Occurrence of airborne pollen in Finland has been studied for 10 years in Turku (southern Finland), 8 years in Oulu, 4 years in Kuopio (central Finland) and 7 years at Kevo (northern Lapland). Observations on the pollen seasons of alder, birch, grasses and mugwort are presented. All these pollens occur in south and mid- Finland in quantities capable of causing allergy symptoms. Except for birch pollen, allergenic pollens occur in far lower concentrations than in central Europe. In northern Lapland only birch and pine pollen concentrations are high. Pollens may occur without signs of local flowering when there are southerly winds. This finding suggests that long-distance transport is an essential contributing factor to the occurrence of pollens. There are wide year-to-year variations in the start of pollen seasons and the quantities of pollens. The variations in the start of birch and grass pollen seasons could very much depend on the mean temperature in April. However, a forecasting model based on this and other spring-time temperature parameters often fails to give sufficiently accurate forecasts.
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.
Erratum In: Int J Biometeorol. 2003 Mar;47(2):113-5
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.
To show that Denmark obtains significant quantities of birch pollen from Poland or Germany before the local trees start to flower.
Simultaneous observations of pollen concentrations and phenology in the potential source area in Poland as well as in Denmark were performed in 2006. The Danish pollen records from 2000 to 2006 were analysed for possible long-range transport episodes and analysed with trajectories in combination with a birch tree source map.
In 2006, high pollen concentrations were observed in Denmark with bi-hourly concentrations above 500 grains/m(3) before the local trees began to flower. Poland was identified as a source region. The analysis of the historical pollen record from Copenhagen shows significant pre-seasonal pollen episodes almost every year from 2000 to 2006. In all episodes, trajectory analysis identified Germany or Poland as source regions.
Denmark obtains significant pre-seasonal quantities of birch pollen from either Poland or Germany almost every year. Forecasting of birch pollen quantities relevant to allergy patients must therefore, take into account long-range transport. This cannot be based on measured concentrations in Denmark. The most effective way to improve the current Danish pollen forecasts is to extend the current forecasts with atmospheric transport models that take into account pollen emission and transport from countries such as Germany and Poland. Unless long-range transport is taken into account, pre-seasonal pollen episodes will have a full allergic impact, as the allergy patients in general will be unprotected during that time.
The distribution of allergens, found on thorough allergy work-up in a series of 770 patients with seasonal and perennial nasal symptoms, is reported. The percentages of positive reactions to grass, tree, and herb pollens were equally high (30--40%) but, clinically, pollens from grasses (Timothy, Alopecurus, Kentucky Blue and Meadow fescue), birch and mugwort (Artemisia) were the most important. In the Nordic countries house dust is evidently the commonest causative agent in perennial rhinitis but the heterogenous composition of house dust makes it difficult to determine potent allergenic factors. Sensitivity to house dust was present in 44% of the patients; a positive reaction to mite extract in only 10%. Animal danders were not found to be great importance in allergic rhinitis (13--18%). Reactions to moulds were observed in 9% of the patients.
Symptoms of pollen allergy in springtime in Middle and Northern Europe are mainly caused by pollen grains of birch, hazel and alder. The aim of the present study was the pollen fall comparison of the mentioned taxa in Lublin (Poland) and Skien (Norway). These sites are located approximately 1,200 km away apart by air. The pollen monitoring was carried out by gravimetric method in 1999-2000. The start and end of pollen seasons were defined by the 90% method. The beginning of pollen seasons for Corylus and Betula were observed 1-3 weeks earlier in Lublin than in Skien, but pollen grains of Alnus appeared simultaneously in both towns. In 1999, annual totals of Alnus, Corylus and Betula pollen grains were considerably less numerous in Skien than in Lublin. No important differences were observed among the pollen fall amounts of the mentioned taxa in 2000. The maximum values of pollen grains were defined in different terms. The results of investigations differed as regards the years compared as well as the sites.
A modified depression rating scale was distributed to a sample of the adult Finnish population (n = 1000) in November 1991. No dependence on latitude (60 degrees N-70 degrees N) was seen in the occurrence of depression. The depressed subjects (n = 54) were reevaluated the following May, and four cases with seasonal affective disorder were found. The results suggest that high latitudes with large variations in the daily lightperiod may not be responsible for high prevalence of major depression with a seasonal pattern.
Ragweed is the dominant type of the atmospheric spora of North America. In this paper we present a forecasting model based on the probabilistic distribution of pollen curves, which was applied to four years of sampling. Except for rapid (24 hours) but large fluctuations of the pollen concentration, our algorithm allows for an adequate estimate of the exposure risk. However, these rapid fluctuations can account for up to 40% of the annual pollen sum.