Airborne pollen characteristics and the influence of temperature and precipitation in Raleigh,North Carolina,USA (1999–2012)

The incidence of allergic diseases has been increasing in recent decades, in part due to increased exposure to aeroallergens, particularly pollen. Allergic diseases have a major burden on the health care system, with annual costs in the USA alone exceeding $30 billion. There is evidence that the production of aeroallergens, including pollen, is increasing in response to environmental and climatic change, which has important implications for the treatment of allergy sufferers. In this study, pollen data from a Rotorod sampler in Raleigh, North Carolina, was used to characterize and examine trends in the atmospheric pollen seasons for trees, grasses, and weeds over the period 1999–2012. The influence of mean monthly antecedent and concurrent temperature and precipitation on the timing, duration, and severity of the pollen seasons was assessed using Pearson’s product-moment correlation coefficients and multiple linear regression models. An increasing trend was noted in seasonal tree pollen concentrations, while seasonal and peak weed pollen concentrations declined over time. The atmospheric pollen seasons for grasses and weeds trended toward earlier start dates and longer durations, while the tree pollen season trended toward an earlier end date. Peak daily tree pollen concentrations were strongly associated with antecedent temperature and precipitation, while peak daily grass pollen concentrations were strongly associated with concurrent precipitation. The strongest relationships between climate and weed pollen were associated with the timing and duration of the pollen season, with drier antecedent and warmer concurrent conditions tied to longer weed pollen seasons.     

The influence of temperature,relative humidity and rainfall on the occurrence of pollen allergens (Betula,Poaceae, Ambrosia artemisiifolia) in the atmosphere of Bratislava (Slovakia)

The occurrence of pollen grains in the atmosphere markedly relates to meteorological factors. In the study we have evaluated a correlation between the concentration of pollen grains in the atmosphere of Bratislava and temperature, relative humidity and rainfall during the vegetation period of 1995 and 1997. For our analysis we have selected one representative of each phytoallergen group (trees, grasses, weeds). We have chosen the Betula genus of trees, the whole Poaceae family of grasses and ragweed Ambrosia artemisiifolia L. to represent weeds. The taxons mentioned represent the most significant allergens in Slovakia. The concentration of pollen grains has been monitored by a Lanzoni volumetric pollen trap. The data obtained, the average daily concentration in 1 m(3), have been included in the statistical analysis together with values for the average daily temperature, relative humidity and total rainfall in 24 h. The correlation between the concentration of pollen grains in the atmosphere and selected meteorological variables from daily monitoring has been studied with the help of linear regression and correlation coefficients. We have found the average daily temperature and relative humidity (less than temperature) to be significant factors influencing the occurrence of pollen grains in the atmosphere of Bratislava. The total daily rainfall does not seem to be significant from the statistical point of view.     

An annual study of airborne pollen in northern Mexico City

An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00.     

An annual study of airborne pollen in northern Mexico City

An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00.     

Grasses, olive, parietaria and cypress in Athens: Pollen sampling from 1995 to 1999

The airborne pollens can produce asthma andrhinoconjuctivitis (pollinosis). Sincegeographic and climatic factors influence thequality and quantity of pollen counts invarious countries and between seasons, the aimof the study was to record major seasonalallergenic pollens; grasses, olive, parietariaand cypress in Athens during five consecutiveseasons throughout the years 1995–1999. Thedaily pollen count was carried out every yearfrom March to October using a Burcardvolumetric weekly spore trap, which was placedabout 20 m from the ground, in Athens citycentre. Daily values were expressed as numberof pollen grains/m³ of air. The meanmonthly values of pollens/m³ were used tocompare the results of the consecutive years.Recording of the major pollen allergens inAthens area for five consecutive years led tothe assessment of the pollination period foreach of these plants and confirmed thevariations in the amount of pollen per plantper year.     

Thirty-four years of pollen monitoring: an evaluation of the temporal variation of pollen seasons in Belgium

For the first time in Belgium, fluctuations in airborne pollen quantities over a 34 years period have been analyzed. Seven pollen types have been selected comprising the most clinically relevant in Belgium nowadays (birch, alder, hazel and grasses) and others that are known to be allergenic in other European countries and frequently found in Belgium (plane, ash and mugwort). Pollen monitoring was performed with a seven-day recording volumetric spore trap placed in Brussels. We measured increasing airborne pollen for four trees, namely alder, hazel, ash and plane. Although the total pollen index for birch has not increased significantly, an increasing trend in the annual amount of days above the concentration threshold of 80 pollen grains/m³ was clearly observed. Concerning temporal variations, the pollen season has tended to end earlier for birch, ash and plane and the peak concentration of the pollen of plane has been appearing earlier in the year. In the investigated period, the pollen seasons of grasses and mugwort have tended to become less severe. Furthermore, we reported a temporal shift of the grass pollen season, beginning and ending earlier, together with an advance of the annual peak date.     

Evaluation of indoor passive pollen sedimentation over 1 year: a possible source of contamination?

The study aimed to evaluate the possible contamination by passive indoor pollen sedimentation in a laboratory where routine pollen analyses were conducted, but where no particular laboratory policies were adopted to limit contamination. Gravimetric pollen deposition was observed on traps (petri dishes soaked with glycerol) set in the palynology laboratory, under an extractor hood and on the bench beside it over 1 year (1995–1996), and in an air filtered room in a flow cabinet and on its roof over 1 month for comparison. Under the extractor hood, three types of airborne particles were deposited: pollen grains, spores and algae, representing 32.35, 67.28 and 0.37%, respectively, of the total sedimented particles over 1 year. The number of pollen grains deposited on the surface trap ranged from 0 (27 November to 4 December 1995) to 707 (10–18 April 1995). The highest number of taxa during a weekly collection was 23 (9–15 May 1995). The pollen flora represented by anemophilous pollen (>90% of the trapped pollen) was related to the vegetation next to the laboratory:Acer, Carpinus, Castanea, Corylus, Cupressaceae, Pinus, Quercus, Salix, Taxus for trees and shrubs andArtemisia, Brassicaceae, Plantago, Poaceae, andUrticaceae for grasses and weeds. Indoor pollen deposition corresponded to the period of the outdoor pollination (macroscopic field observation) which lasted from March to the beginning of August. However, some pollen were almost always present in the collection (Poaceae, Salix, Castanea, Betula), reflecting the occurrence of pollen grains in the atmosphere out of the pollination period. Moreover, about five times more entomophilous pollen was found under the extractor hood compared to the other area of the laboratory; even in the flow cabinet of the air filtered room, 237 particles were captured (versus only 15 on the roof). These data suggest a possible human contamination during operations under the extractor hood or in the flow cabinet. Although few airborne pollen were found, possible contamination has to be considered in investigations where even low pollen quantities are of interest.     

A 10-year survey of allergenic airborne pollen in the city of Porto (Portugal)

Airborne pollen calendars are useful to estimate the flowering season of the different plants as well as to indicate the allergenic potential present in the atmosphere at a given time. In this study, it is presented a 10-year survey of the atmospheric concentration of allergenic pollen types. Airborne pollen was performed, from 2003 to 2012, using a 7-day Hirst-type volumetric trap. The interannual variation of the daily mean concentration of the number of pollen grains and the main pollen season was determined as well as the hourly variations and correlation with meteorological parameters. During the study period, 18 different allergenic pollen types were considered based on its representativeness on the total annual airborne pollen concentration. The lowest annual concentrations were sampled in 2006 and the highest in 2007. The highest airborne pollen concentration was found during early spring and early summer. On the contrary, December was the month with the lowest pollen concentration. The major pollen sampled belongs to trees followed by weeds and grasses, being the most representative pollen types in the atmosphere: Urticaceae, Platanus, Poaceae, Pinaceae, Cupressaceae, Acer, Quercus, Castanea, Plantago, Alnus, Olea europaea, Betula, Myrtaceae and Populus. Intradiurnal distribution patterns of the pollen types studied presented differences with some taxa being predominantly sampled in the morning (9–11 a.m.) while others in first night hours (between 9 and 12 p.m.). Significantly correlations were found between the airborne pollen concentration and meteorological parameters.     

Aerobiology of subtropical Eastern Hymalayas (Kurseong), India

Summary Aerobiology studies of subtropical Eastern Hymalayas (Kurseong) were done for two years. A total of 32 airborne pollen types were recorded along with a few fern spores. In all 4961 pollen grains were trapped during 1981–82 and 4697 during 1982–83. The data reveals seasonal variation of pollen incidence. The incidence of tree pollen dominated over grasses and weeds. The trapped tree pollen originated fromAlnus, Betula, Engelhardtia, Quercus, Bucklandia, Acer, Salix, Ilex, Cryptomeria, Pinus, Cupressus, etc. among others, some of which are known to be allergenically significant in Kurseong. The pollen grains of weeds likeUrtica, Plantago, Cannabis, Rumex, Amaranthaceae, Chenopodiaceae etc. are also proved to be allergenically significant in Kurseong. Grass pollen grains established as highly allergenic, occurred in large amount round the year. The seasonal variation of pollen incidence was dependent mainly on variable flowering periods and climatic variations.     

Oleaceae in Trieste (NE Italy): aerobiological and clinical data

Oleaceae pollen concentrations in the Trieste area are low (<10%) compared to the total number of airborne pollen grains, with only one pollination peak at the beginning of June when the Oleaceae concentration reached 62% of the total pollen count in 1992. This peak was due to an exceptionally high pollination of olive trees in 1992, when airborne pollen concentration rose to 1357 pollen grains/m³ on June 3. Sensitization toOlea increased from 1989 to 1993, when it was present in 23.4% of symptomatic patients, but the role ofOlea in inducing allergic respiratory symptoms is difficult to evaluate because almost all patients were sensitized to other pollens, and in particular to Gramineae: only four subjects were sensitized toOlea alone (1.4%). Despite the low Oleaceae pollen counts, this pollinosis is increasing, probably because of increased cultivation ofOlea in recent years. However, although skin prick test positivity is common in polysensitized patients, its role in inducing sensitization and symptoms is presently less important than that of other pollens.     

Temporal and spatial distribution of atmospheric Poaceae pollen in Catalonia (NE Spain) in 1996–2001

A preliminary study to compare Poaceae pollen data and to determine possible differences in pollen productivity and/or seasonality was performed at six locations in Catalonia (Spain): Barcelona, Bellaterra, Girona, Lleida, Manresa and Tarragona over a 6-year period (1996–2001). In the study area, Poaceae pollen grains are an important cause of respiratory allergies. Being present in the atmosphere all year round, the grass pollen concentrations are especially significant between May and August. The absolute peak occurs in June, except in Lleida where the peak comes earlier, possibly due to the early flowering of particular steppe species. Even if there are differences between different years, Girona and Lleida (inland locations) usually present the highest annual grass pollen index with, on average, 2177 pollen grains per year. Barcelona and Tarragona (the coastal sites) show the lowest levels, with around 1140 grass pollen grains per year. The respective local climates are very different, and pollen grains may originate in different grass species. A decreasing trend in the Poaceae annual pollen index was found over the period of the present study.     

A metabolomic,geographic, and seasonal analysis of the contribution of pollen-derived adenosine to allergic sensitization

Background

Studies on ragweed and birch pollen extracts suggested that the adenosine content is an important factor in allergic sensitization. However, exposure levels from other pollens and considerations of geographic and seasonal factors have not been evaluated.

Objective

This study compared the metabolite profile of pollen species important for allergic disease, specifically measured the adenosine content, and evaluated exposure to pollen-derived adenosine.

Methods

An NMR metabolomics approach was used to measure metabolite concentrations in 26 pollen extracts. Pollen count data was analyzed from five cities to model exposure.

Results

A principal component analysis of the various metabolites identified by NMR showed that pollen extracts could be differentiated primarily by sugar content: glucose, fructose, sucrose, and myo-inositol. In extracts of 10 mg of pollen/ml, the adenosine was highest for grasses (45 µM) followed by trees (23 µM) and weeds (19 µM). Pollen count data showed that tree pollen was typically 5–10 times the amount of other pollens. At the daily peaks of tree, grass, and weed season the pollen-derived adenosine exposure per day is likely to be only 1.1, 0.11, and 0.12 µg, respectively. Seasonal models of pollen exposure and respiration suggest that it would be a rare event limited to tree pollen season for concentrations of pollen-derived adenosine to approach physiological levels.

Conclusion

Sugar content and other metabolites may be useful in classifying pollens. Unless other factors create localized exposures that are very different from these models, pollen-derived adenosine is unlikely to be a major factor in allergic sensitization.

     

北京城区气传花粉季节分布特征

研究北京城区气传花粉种类、数量及季节消长规律,为防治花粉症及建设合理城市绿地提供有效资料.应用Burkard采样器于2010年12月31日至2011年12月31日对北京城区气传花粉浓度进行监测,并对花粉浓度进行统计学分析.研究结果显示,2011年北京城区的花粉季节从3月20日起始,至10月18日截止,持续213d,占全年天数的58％;全年花粉含量月分布呈现两个高峰,第1个高峰为3-4月,主要花粉为木犀科、杨属、柳属等树木花粉,占全年花粉总量的30％;第2个高峰为8-9月,主要花粉为菊科、藜科及苋科等莠草花粉,占全年花粉总量的50％;2011年度北京城区最具代表性的气传花粉来自于菊科,比重占了收集到气传花粉的35％.研究结果还表明,秋季的气传花粉致敏性强,所以北京花粉症的高发季节主要集中在秋季,以8-9月为最高,其中有95％的病人在此期间出现花粉症症状.花粉浓度及飘散规律受当地植被状况及气候等多种因素影响,因此,北京城区空气中气传花粉飘散种类、数量及季节分布规律的调查结果,可以为本地区花粉症防治及绿化品种的选择提供可靠依据.     

Digestibility of columnar cacti pollen grains in the glosophagine bats Glossophaga longirostris and Leptonycteris curasoae (Chiroptera: Phyllostomidae)

We examined the protoplasmic assimilation of columnar cacti pollen grains in two species of Venezuelan desert glosophagine bats, Glossophaga longirostris and Leptonycteris curasoae, by determining the amount of empty (digested) pollen grains found in their fecal samples. To determine the amount of empty pollen grains, the fecal samples were stained to differ between empty and full (non-digested) pollen grains. The number of empty and full pollen grains observed in the fecal samples were corrected using the amount of aborted pollens present (before anthesis) in flowers of the columnar cacti species (Subpilocereus repandus, Stenocereus griseus and Pilosocereus tillianus) used by bats as food in the study site; G. longirostris and L. curasoae digested 64.2% and 71.3% of all the pollens fed, respectively. These high values confirm the importance of pollen in the diet of these bats, given its high nitrogen level.     

Poaceae pollen in the atmosphere of Aranjuez,Madrid and Toledo (central Spain)

The main aim of this work is to study the aerobiological behaviour of Poaceae pollen in three areas of central Spain (Aranjuez, Madrid and Toledo), all of which are similar from a geographical, climatic and biogeographical point of view, and they are located nearby one another. The samplings were carried out over a period of 4 years (2005–2008) using Hirst-type spore traps. Grass pollen is responsible for most spring allergic reactions in the pollen-sensitive population in central Spain, and they are very abundant in the atmosphere of this part of Iberian Peninsula. The average amount of this pollen type, as a percentage of the annual total pollen amount, is 7.4% in Aranjuez, 9.2% in Madrid and 11.3% in Toledo. Poaceae pollen is present in the atmosphere over a long period of time (February–October), and its maximum concentrations are detected during May and June (weeks 16–25). The city of Toledo has the highest annual concentrations of grass pollen (average 5,797 grains) with a great number of days exceeding the allergy thresholds proposed by the Spanish Aerobiology Network (REA). Madrid and Aranjuez present similar annual concentrations of grass pollen with values of 2,961 grains and 2,751 grains, respectively. The correlation analysis between the daily levels of grass pollen and meteorological variables of temperature and rainfall show a significant correlation, positive with temperature (maximum, mean and minimum) and negative with rainfall.     

Seasonal distribution of airborne pollen in the coastal plain of Israel

Airborne pollen was monitored in three major urban centers of the coastal plain of Israel during the years 1993–1995. Results show spatial and temporal variations among the three sites. Altogether, the number of identified species was rather low. Ornamental trees (Cupressaceae,Pinus, Olea, Casuarina, Ceratonia) and grasses, have constituted the main source of the pollen rain. A substantial contribution of the wild plants of the region was restricted toParietaria, Urtica, Mercurialis, Artemisia, grasses and members of the Chenopodiaceae and Amaranthaceae.     

Study of seasonal and daily variations in airborneOlea europaea L. pollen in Jaén (Spain), 1993–1995

A study is made of the seasonal and daily variations in the concentrations of pollen ofOlea europaea L. over three consecutive years (1993–1995) in the atmosphere of Jaén (southern Spain). A Burkard volumetric spore trap was used for sampling. The results show that the highest concentrations of airborne olive pollen occur during May and the first 2 weeks of June, when levels often exceed 500 grains/m³ and occasionally reach nearly 5000 grains/m³ (the levels of allergenic pollen in the atmosphere of Jaén are among the highest in Europe). Over the 3-year study period a significant seasonal variation was detected, not only in the development of the principal pollination period, but also in the value of the maximum pollen concentrations recorded.     

Shape and Size Modification of Recent Pollen Grains under Acetolysis

In this paper, the shape and size modification of recent pollen grains have been studied. 63 species of recent pollen grains that belongs to 55 genera, 26 families were observed before and after the acetolysis treatment with LM. The length of polar axis and equatorial axis and the thickness of exine were measured from about 20 pollen grains for each species (the thickness of exine were only measured for acetolysed pollen grains). The significance of shape and size modification was examined with the statistical method "ttest". From this investigati0n it can be concluded that: The pollen modification in size and shape 'was related to aperture type, pollen size, wall thickness and sculpture depth. Pantoporate, spheroidal pollens and small perporlate pollens usually change little in there size and shape after acetolysis. The size of colpate pollens was generally increased, or their shape changed. The size or shape change usually got bigger as the pollen size, wall thickness and sculpture depth became bigger and bigger. Oblate pollens were apter to change their size and shape than prolate pollens. The P/E ratio of most colpate pollens became a little bigger after acetolysis.     

Airborne pollen from allergenic herbaceous plants in urban and rural areas of Western Pomerania,NW Poland

This paper presents the course of the pollen season of selected allergenic taxa (Rumex spp., Plantago spp., Urtica spp. and Chenopodiaceae) in two towns with different degrees of urbanisation (urban, the city Szczecin, and rural, the village Gudowo in Western Pomerania, northwest Poland). The study was conducted in the years 2012–2014 with the volumetric method. The pollen of allergenic herbaceous plants was present in the air from early May until the end of September. From among the taxa studied, the genus Rumex is characterised by the longest pollination period, while the genus Urtica by the shortest. The highest percentage contribution of pollen grains to the total pollen count in the air reaching over 90% is from nettle. The pollen seasons determined for the majority of taxa are longer in the city, however the mean pollen grain counts in the air are higher for the rural area.     

The morphology and ultrastructure of Jurassic in situ ginkgoalean pollen

A fragmentary pollen organ with four to six microsporangia is discovered from the Middle Jurassic of the Irkutsk coal basin, Siberia. The in situ pollen grains are boat-shaped, monosulcate, and with a nearly psilate surface. The non-aperture ectexine is composed of a thick solid tectum, a thin infratectum, and a thin foot layer. The infratectum includes one row of small rare alveolae. The supposedly poorly preserved endexine is thin and grainy. The ectexine reduces greatly in the aperture area, where only homogeneous ectexinal patches are present over the endexine. The pollen grains under study resemble in their exine ultrastructure pollen grains of the modern Ginkgo biloba and pollen grains from dispersed seeds of a presumably ginkgoalean affinity from the Middle Jurassic of Uzbekistan. This suggests that the ginkgoalean exine ultrastructure of the modern type existed as early as the Middle Jurassic. The exine ultrastructure under study is also similar, though to lesser degree, to that of dispersed pollen grains of a presumed ginkgoalean affinity from the Cretaceous of the Russian Far East. The diversity of such a long-living group as ginkgoaleans is apparently reflected in the diversity of their exine ultrastructure. To the present knowledge, ginkgoalean pollen grains can be differentiated from similar boat-shaped monosulcate pollens by the following co-occurring characters: a thick homogeneous tectum, a thin infratectum with one row of structural elements, a thin foot layer, and an ectexine that is reduced in the aperture region to patches.