Mervi Hjelmroos

Atmospheric birch (Betula) pollen in Europe: Trends and fluctuations in annual quantities and the starting dates of the seasons

Abstract Long term observations of atmospheric pollen offer the possibility of studying patterns in fluctuations in the airborne pollen presence. In this study, birch pollen measured at five monitoring stations in Europe with records of 18 to 30 years, have been analysed comparatively on three aspects: trends and fluctuations of annual sums of daily concentrations, and starting dates of airborne presence. The results show weakly rising trends at all five stations. The observed fluctuations in airborne birch pollen quantities are suggestive of synchronous, alternatingly cyclic rhythms, beit with a-synchronous aberrant years and phase shifts. For the starting dates of the birch pollen season the air temperature during the preceding 4 decades-of-days are of decisive importance.

Evidence of long-distance transport of betula pollen

Abstract In April the eastern parts of Fennoscandia are frequently influenced by south to southeastern winds. These air-masses can bring with them large quantities of Betula pollen several weeks before the local flowering season begins. The pollen is transported with air-masses at a high level and then taken down by turbulent transport or washout. The number of pollen grains can be so high that sensitive persons exhibit allergic symptoms. Three localities from Sweden and six from Finland have been selected and numerical air-parcel trajectories have been calculated in order to determine the Betula pollen source. The results indicate that the distant pollen source areas can be identified, and that the travelling times for pollen grains transported in April 1989 were mostly in the range of 9 to 20 hours.

Relationship between airborne fungal spore presence and weather variables: Cladosporium and Alternaria

Abstract By means of regression analysis the Cladosporium and Alternaria spore counts for 1980–89 for Stockholm are explored and modelled at 6-hour intervals in order to find the relationship between spore presence and climate for the same time periods. Six different weather parameters are used. For Cladosporium daily mean temperature and daily precipitation seem to be consistently significant. The presence of Alternaria appears to be more complex. There is a tendency for Alternaria spore concentrations to increase with the daily precipitation, wind velocity and total cloud cover. The models are evaluated statistically. On the basis of 10 years of data from roof level in Stockholm the natural background load of Cladosporium and Alternaria as the most prevalent fungal aeroallergens is presented and discussed.

The ‘yellow snowepisode’ of northern Fennoscandia, march 1991—A case study of long-distance transport of soil, pollen and stable organic compounds

Abstract The present paper describes a vast dustfall with snow in northern Fennoscandia, 10 March 1991. The area affected by dust deposition was at least 320,000 km2. and the particulate mass received amounted to between 50 and 200 mgm−2. The total amounts of dust deposited in the investigated area sum up to approximately 50,000 tonnes. The dust consisted of soil particles, i.e. single mineral grains and loose ferric aggregates of mineral grains in addition to pollen and spores. Mineralogically, the dust was dominated by small rounded quartz grains. Median size of the dust particles was 2.72 μm. The total pollen concentration varied from 327 to 1172 pollen cm−2. The pollen types identified were divided in “Nordic/Central European” taxa and “Exotic” taxa. Pollen from the former group, e.g. Betula, Alnus and Corylus were believed to originate in the Alps and in the northern parts of Central Europe where these species were flowering. The latter category was considered to originate in more remote areas, many of them belonging to the taxa growing only around the Mediterranean. From a paleo-ecological point of view, long-distance transport such as this would count for an important potential source of error whenever interpreting Holocene pollen diagrams. The content of stable organic compounds showed that the dust was relatively clean, compared to other episodes, when the dust deposited had originated in heavily polluted regions. The small amounts of chlorinated hydrocarbons, polychlorinated biphenyles (PCB), polyaromated hydrocarbons (PAH) and other hydrocarbons found, are believed to have been adsorbed by the particle surfaces during transportation. The results of the study, along with meteorological data, lead to the conclusion that the material originated in North Africa. Dust mobilization was reported in Tunisia as well as in Algeria. This means that the dust was transported at least 7000 km before deposition.

Implications of recent long-distance pollen transport events for the interpretation of fossil pollen records in Fennoscandia

Abstract Under favourable conditions, a considerable amount of long-distance transported pollen can be deposited far from its place of origin. In Fennoscandia, in most cases, such situations occur when there is a strong southerly air circulation from South-Europe and/or North-Africa. Soil particles and pollen grains associated with the top soil or the present vegetation, can be lifted up by strong surface winds and brought up to higher levels, where further transportation takes place. During the last few years several of these events have been reported. The pollen analysis of three events with coloured precipitation from different parts of Fennoscandia provides information about such exotic pollen rain and its extent. The quantity of exotic pollen in the snow samples analysed is high, generally in the range of 500–2000 pollen grains cm −2 per episode. However, the amount of transported pollen can even be as great as that deposited during local anthesis in the same year, and influx values can exceed 30, 000 pollen grains cm −2 per few hours of snowfall. The results are analysed in relation to trajectory calculations, the actual phenological data, and pollen concentrations monitored by volumetric sampling from the air. Since the long-distance transport of pollen grains depends mainly on climatological factors, the hypothesis that exotic pollen deposition was common throughout the whole of the Holocene in Fennoscandia is presented. Long-distance transport of pollen grains can, therefore, be regarded as a potential source of error in the interpretation of Holocene pollen diagrams from Fennoscandia.

Allergic symptoms caused by long-distance transported birch pollen

Abstract Birch pollen allergy is very common in northern Sweden, and the local flowering season never starts before the middle part of May. In the last week of April 1989 patients with birch pollen allergy developed typical symptoms requiring treatment. This pattern was confirmed in a group of patients who registered their symptoms in diaries, while contemporaneous pollen measurements demonstrated high amounts of birch pollen in the air. At that time in the northern part of Sweden, however, no birches were flowering. Meteorological data indicated that strong winds from the south-east during the period transported birch pollen from the Baltic states. Similar weather conditions in 1982, 1984 and in 1990 have also resulted in high amounts of birch pollen in the air long before the local flowering season. It is concluded that long distance transport of pollen may result in clinically significant allergy problems before, and even after the normal local season.

Heterogeneity of Pollen Proteins within Individual Betula Pendula Trees

To determine the variation of antigenic water soluble proteins in white birch (Betula pendula) pollen, extracts of pollen from different sides of individual trees were analyzed by isoelectric focusing (IEF), crossed immunoelectrophoresis, and crossed radioimmunoelectrophoresis. IgE-antibody-binding patterns were also studied in samples analyzed by IEF by probing with serum pooled from patients with birch pollen allergy, followed by radiolabelled anti-IgE. Antigenic proteins and allergens per unit weight of extracted protein were greatest in pollen extracts from the south side of the trees. Allergens decreased progressively in pollen from west-through east- to north- facing branches. Proteins with high isoelectric points (pI > 8.5) and proteins between pI 4.5 and 5.6 were infrequent in extracts from the north side. Extracts from branches facing north were poor in allergens: in general, only one or two precipitin lines were found, and in some cases they did not bind to IgE antibodies. Differences between numbers of proteins and allergens found in extracts from south, west and north branches were statistically significant for all methods used. The results indicate the need to collect birch pollen for allergen extract manufacture from south-facing branches.

Long-distance transport ofBetula pollen grains and allergic symptoms

SummaryAn example of the potential importance of air masses as carriers of aero-allergens from distant source areas is provided. Considerable amount ofBetula pollen is relatively often transported to Fennoscandia before the local birch flowering period, mainly by southeastern air masses from eastern part of central Europe. Although the distance and the transport time in some cases can be extensive, the pollen grains seem to cause allergic reactions among sensitive persons.A comparison between the clinical results andBetula pollen counts from the time before the local flowering season in Stockholm in 1989 is presented.

Detection and quantification of airborne birch pollen allergens on PVDF membranes by immunoblotting and chemiluminescence

Abstract Birch pollen and antigens were collected on sampling tape of the Burkard Seven-day-recording Pollen and Spore Trap before, during and after the pollen season. The antigens were then transferred to a polyvinylidene difluoride (PVDF) membrane. For detection and quantification of the antigens a double antibody system and chemiluminescence was used. The chemiluminescence-chemicals emit light at positions in the membrane where antigen is present. The light produced was documented by contact of the blotting membrane with x-ray film, and also measured with a newly developed luminometer. Birch pollen antigenic activity was found on the tapes a few weeks before the local incipient birch pollen season although no birch pollen grains were monitored on a control tape for allergy information service. The concentration of small antigenic particles present in the air after rainfall is discussed.

Adhesive tapes as capturing surfaces in Burkard sampling

Although pressure‐sensitive adhesive tapes appear to offer many advantages over traditional adhesives in sampling with a Hirst‐type spore trap, their particle capturing efficiency has never been documented. In this paper, the particle capture efficiency of four pressure‐sensitive adhesive tapes was compared to the standard vaseline adhesive in the Burkard 7‐day volumetric spore trap. The capture efficiency was assessed at flow rates of 8 and 101 min−1 over a 16 week period with each tape run alongside the standard. Image analysis was used to count and measure the surface area of individual inorganic and organic particles collected onto each tape. Approximately 230,000 individual particles were analysed, the majority of particles collected on both standard and pressure‐sensitive adhesive tapes had a surface area less than 150 μm2 (approximately diameter 14 μm). Capture efficiency was expressed as a percentage of the counts on the standard and classified by particle size and flow rate. For particles < 1000 ...