities as well as autumnal leaf colouring did not mirror climate change to the same extent (Menzel et al. GCB 2006). These findings were a backbone of the corresponding global attribution study of the IPCC AR4 (Rosenzweig et al. 2007, 2008). Two decades of warming later, however, new phenological findings suggest that especially a lack of chilling and / or increasing influence of photoperiod may have lowered the phenological temperature response and that adaptation in agricultural management is taking place. We therefore updated the GCB 2006 study by asking three questions: What drives the inherent variation of trends? Can we now detect a warming signal in “false” agricultural (i.e. those being directly or indirectly determined by farmers’ management) and autumn phases? Is there still an attributable warming signal in phenology?The complete phenological dataset of Germany, Austria and Switzerland (1951-2018, ~97.000 times series, corresponding to 96.3% of PEP725 data) was analysed. We determined linear trends, studied their variation by plant traits / phenogroups, across season and time, and followed IPCC methodology for attributing phenological changes to warming patterns.For spring and summer phases of wild plants we found more (significantly) advancing trends (~90% and ~60% sign.) which were stronger in early spring, at higher elevations, but smaller for non-woody insect-pollinated species. Although mean trend strength decreased, changes in spring were strongly attributable to warming in spring and winter. We had similar but less strong findings for agricultural crops in these seasons. In contrast only ~75% of phenological phases set by farmers’ decisions were advancing, however this was the only phenological group for which the mean advance increased, indicating adaptation. Equally trends in farming phases in spring and summer were attributable to warming in winter and summer, respectively. Leaf coloring and fall was now predominantly delayed (57%) which was attributable to winter and spring warming, too.Thus, this update of the GCB2006 study demonstrates that there is still a significant and attributable phenological change pattern in Europe, in which number of (significant) trends pointing into the direction of warming increased, but mean trend strength mostly decreased, probably due to a lack of chilling and smaller forcing trends. More attention should be paid to the inherent variability of trends with traits / species groups, season and time triggering divers (e.g. ecological) consequences of these phenological shifts. Still existing differences between the generative period of crops and wild species as well as between the farming season and the general growing season call for more research in this area.

Years with high fruit production, known as mast years, are the usual reproduction strategy of European beech. Harsh weather conditions such as frost during flowering can lead to pollination failure in spring. It has been assumed that mast is controlled by flowering, and that after successful pollination, high amounts of fruits and seeds would be produced. However, the extremely hot and dry European summer of 2018 showed that despite successful pollination, beechnuts did not develop or were only abundant in a few forest stands. An in-depth analysis of three forest sites of European beech from the Swiss Long-Term Forest Ecosystem Research Programme over the last 15–19 years revealed for the first time that extreme summer heat and drought can act as an “environmental veto”, leading to early fruit abortion. Within the forest stands in years with fruit abortion, summer mean temperatures were 1.5 °C higher and precipitation sums were 45% lower than the long-term average. Extreme summer heat and drought, together with frost during flowering, are therefore disrupting events of the assumed biennial fruiting cycle in European beech., Scientific Reports, 10 (1), ISSN:2045-2322

Phenological data have become increasingly important as indicators of long-term climate change. Consequently, long-term homogeneity of the records is an important aspect. In this paper, we apply a breakpoint detection algorithm to the phenological series from the Swiss Phenology Network (SPN). A combination of three statistical tests is applied and different constraints are tested with respect to the choice of reference series. Breakpoint detection is only possible for a fraction of the series due to the shortness of some series and the lack of suitable reference series. Spring phases are more likely to be suitable than fall phases because of their higher spatial correlation. Out of nearly 3000 phenological series with at least 20 data points, only about 5% were found to be significantly inhomogeneous, although a visual validation indicates that many mid-sized breakpoints remained undetected. The detected breakpoints were compared with metadata and more than half of them could be attributed to a change of observer.

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.

The Asian chestnut gall wasp (ACGW; Dryocosmus kuriphilus Yasumatsu, Hymenoptera, Cynipidae) is considered as one of the most dangerous pests of the genus Castanea. In southern Switzerland, repeated heavy ACGW attacks prevented chestnut trees from vegetating normally for years before the arrival and spread of the biological control agent Torymus sinensis (Kamijo, Hymenoptera, Torymidae). This resulted in a greatly reduced green biomass and flower production. In this paper, we analyze the impact of such an ecosystem alteration of the environment on the composition of produced honey. Six beekeepers were chosen from sites with different densities of chestnut trees, each of which providing series of honey samples from 2010 to 2016. We determined the chestnut component in the honeys via a combined chemical and sensory approach, and correlated the obtained results with the degree of yearly ACGW-induced crown damage and weather conditions during the period in question in the surrounding chestnut stands. The chestnut component in the analyzed honey sample series showed a strong correlation with the degree of ACGW-induced crown damage, whereas meteorological conditions of the corresponding year had a very marginal effect. Decreases in the chestnut component of the honey were statistically significant starting from a ACGW infestation level of 30%.

Alnus × spaethii is a hybrid alder with the parent species A. japonica and A. subcordata. It is known for both its tolerance for urban climate conditions and enhanced air pollution concentrations and hence often figures on recommended tree guidance lists in towns. At the MeteoSwiss pollen station of Buchs (Switzerland), unusual early peaks of alder pollen already in December or January have been observed in the last 8 years. These peaks occurred several days to weeks earlier than at any other Swiss pollen station. As pollen source, an alley of Alnus × spaethii trees, planted in 1995–2000, 800 m south of the pollen trap could be identified. Phenological observations during this period in Buchs confirmed these pollen observations and showed that the trees were fully flowering on December 30, 2009, December 28, 2010 and 2011 and December 24, 2012. Due to the presence of Alnus × spaethii a very early, longer and more intense alder pollen season was observed in Buchs. As recently shown, these alder pollen can be also of clinical relevance. Thus, newly introduced plant species seem to be able to become a relevant allergen within a short time.

Background The EC-funded EuroPrevall project examined the prevalence of food allergy across Europe. A well-established factor in the occurrence of food allergy is primary sensitization to pollen. Objective To analyse geographic and temporal variations in pollen exposure, allowing the investigation of how these variations influence the prevalence and incidence of food allergies across Europe. Methods Airborne pollen data for two decades (1990–2009) were obtained from 13 monitoring sites located as close as possible to the EuroPrevall survey centres. Start dates, intensity and duration of Betulaceae, Oleaceae, Poaceae and Asteraceae pollen seasons were examined. Mean, slope of the regression, probability level (P) and dominant taxa (%) were calculated. Trends were considered significant at P < 0.05. Results On a European scale, Betulaceae, in particular Betula, is the most dominant pollen exposure, two folds higher than to Poaceae, and greater than five folds higher than to Oleaceae and Asteraceae. Only in Reykjavik, Madrid and Derby was Poaceae the dominant pollen, as was Oleaceae in Thessaloniki. Weed pollen (Asteraceae) was never dominant, exposure accounted for >10% of total pollen exposure only in Siauliai (Artemisia) and Legnano (Ambrosia). Consistent trends towards changing intensity or duration of exposure were not observed, possibly with the exception of (not significant) decreased exposure to Artemisia and increased exposure to Ambrosia. Conclusions This is the first comprehensive study quantifying exposure to the major allergenic pollen families Betulaceae, Oleaceae, Poaceae and Asteraceae across Europe. These data can now be used for studies into patterns of sensitization and allergy to pollen and foods.

The start date of flowering of allergenic species is of great interest in the context of allergy. Such forecasts can help to plan the therapy and design the medical treatment. For this purpose, temperature sum models are usually employed. Designing temperature sum models requires the selection of different parameters such as the base temperature and the start date for the temperature sum. However, the optimal parameterization is often unknown and varies depending on location and species. The purpose of this study was to systematically test parameterizations of temperature sum models based on 12 Swiss pollen stations. The examined taxa include Corylus, Alnus, Fraxinus, Betula, and Poaceae. We tested the simple thermal model type (forcing-only model hereafter) which relies solely on forcing temperatures and the sequential model type that includes also chilling temperatures. The mean absolute error was used to assess the performance of the models. Our study shows that the sequential model could not achieve a discernible reduction of the (statistical) error compared to the forcing-only model for all taxa. The mean absolute error lies roughly between 2 and 4 days with the lowest values for Betula. The optimized parameterizations in combination with temperature forecast and the climatological mean were used during the 2012 pollen season to provide daily updated forecasts of the start of flowering for all five taxa. Improvements of the models could possibly be achieved by testing additional temperature parameters as well as other meteorological factors such as precipitation or irradiation. Identification of a process-oriented model with high statistical performance for all stations would facilitate the implementation in numerical pollen dispersion models.

The spring phenology of plants in temperate regions strongly responds to spring temperatures. Climate warming has caused substantial phenological advances in the past, but trends to be expected in the future are uncertain. A simple indicator is temperature sensitivity, the phenological advance statistically associated with a 1 °C warmer mean temperature during the ‘preseason’, defined as the most temperature-sensitive period preceding the phenological event. Recent analyses of phenological records have shown a decline in temperature sensitivity of leaf unfolding, but underlying mechanisms were not clear. Here we propose that climate warming can reduce temperature sensitivity simply by reducing the length of the preseason due to faster bud development during this time period, unless the entire preseason shifts forward so that its temperature does not change. We derive these predictions theoretically from the widely used ‘thermal time model’ for bud development and test them using data for 19 phenological events recorded in 1970–2012 at 108 stations spanning a 1600 m altitudinal range in Switzerland. We consider how temperature sensitivity, preseason start, preseason length and preseason temperature change (1) with altitude, (2) between the periods 1970–1987 and 1995–2012, which differed mainly in spring temperatures, and (3) between two non-consecutive sets of 18 years that differed mainly in winter temperatures. On average, temperature sensitivity increased with altitude (colder climate) and was reduced in years with warmer springs, but not in years with warmer winters. These trends also varied among species. Decreasing temperature sensitivity in warmer springs was associated with a limited forward shift of preseason start, higher temperatures during the preseason and reduced preseason length, but not with reduced winter chilling. Our results imply that declining temperature sensitivity can result directly from spring warming and does not necessarily indicate altered physiological responses or stronger constraints such as reduced winter chilling. This article is protected by copyright. All rights reserved.

Background Clinical efficacy of pollen allergen immunotherapy has been broadly documented in randomized controlled trials. The underlying clinical endpoints are analysed in seasonal time periods pre-defined on the basis of 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. Methods A Task Force of the Immunotherapy and Aerobiology and Pollution Interest Groups of the EAACI reviewed the literature on pollen-exposure in the context of defining relevant time intervals for evaluation of efficacy in allergen immunotherapy trials. Underlying principles in measuring pollen exposure and associated methodological problems and limitations were considered in order to achieve a consensus. Results The Task Force achieved a comprehensive position in defining pollen exposure times for different pollen types. Definitions are presented for ‘pollen season’, ‘high pollen season’ (or ‘Peak pollen period’) and ‘high pollen days’. Conclusion This EAACI position paper provides definitions of pollen exposures for different pollen types for use in Allergen Immunotherapy trials. Their validity as standards remains to be tested in future studies. This article is protected by copyright. All rights reserved.

The drivers of spatial variation in ragweed pollen concentrations, contributing to severe allergic rhinitis and asthma, are poorly quantified. We analysed the spatiotemporal variability in 16-year (1995–2010) annual total (66 stations) and annual total (2010) (162 stations) ragweed pollen counts and 8 independent variables (start, end and duration of the ragweed pollen season, maximum daily and calendar day of the maximum daily ragweed pollen counts, last frost day in spring, first frost day in fall and duration of the frost-free period) for Europe (16 years, 1995–2010) as a function of geographical coordinates. Then annual total pollen counts, annual daily peak pollen counts and date of this peak were regressed against frost-related variables, daily mean temperatures and daily precipitation amounts. To achieve this, we assembled the largest ragweed pollen data set to date for Europe. The dependence of the annual total ragweed pollen counts and the eight independent variables against geographical coordinates clearly distinguishes the three highly infected areas: the Pannonian Plain, Western Lombardy and the Rhone-Alpes region. All the eight variables are sensitive to longitude through its temperature dependence. They are also sensitive to altitude, due to the progressively colder climate with increasing altitude. Both annual total pollen counts and the maximum daily pollen counts depend on the start and the duration of the ragweed pollen season. However, no significant changes were detected in either the eight independent variables as a function of increasing latitude. This is probably due to a mixed climate induced by strong geomorphological inhomogeneities in Europe.

Tree masting is one of the most intensively studied ecological processes. It affects nutrient fluxes of trees, regeneration dynamics in forests, animal population densities, and ultimately influences ecosystem services. Despite a large volume of research focused on masting, its evolutionary ecology, spatial and temporal variability and environmental drivers are still matter of debate. Understanding the proximate and ultimate causes of masting at broad spatial and temporal scales will enable us to predict tree reproductive strategies and their response to changing environment. Here we provide broad spatial (distribution range-wide) and temporal (century) masting data for the two main masting tree species in Europe, European beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) H. Karst.). We collected masting data from a total of 359 sources through an extensive literature review and from unpublished surveys. The dataset has a total of 1747 series and 18348 yearly observations from 28 countries and covering a time span of years 1677-2016 and 1791-2016 for beech and spruce, respectively. For each record, the following information is available: identification code; species; year of observation; proxy of masting (flower, pollen, fruit, seed, dendrochronological reconstructions); statistical data type (ordinal, continuous); data value; unit of measurement (only in case of continuous data); geographical location (country, Nomenclature of Units for Territorial Statistics NUTS-1 level, municipality, coordinates); first and last record year and related length; type of data source (field survey, peer reviewed scientific literature, grey literature, personal observation); source identification code; date when data were added to the database; comments. To provide a ready-to-use masting index we harmonized ordinal data into five classes. Furthermore, we computed an additional field where continuous series with length >4 years where converted into a five classes ordinal index. To our knowledge, this is the most comprehensive published database on species-specific masting behaviour. It is useful to study spatial and temporal patterns of masting and its proximate and ultimate causes, to refine studies based on tree-ring chronologies, to understand dynamics of animal species and pests vectored by these animals affecting human health, and it may serve as calibration-validation data for dynamic forest models. This article is protected by copyright. All rights reserved.

Relationships between temporal variations in the North Atlantic Oscillation (NAO) and grass pollen counts at 13 sites in Europe, ranging from Cordoba in the south-west and Turku in the north-east, were studied in order to determine spatial differences in the amount of influence exerted by the NAO on the timing and magnitude of grass pollen seasons. There were a number of significant (P < 0.05) relationships between the NAO and start dates of the grass pollen season at the 13 pollen-monitoring sites. The strongest associations were generally recorded near to the Atlantic coast. Several significant correlations also existed between winter averages of the NAO and grass pollen season severity. Traditional methods for predicting the start or magnitude of grass pollen seasons have centred on the use of local meteorological observations, but this study has shown the importance of considering large-scale patterns of climate variability like the NAO.

Long-distance pollen transport can substantially raise local pollen levels, but their relative contribution has not yet been quantified temporally or spatially in ragweed infested regions. Using common ragweed (Ambrosia artemisiifolia) pollen accumulation at a ragweed infested area, Szeged, Hungary as a test case, this study attempted to: (1) identify, using cluster analysis, biogeographical regions that contribute to long-range transport of ragweed pollen to Szeged; (2) quantify the relative contribution of ragweed pollen from these regions; (3) determine the relative contribution of “local” and “transported” pollen for Szeged. Using the HYSPLIT model, three-dimensional backward trajectories were produced daily over a 5-year period, 2009–2013 for ragweed pollen accumulation at Szeged. A k-means clustering algorithm using the Mahalanobis distance was applied in order to develop trajectory types. Nine back-trajectory clusters were identified. Cluster 1 (direction: from the Channel area south of Great Britain) and cluster 5 (direction: from Northern Mediterranean) were found the most relevant potential long-distance sources for Ambrosia pollen transport to Szeged. Potential source contribution function (PSCF) and concentration weighted trajectory (CWT) values indicated additional potential source areas including the central and eastern part of France, the northern part of Italy and the Carpathian Basin. For Szeged on non-rainy days, medium-range transport is important, while on rainy days the two transport ranges have equal weights. Based on the Granger causality, annual pollen amount transported by the atmospheric circulation is 27.8% of the annual total pollen at Szeged. From this quantity, 7.5% is added to (due to transport), while 20.3% is subtracted from (e.g. because of wash-out by frontal rainfalls going towards Szeged) local sources.

Resume Cette etude se propose, dans la perspective du rechauffement climatique, d’etudier la relation entre la temperature et la date de debut de pollinisation (DDP) du bouleau, un arbre a pollen allergisant particulierement important pour les allergiques dans le nord-ouest de l’Europe. Elle a permis de faire des projections pour les prochaines annees afin d’estimer, en fonction de l’evolution prevue des temperatures du printemps, l’evolution de la DDP du bouleau. L’etude a porte sur dix sites europeens, Kevo et Turku (Finlande), Londres (Royaume-Uni), Paris et Lyon (France), Bruxelles (Belgique), Zurich (Suisse), Vienne (Autriche), Poznan et Cracovie (Pologne). La periode d’etude couvrait une duree de six a 28 ans selon le site. Les pollens ont ete recueillis quotidiennement a l’aide de capteurs volumetriques de type Hirst, et les donnees comparees aux temperatures mensuelles de janvier a mai au moyen de correlations et de regressions multiples. Les resultats ont montre qu’en dehors de Kevo ou la tendance va vers des printemps plus froids et des DDP plus tardives, dans les autres sites on constate un rechauffement printanier associe a des DDP plus precoce : cette tendance est tres nette a Turku, Zurich, Londres, Vienne et Bruxelles, moins marquee en France et absente en Pologne. Les resultats de ce travail devront conduire a une mise a jour des calendriers polliniques et des modeles de prediction de la DDP, dans les sites ou se dessine une tendance nette.

A record-breaking heat wave affected the European continent in summer 2003. In Switzerland, the temperature in June, July and August exceeded the 1961–1990 mean by about 5 °C. These extreme temperatures had significant effects on the pollen production and on the airborne pollen loads. Especially affected was the grass pollen season, which started 1–2 weeks earlier than in the mean. During May and the first part of June the grass pollen production and dispersion was favoured by the warm and dry weather and many days with high pollen concentrations were registered. First water deficiencies occurred in June so that the grasses ceased to grow. The grass pollen season ended 7–33 days earlier than normal. For many of our stations of the Swiss pollen network this had never occurred as early as in 2003. The other herbaceous plants were not affected as much as the grasses. We measured very high Chenopodium and Plantago pollen concentrations, about normal concentrations of Urtica and Rumex and slightly lower Artemisia pollen concentrations than normal. The summer 2003 was exceptional and its reoccurrence is at the moment statistically extremely unlikely. But models of climatologists show that in the future, climate variations will increase and that in the period 2071–2100 about every second summer could be as warm or warmer and as dry or dryer than 2003.

The synthesis of a series (1-5) of fullerene and Zn(II)-porphyrin amphiphiles with polar dibenzo[24]crown-8 headgroups is described. Their ability to form Langmuir monolayers at the air-water interface was investigated ina systematic study. The Langmuir films were characterized by their surface pressure versus molecular area isotherms, compression and expansion cycles, and Brewster-angle microscopy. Complexation of larger alkali metal cations (K + and Cs + ) by the polar headgroups leads to higher molecular area requirements and a better anchoring to the aqueous subphase. The monolayers of the porphyrin-(dibenzo[24]crown-8) conjugates were transferred as Langmuir-Blodgett films onto glass slides and the films characterized by UV-vis spectroscopy and grazing-incidence X-ray diffraction. Good evidence was obtained that the porphyrin-fullerene-crown ether triad 5 adopts a sandwich geometry in the LB films. In such an arrangement, the electron-attracting carbon sphere benefits from attractive interactions with the sandwiching electron-rich porphyrin and crown ether chromophores. The described films could have potential applications as functional materials in optical and electronic technology.

A shift in the timing of birch pollen seasons is important because it is well known to be a significant aeroallergen, especially in NW Europe where it is a notable cause of hay fever and pollen-related asthma. The research reported in this paper aims to investigate temporal patterns in the start dates of Betula (birch) pollen seasons at selected sites across Europe. In particular it investigates relationships between the changes in start dates and changes in spring temperatures over approximately the last 20 years. Daily birch pollen counts were used from Kevo, Turku, London, Brussels, Zurich and Vienna, for the core period from 1982 to 1999 and, in some cases, from 1970 to 2000. The sites represent a range of biogeographical situations from just within the Arctic Circle through to North West Maritime and Continental Europe. Pollen samples were taken with Hirst-type volumetric spore traps. Weather data were obtained from the sites nearest to the pollen traps. The timing of birch pollen seasons is known to depend mostly on a non-linear balance between the winter chilling required to break dormancy, and spring temperatures. Pollen start dates and monthly mean temperatures for January through to May were compiled to 5-year running means to examine trends. The start dates for the next 10 years were calculated from regression equations for each site, on the speculative basis that the current trends would continue. The analyses show regional contrasts. Kevo shows a marked trend towards cooler springs and later starts. If this continues the mean start date will become about 6 days later over the next 10 years. Turku exhibits cyclic patterns in start dates. A current trend towards earlier starts is expected to continue until 2007, followed by another fluctuation. London, Brussels, Zurich and Vienna show very similar patterns in the trends towards earlier start dates. If the trend continues the mean start dates at these sites will advance by about 6 days over the next 10 years. Following this work, amendments will be needed to pollen calendars and local predictive models. It will also be important to assess the implications of earlier seasons for allergy sufferers.

Representatives of two classes of hexakis-adducts of C60 were prepared by templated synthesis strategies. Compound 8 with a dipyridylmethano addend in a pseudo-octahedral addition pattern was obtained by DMA-templated addition (DMA=9,10-dimethylanthracene; Scheme 1) and served as the starting material for the first supramolecular fullerene dimer 2. Hexakis-adduct 12 also possesses a pseudo-octahedral addition pattern and was obtained by a sequence of tether-directed remote functionalization, tether removal, and regioselective bis-functionalization (Scheme 2). With its two diethynylmethano addends in trans-1 position, it is a precursor for fascinating new oligomers and polymers that feature C60 moieties as part of the polymeric backbone (Fig. 1). With the residual fullerene π-electron chromophore reduced to a `cubic cyclophane'-type sub-structure (Fig. 4), and for steric reasons, 8 and 12 no longer display electrophilic reactivity. As a representative of the second class of hexakis-adducts, (±)-1, which features six addends in a distinct helical array along an equatorial belt, was prepared by a route that involved two sequential tether-directed remote functionalization steps (Schemes 3 and 5). In compound (±)-1, π-electron conjugation between the two unsubstituted poles of the carbon sphere is maintained via two (E)-stilbene-like bridges (Fig. 4). As a result, (±)-1 features very different chemical reactivity and physical properties when compared to hexakis-adducts with a pseudo-octahedral addition pattern. Its reduction under cyclic voltammetric conditions is greatly facilitated (by 570 mV), and it readily undergoes additional, electronically favored Bingel additions at the two sterically well-accessible central polar 6-6 bonds under formation of heptakis- and octakis-adducts, (±)-30 and (±)-31, respectively (Scheme 6). The different extent of the residual π-electron delocalization in the fullerene sphere is also reflected in the optical properties of the two types of hexakis-adducts. Whereas 8 and 12 are bright-yellow (end-absorption around 450 nm), compound (±)-1 is shiny-red, with an end-absorption around 600 nm. This study once more demonstrates the power of templated functionalization strategies in fullerene chemistry, providing addition patterns that are not accessible by stepwise synthetic approaches.

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 Gutsch (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 andGutsch. 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.

Training, quality assurance (QA) and quality control (QC) play an important role in building competence in monitoring and research in aerobiology. The main goals of this paper were to: (a) formulate an updated Minimum Requirements Report for pollen monitoring; (b) carry out a pilot QC exercise of staff involved in pollen counting from various national networks in order to examine between analysts reproducibility and develop a methodology that can be used in future QC exercises. A questionnaire survey was sent to coordinators of participating pollen monitoring networks. In addition, a total of 45 technicians from 15 European countries participated in the pilot QC exercise. All technicians were instructed to analyse two slides containing the following pollen types: (a) Poaceae and Betula pollen grains in the north of Europe; (b) Poaceae and Olea pollen grains in the south of Europe. Minimum Recommendations were produced based on the results of the questionnaire survey, published literature, and the outcomes of a workshop. In the QC exercise, it was noticed that technicians who followed the Minimum Recommendations and examined at least 10 % of the slide tended to have better indicators of precision and accuracy than those technicians who did not follow the Minimum Recommendations. The proposed Minimum Recommendations will help to improve the quality of scientific work, particularly for those who are considering the setting up of new monitoring sites. The results of the pilot QC exercise will help to develop a methodology that can be used again in the future, thereby ensuring data quality.

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.In the modelling section the concepts of a variety of process-based phenological models are sketched. Process-based models appear to exhaust the noisy information contained in commonly available observational phenological and pollen data sets. Any additional parameterisations do not to improve model quality substantially. Observation-based models, like regression models, time series models and computational intelligence methods are also briefly described. Numerical pollen forecast systems are especially challenging. The question, which of the models, regression or process-based models is superior, cannot yet be answered.

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.

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.

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.

In preparation for picosecond pump-probe experiments at the SwissFEL X-ray laser facility, the feasibility of collectively initiating surface chemical reactions using energetic pulses of terahertz radiation is being tested. © Schweizerische Chemische Gesellschaft.

Representatives of two classes of hexakis-adducts of C60 were prepared by templated synthesis strategies. Compound 8 with a dipyridylmethano addend in a pseudo-octahedral addition pattern was obtained by DMA-templated addition (DMA=9,10-dimethylanthracene; Scheme 1) and served as the starting material for the first supramolecular fullerene dimer 2. Hexakis-adduct 12 also possesses a pseudo-octahedral addition pattern and was obtained by a sequence of tether-directed remote functionalization, tether removal, and regioselective bis-functionalization (Scheme 2). With its two diethynylmethano addends in trans-1 position, it is a precursor for fascinating new oligomers and polymers that feature C60 moieties as part of the polymeric backbone (Fig. 1). With the residual fullerene π-electron chromophore reduced to a `cubic cyclophane'-type sub-structure (Fig. 4), and for steric reasons, 8 and 12 no longer display electrophilic reactivity. As a representative of the second class of hexakis-adducts, (±)-1, which features six addends in a distinct helical array along an equatorial belt, was prepared by a route that involved two sequential tether-directed remote functionalization steps (Schemes 3 and 5). In compound (±)-1, π-electron conjugation between the two unsubstituted poles of the carbon sphere is maintained via two (E)-stilbene-like bridges (Fig. 4). As a result, (±)-1 features very different chemical reactivity and physical properties when compared to hexakis-adducts with a pseudo-octahedral addition pattern. Its reduction under cyclic voltammetric conditions is greatly facilitated (by 570 mV), and it readily undergoes additional, electronically favored Bingel additions at the two sterically well-accessible central polar 6-6 bonds under formation of heptakis- and octakis-adducts, (±)-30 and (±)-31, respectively (Scheme 6). The different extent of the residual π-electron delocalization in the fullerene sphere is also reflected in the optical properties of the two types of hexakis-adducts. Whereas 8 and 12 are bright-yellow (end-absorption around 450 nm), compound (±)-1 is shiny-red, with an end-absorption around 600 nm. This study once more demonstrates the power of templated functionalization strategies in fullerene chemistry, providing addition patterns that are not accessible by stepwise synthetic approaches.

Trajectories can be considered as a powerful tool to study transport of aerosols and tracer gases into the atmosphere. The TRAJEK Model (Fay et al. 1994) developed by the DWD (Deutscher Wetterdienst) is used twice daily by MeteoSwiss to compute hundreds of trajectories. Forward trajectories can be used to forecast the transport of nuclear or chemical pollutants in case of civil or military accidents. They are computed at various levels from locations corresponding to existing nuclear installations. Forecasters can use these results any time to predict direction and speed of nuclei transport in case of accidental releases.