Matt Smith

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.

The Long Range Transport of Birch (Betula) Pollen from Poland and Germany Causes Significant Pre-season Concentrations in Denmark

Background Birch pollen is highly allergic and has the potential for episodically long‐range transport. Such episodes will in general occur out of the main pollen season. During this time, allergy patients are unprotected and high pollen concentrations will therefore have a full allergenic impact.

Common ragweed: a threat to environmental health in Europe.

Common or short ragweed (Ambrosia artemisiifolia L.) is an annual herb belonging to the Asteraceae family that was described by Carl Linnaeus in the 18th century. It is a noxious invasive species that is an important weed in agriculture and a source of highly allergenic pollen. The importance placed on A. artemisiifolia is reflected by the number of international projects that have now been launched by the European Commission and the increasing number of publications being produced on this topic. This review paper examines existing knowledge about ragweed ecology, distribution and flowering phenology and the environmental health risk that this noxious plant poses in Europe. The paper also examines control measures used in the fight against it and state of the art methods for modelling atmospheric concentrations of this important aeroallergen. Common ragweed is an environmental health threat, not only in its native North America but also in many parts of the world where it has been introduced. In Europe, where the plant has now become naturalised and frequently forms part of the flora, the threat posed by ragweed has been identified and steps are being taken to reduce further geographical expansion and limit increases in population densities of the plant in order to protect the allergic population. This is particularly important when one considers possible range shifts, changes in flowering phenology and increases in the amount of pollen and allergenic potency that could be brought about by changes in climate.

Biological Flora of the British Isles: Ambrosia Artemisiifolia

This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history, conservation, impacts and management. Ambrosia artemisiifolia is a monoecious, wind-pollinated, annual herb native to North America whose height varies from 10 cm to 2.5 m, according to environmental conditions. It has erect, branched stems and pinnately lobed leaves. Spike-like racemes of male capitula composed of staminate (male) florets terminate the stems, while cyme-like clusters of pistillate (female) florets are arranged in groups in the axils of main and lateral stem leaves. Seeds require prolonged chilling to break dormancy. Following seedling emergence in spring, the rate of vegetative growth depends on temperature, but development occurs over a wide thermal range. In temperate European climates, male and female flowers are produced from summer to early autumn (July to October). Ambrosia artemisiifolia is sensitive to freezing. Late spring frosts kill seedlings and the first autumn frosts terminate the growing season. It has a preference for dry soils of intermediate to rich nutrient level. Ambrosia artemisiifolia was introduced into Europe with seed imports from North America in the 19th century. Since World War II, it has become widespread in temperate regions of Europe and is now abundant in open, disturbed habitats as a ruderal and agricultural weed. Recently, the North American ragweed leaf beetle (Ophraella communa) has been detected in southern Switzerland and northern Italy. This species appears to have the capacity to substantially reduce growth and seed production of A. artemisiifolia. In heavily infested regions of Europe, A. artemisiifolia causes substantial crop-yield losses and its copious, highly allergenic pollen creates considerable public health problems. There is a consensus among models that climate change will allow its northward and uphill spread in Europe.

Constructing a 7‐day ahead forecast model for grass pollen at north London, United Kingdom

Background A number of media outlets now issue medium‐range (∼7 day) weather forecasts on a regular basis. It is therefore logical that aerobiologists should attempt to produce medium‐range forecasts for allergenic pollen that cover the same time period as the weather forecasts.Objective the objective of this study is to construct a medium‐range (7 day) forecast model for grass pollen at north London.Method the forecast models were produced using regression analysis based on grass pollen and meteorological data from 1990 to 1999 and tested on data from 2000 and 2002. The modelling process was improved by dividing the grass pollen season into three periods; the pre‐peak, peak and post‐peak periods of grass pollen release. The forecast consisted of five regression models: two simple linear regression models predicting the start and end date of the peak period, and three multiple regression models forecasting daily average grass pollen counts in the pre‐peak, peak and post‐peak periods.Results overall, the forecast models achieved 62% accuracy in 2000 and 47% in 2002, reflecting the fact that the 2002 grass pollen season was of a higher magnitude than any of the other seasons included in the analysis.Conclusion this study has the potential to make a notable contribution to the field of aerobiology. Winter averages of the North Atlantic Oscillation were used to predict certain characteristics of the grass pollen season, which presents an important advance in aerobiological work. The ability to predict allergenic pollen counts for a period between five and seven days will benefit allergy sufferers. Furthermore, medium‐range forecasts for allergenic pollen will be of assistance to the medical profession, including allergists planning treatment and physicians scheduling clinical trials.

Airborne olive pollen counts are not representative of exposure to the major olive allergen Ole e 1

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.

The Onset, Course and Intensity of the Pollen Season

The onset, duration and intensity of the period when pollen is present in the air varies from year to year. Amongst other things, there is an effect upon the quality of life of allergy sufferers. The production and emission of pollens are governed by interacting environmental factors. Any change in these factors may affect the phenology and intensity of the season. Readiness to flower in a plant, and the amount of pollen produced, is the result of conditions during an often long period foregoing flowering. When a plant is ready to flower, temporary ambient circumstances e.g., irradiation and humidity, determine the timing of the actual pollen release. In order to understand variation between years and to be able to safely predict future situations, not least due to the ongoing climate change, it is necessary to know the determinants of all related processes and differences between and within species, here reviewed.

Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographic location and time in season

BACKGROUND Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergen from pollen. OBJECTIVE We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe. METHODS Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen levels were determined with a Phl p 5-specific ELISA in 2 fractions of ambient air: particulate matter of greater than 10 μm in diameter and particulate matter greater than 2.5 μm and less than 10 μm in diameter. Mediator release by ambient air was determined in FcεRI-humanized basophils. The origin of pollen was modeled and condensed to pollen potency maps. RESULTS On average, grass pollen released 2.3 pg of Phl p 5 per pollen. Allergen release per pollen (potency) varied substantially, ranging from less than 1 to 9 pg of Phl p 5 per pollen (5% to 95% percentile). The main variation was locally day to day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen levels per cubic meter (r(2) = 0.80, P < .001) than with pollen grains per cubic meter (r(2) = 0.61, P < .001). In addition, pollen released different amounts of allergen in the non-pollen-bearing fraction of ambient air, depending on humidity. CONCLUSION Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is in addition to variations in pollen counts. Molecular aerobiology (ie, determining allergen in ambient air) might be a valuable addition to pollen counting.

Spread of invasive ragweed: climate change, management and how to reduce allergy costs

* Ragweed Ambrosia artemisiifolia L. is rapidly spreading in Europe. Its pollen is highly allergenic, with 4–5 of Europeans being sensitized. There is an urgent need to curtail the further spread to minimize allergy costs. * We simulated the spread of ragweed in Austria and southern Germany (Bavaria) until 2050 with particular emphasis on expected climate change. Using different management scenarios and levels of management effort, we analysed the potential for reducing human allergy costs, that is, expenses caused by allergies from ragweed pollen, by curtailing the accelerating spread of ragweed. We accounted for three contrasting climate assumptions: no change in temperature and moderate (annual temperature increase of 0·025 °C) and more extreme (annual temperature increase of 0·04 °C) climate change. * We found that a carefully designed management plan consisting of survey and eradication can drastically reduce the spread of ragweed. Without management, mean allergy costs for the management period (2011–2050) amount to about 290, 335 and 365 million € annually under the three climate change assumptions. * Following an optimally allocated management strategy with an annual budget of 30 million € reduces mean allergy costs by 258, 295 and 325 million € per year. Thus, the management may yield substantial savings, in particular under more extreme warming, where total savings over 40 years amount to about 12 billion €. * Synthesis and applications. Our study illustrates that management of invasive alien species has an economic benefit beside natural conservation. We provide guidance for the future management using the example of ragweed in Austria and Bavaria and show that although the species has expanded its range and abundance substantially in recent years, a well-designed and ambitious management programme still may yield substantial benefits. This is true for current climatic conditions as well as for future climate change scenarios, albeit management costs increase with a warming climate. However, possible gains are increasing in parallel. Given the scale of impacts on human health, and the substantial gains accrued from management, our results suggest that it is wise to halt further spread of ragweed.

Identification of potential sources of airborne Olea pollen in the Southwest Iberian Peninsula.

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 (south-western Spain) and Évora (south-eastern 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 during conditions with slow air mass movements. 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 that examine sources and the atmospheric transport of pollen 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.