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The dataset presents a 43 year-long reanalysis of pollen seasons for three major allergenic genera of trees in Europe: alder (Alnus), birch (Betula), and olive (Olea). Driven by the meteorological reanalysis ERA5, the atmospheric composition model SILAM predicted the flowering period and calculated the Europe-wide dispersion pattern of pollen for the years 1980-2022. The model applied an extended 4-dimensional variational data assimilation of in-situ observations of aerobiological networks in 34 European countries to reproduce the inter-annual variability and trends of pollen production and distribution. The control variable of the assimilation procedure was the total pollen release during each flowering season, implemented as an annual correction factor to the mean pollen production. The dataset was designed as an input to studies on climate-induced and anthropogenically driven changes in the European vegetation, biodiversity monitoring, bioaerosol modelling and assessment, as well as, in combination with intra-seasonal observations, for health-related applications., (© 2024. The Author(s).)

Introduction and Objective: Species of the genus Artemisia (Asteraceae) are weeds and ruderal plants growing in northern temperate regions of the world. Many of them are used in medicine and the cosmetic industry and for culinary purposes. Pollen grains of plants of this genus contain the most important aeroallergens., Material and Methods: An aerobiological study conducted with the volumetric method in Lublin in 2001-2022. Trend lines for the season parameters were established. Spearman's correlation and stepwise regression analyses were carried out to determine relationships between various parameters of the pollen season and meteorological factors. PCA analysis was also carried out to visually compare the pollen seasons., Results: In Lublin, central-eastern Poland, the Artemisia pollen season lasted on average from the second ten days of July to the end of August, with its beginning depending on the temperature in April and May. The highest pollen concentrations were mainly recorded in the first half of August and were largely dependent on the mean temperature in June and July. The second peak in the pollen season recorded in September was associated with the presence of Artemisia annua pollen. Intense sunshine in June and the higher temperatures in June and July resulted in significant reduction in the Artemisia annual pollen sum (by 65%) over 22 years. Artemisia vulgaris is abundant in the Lublin region and contributes substantially to the amount of Artemisia pollen in the aeroplankton., Conclusions: The downward trend in the amount of Artemisia pollen was a result of the increase in temperatures observed in the summer months, and the declining rainfall rates. The global warming effect is extremely unfavourable for plants of Artemisia vulgaris, as they require moist soil substrates for growth.

Birch belongs to the most important allergenic taxa in Europe, therefore information on the start dates of the pollen season is very important for allergists and their patients as well as for climatologists. The study examined changes in the start of the birch pollen season as well as determined the trend of these changes. Pollen monitoring was performed in Lublin (eastern Poland) in the period 2001-2019 using the volumetric method. The Makra-test was used to detect periods with significantly higher or lower average of the onset than the average for the whole dataset. Two significant falls in the average of the pollen season start were found in 2007 and 2014. Besides, taking into account the 2-3-year rhythm of high and low concentrations of birch pollen in the atmospheric air, linear trends were fitted for the subsets of high and low abundance seasons. Significant changes in Betula pollen season start dates were only determined for the highly abundance seasons, while the results for seasons with a low concentration did not allow rejecting the hypothesis about the lack of a linear trend in the changes in the studied parameter. Moreover, a significant polynomial relationship was found between the beginning of a pollen season and the average values of monthly temperatures preceded a season. These analyses show that the start dates of the Betula pollen season are getting significantly earlier. The dynamics of changes differ between seasons with high and low concentrations of pollen., Competing Interests: The authors have declared that no competing interests exist.

In recent years, allergies due to airborne pollen allergens have shown an increasing trend, along with the severity of allergic symptoms in most industrialized countries, while synergism with other common atmospheric pollutants has also been identified as affecting the overall quality of citizenly life. In this study, we propose the state-of-the-art WRF-Chem model, which is a complex Eulerian meteorological model integrated on-line with atmospheric chemistry. We used a combination of the WRF-Chem extended towards birch pollen, and the emission module based on heating degree days, which has not been tested before. The simulations were run for the moderate season in terms of birch pollen concentrations (year 2015) and high season (year 2016) over Central Europe, which were validated against 11 observational stations located in Poland. The results show that there is a big difference in the model's performance for the two modelled years. In general, the model overestimates birch pollen concentrations for the moderate season and highly underestimates birch pollen concentrations for the year 2016. The model was able to predict birch pollen concentrations for first allergy symptoms (above 20 pollen m -3 ) as well as for severe symptoms (above 90 pollen m -3 ) with probability of detection at 0.78 and 0.68 and success ratio at 0.75 and 0.57, respectively for the year 2015. However, the model failed to reproduce these parameters for the year 2016. The results indicate the potential role of correcting the total seasonal pollen emission in improving the model's performance, especially for specific years in terms of pollen productivity. The application of chemical transport models such as WRF-Chem for pollen modelling provides a great opportunity for simultaneous simulations of chemical air pollution and allergic pollen with one goal, which is a step forward for studying and understanding the co-exposure of these particles in the air.

During the spring period, Betula pollen is the main cause of inhalant allergies in Poland and therefore it is important to monitor and forecast airborne pollen concentrations of this taxon. This study conducted a comparative analysis of the basic characteristics of Betula pollen seasons at the regional scale. The study was carried out from 2001 to 2016 in five cities in Poland: Lublin, Warsaw, Cracow, Sosnowiec, and Szczecin. To find the attributes of birch pollen seasons that mostly differentiated the individual cities, a general discriminant analysis (GDA) was performed, while a principal component analysis (PCA) allowed us to reduce the data space and present a scatterplot of PCA scores in order to compare pollen seasons in the individual cities. The contingency table was also analyzed to check whether there was a significant relationship between pollen counts in the studied years and cities. At most of the sites, biennial cycles of low and high pollen concentrations can be observed. Due to the high variation in seasons in each of these cities, two data groups were distinguished: Group 1 was composed of seasons with high pollen deposition (2001, 2003, 2006, 2008, 2010, 2012, 2014, 2016), and Group 2 comprising the other seasons. Multivariate analyses were performed on both these groups as well as in the entire dataset. End98, Peak Value, and Annual Total had the highest discriminant power. In Group 1, Warsaw and Sosnowiec differed the most in the investigated parameters, while Cracow and Szczecin differed the least. In both groups, most seasons with the highest pollen birch concentration were observed in Lublin, followed by Warsaw, while in Cracow, the number of such seasons was the smallest., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction and Objective: The timings of Fraxinus and Betula flowering and pollen release overlap, which may cause increased allergic reactions in sensitive people. The aim of the present study was to characterize Fraxinus pollen seasons in Lublin (central-eastern Poland) and to identify meteorological factors that most determine the occurrence of airborne pollen of this taxon, as well as obtain forecast models for the basic characteristics of the pollen season., Material and Methods: The study was conducted in Lublin during the period 2001-2016, employing the volumetric method. The seasons were compared by PCA (Principal Component Analysis). To determine relationships between meteorological conditions and the pattern of pollen seasons, regression analysis was used. Data for the period 2001-2015 were used to create forecast models by applying regression analysis, while the 2016 data served to verify these models., Results: Season end date and seasonal peak date were characterized by the lowest variation. The biggest differences were found for peak value and total annual pollen sum. The average dates of occurrence of ash pollen grains in the air of Lublin were between 13 April 13 - 3 May 3, whereas, on average, the pollen peak date occurred on 23 April. The factor loading values for the PC1 variable indicate that it is most strongly correlated with peak value and total pollen sum, while the PC2 variable correlated with the pollen season start date and season duration (a negative correlation). Regression models were developed for the following pollen season characteristics: season start, end and duration, seasonal peak date, and total annual pollen sum., Conclusions: The fit of the forecast models was at the level of 62-94%. Analysis of the data showed that weather conditions mainly in February were important factors controlling the Fraxinus pollen season.

An aerobiological study was conducted to investigate the quantity and quality of pollen in the atmosphere of Lublin in central-eastern Poland. Pollen monitoring was carried out in the period 2001-2012 using a Hirst-type volumetric spore trap. The atmospheric pollen season in Lublin lasted, on average, from the end of January to the beginning of October. The mean air temperature during the study period was found to be higher by 1.1 °C than the mean temperature in the period 1951-2000. 56 types of pollen of plants belonging to 41 families were identified. 28 types represented woody plants and 28 represented herbaceous plants. The study distinguished 5 plant taxa the pollen of which was present most abundantly in the air of Lublin, which altogether accounted for 73.4%: Betula, Urtica, Pinus, Poaceae, and Alnus. The mean annual pollen index was 68 706; the largest amount of pollen was recorded in April and accounted for 33.3% of the annual pollen index. The pollen calendar included 28 allergenic plant taxa. The pollen of woody plants had the highest percentage in the pollen spectrum, on average 58.4%. The parameters of the pollen calendar for Lublin were compared with the calendar for central-eastern Europe with regard to the start of the pollen season of particular taxa. The pollen calendar for Lublin was demonstrated to show greater similarity to the calendar for Münster (Germany) than to the calendar for Bratislava (Slovakia).

Pollen monitoring was carried out in Lublin in 2001-2012 by the volumetric method using a Hirst-type spore trap (Lanzoni VPPS 2000). Daily pollen concentrations considerably differed in the particular years. The pollen counts with the biggest variability were observed in the first half of a year when woody plants flowering. The highest annual pollen index were noted for the following taxa: Betula, Urtica, Pinaceae, Poaceae and Alnus. Betula annual total showed the greatest diversity in the study years. The number of days on which the pollen concentration exceeded the threshold values, thereby inducing allergies, was determined for the taxa producing the most allergenic pollen. The above-mentioned taxa primarily included the following: Poaceae, in the case of which the highest number of days with the risk of occurrence of pollen allergy was found (35), Betula (18), and Artemisia (10). The following taxa: Alnus (14 days), Populus (11 days), Fraxinus (10 days), and Quercus (8 days), were also characterized by a large number of days on which their pollen concentrations exceeded the threshold values. The occurrence of periods of high concentration of particular pollen types were also noted. Risk of pollen allergy appeared the earliest at the beginning of February during Alnus and Corylus blooming. High concentrations of other woody plants were recorded from the last ten days of March to about 20 May, and of herbaceous plants from the first/last half of May-beginning of October.

Although lime trees have numerous benefits, they can pose a threat to allergy sufferers during the flowering period, as their pollen exhibits allergenic properties. This paper presents the results of 3 years of aerobiological research (2020–2022) carried out with the volumetric method in Lublin and Szczecin. A comparison of the pollen seasons in both cities revealed substantially higher concentrations of lime pollen in the air of Lublin than of Szczecin. In the individual years of the study, the maximum pollen concentrations were approximately 3-fold higher, and the annual pollen sum was about 2–3 times higher in Lublin than in Szczecin. Considerably higher lime pollen concentrations were recorded in both cities in 2020 than in the other years, which was probably associated with the 1.7–2.5 °C increase in the average temperature in April compared to the other two years. The maximum lime pollen concentrations were recorded during the last ten days of June or at the beginning of July in both Lublin and Szczecin. This period was associated with the greatest risk of pollen allergy development in sensitive subjects. The increased production of lime pollen in 2020 and in 2018–2019 with the increase in the mean temperature in April, reported in our previous study, may indicate a response of lime trees to the global warming phenomenon. Cumulative temperatures calculated for Tilia may serve as a basis for forecasting the beginning of the pollen season. [ABSTRACT FROM AUTHOR]

In vitro culture of Lilium longiflorum pollen grains was carried out to determine the role of manganese in pollen germination and pollen tube growth. Pollen germination was adversely affected by the presence of manganese (>10−8 M), whereas low concentrations (10−12–10−10 M) stimulated the process. Manganese caused morphological anomalies during tube growth, characterized by irregular pollen tube thickening and swollen tips. The main effect was the anomalous cell wall formation at the tip, in which the presence of several organelles reduced the number of secretory vesicles. A loose network of fibrillar material and spherical aggregates, mostly in the tip region, was detected, and this material was progressively loosened into the surrounding medium. As a response to potential toxicity, the excess manganese was isolated in vacuoles, which formed an internal barrier against penetration of manganese to the tip area. Elevated manganese concentrations might affect plant reproduction, resulting in anomalies in gamete development. Consequently, the loss in genetic diversity and decreased fruit set ultimately lower yield. [ABSTRACT FROM AUTHOR]

In terms of flowering ecology, Pulsatilla flowers are classified as "pollen flowers" producing inconsiderable amounts of nectar. The aim of this study was to assess the length of the flowering period in Pulsatilla slavica and P. vulgaris and to investigate the structure of the epidermis of the perianth and generative elements of their flowers. Special focus was placed on the structure of hairs and the distribution of stomata. The weight of nectar released by the flowers of the two Pulsatilla species and the content of sugars in the nectar was also evaluated. In SE Poland, both species flowered for similar periods between the second half of April and the first half of May. The flower life-span of both was determined to be 9-14 days. The lower part of each sepal was observed to be covered by long hairs having cellulose-pectin cell walls of varying thickness. Hairs present on the pistil style are thinner; they may provide some protection against cold and can play a role of a secondary pollen presenter for insects. The bowl-shaped structure of the perianth and the nature of the adaxial surface of the sepal epidermis may facilitate reflection of sunlight into the inner parts of the flower, which may contribute to an elevation of the intraflower temperature. This is particularly important for the functionality of the ovary. The surface of the hairs was seen to be covered by a cuticle ensuring water impermeability. Flowers are visited by honeybees, bumblebees, butterflies, and ants, for which nectar and pollen are the main attractants. Ants, which are regarded as illegitimate flower visitors, were found to cause damage to the androecium. The number of fruits produced in the flowers of both Pulsatilla species was lower than 50% of the number of pistils. [ABSTRACT FROM AUTHOR]

Pollen and nectar produced by flowers of species from the genus Salix are an important source of food for various insect groups in early spring. Most willows are entomophilous species; however, substantial amounts of airborne Salix pollen can be noted. The aim of the study was to evaluate the content of pollen of this taxon in the air of Lublin (central-east Poland) in 2001-2016 and to identify the period of its greatest availability to insects. In 2015, we compared the course of the Salix pollen season in Lublin (51°14'37" N; 22°32'25" E) and in the Roztoczański National Park (50°34'57" N; 23°04'24" E), Poland. We found that the date of the pollen season onset fluctuated greatly between March 16 and April 17. The greatest availability of Salix pollen to insects was noted from the end of the first 10-day-period of April to the first 10-day-period of May. The mean annual sum of airborne Salix pollen grains was 833. In Lublin, Salix pollen accounted for ca. 1.25% of the total airborne pollen content of different plant taxa. The investigations have demonstrated a 2-year cycle of Salix pollen abundance. The comparison of the pollen seasons in Lublin and in the Roztoczański National Park indicates that considerably greater amounts of pollen occur in the urban area than in the air of the Roztoczański National Park. [ABSTRACT FROM AUTHOR]

All lindens provide Apidae insects with nectar, pollen, and honeydew. Lindens are important melliferous trees in Poland. The first purpose of the study was to carry out phenological observations of the flowering in ten linden taxa. The second aim was to analyse the content of linden pollen grains in the air of Lublin. A correlation between the parameters of the pollen season and meteorological factors was also determined. This study was conducted in the city of Lublin located in the central-eastern part of Poland. The flowering phenophases were analysed, using the method developed by Łukasiewicz, during the growing seasons of 2012-2015. Aerobiological monitoring, which was based on the volumetric method, was carried out over the 2001-2014 time period. As shown in the study, the flowering period of all the analysed linden taxa lasted 7 weeks, on average, from June 7 to July 24. The average length of the flowering period of the investigated taxa and hybrids was in the range of 12-17 days. Their flowering periods overlapped. The atmospheric pollen season lasted, on average, from mid-June to the second 10-day period of July. The highest concentration of airborne pollen was noted at the end of June. The pollen season pattern was significantly affected by temperature and relative air humidity as well as by rainfall in May and June. The investigations indicate a 9-day acceleration of the pollen season, which may be associated with global warming. [ABSTRACT FROM AUTHOR]

Many plant species respond to the climate change reported in the recent decades, which is confirmed by the results of phenological and aerobiological investigations. This paper presents characteristics of the pollen seasons of Acer spp. revealed by aerobiological analyses performed with the volumetric method in Lublin, Poland in 2001-2015. Additionally, phenological observations of flowering of four Acer species, i.e., A. negundo, A. platanoides, A. campestre, and A. pseudoplatanus, were carried out in 2011-2012. The results indicate a slight upward trend in the annual totals of Acer pollen grains. Over the last 10 years, the annual totals of Acer pollen grains have increased in comparison to the previous 5-year period. Acceleration of the onset of pollen seasons and the dates of peak days was noted. The comparison of the pollen seasons and flowering phenology of four Acer species indicates that A. negundo and A. platanoides produce the highest concentrations of pollen grains, whereas the pollen of A. campestre and A. pseudoplatanus accounts for a significantly lower proportion of the pollen content in the air of Lublin. [ABSTRACT FROM AUTHOR]

The study compared the occurrence of airborne pollen of 7 arboreal taxa (Corylus, Alnus, Cupressaceae/Taxaceae, Populus, Fraxinus, Betula and Carpinus) during the period 2007-2009 from two sites in Lublin city, SE Poland. The sites differed in the character of building development and surrounding vegetation. Pollen monitoring was conducted by the volumetric method using two Hirst-type samplers. Daily and intradiurnal pollen counts were determined. For all the taxa, Spearman's test revealed statistically significant positive correlations between daily pollen fluctuations at two sites. Nevertheless, the Mann-Whitney U-test showed differences for Cupressaceae/Taxaceae, Fraxinus, Populus and Corylus between sites. The intradiurnal pattern of pollen concentration was characterized by high variation. Cupressaceae/Taxaceae and Populus, clearly differed in hourly pollen concentrations at both sites. Moreover, in the case of Betula and Alnus it was shown that a part of pollen recorded in Lublin can originate from long-distance transport. High pollen concentrations can be expected at different hours of the day. The lowest average pollen concentrations at both sites were found during morning hours at 5 and 6 a.m. Based on the obtained results, it can be concluded that data from a single pollen-sampling device are not representative of some taxa in the particular districts of the city. Average data obtained from at least two pollen samplers could provide optimum results. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agrobotanica is the property of Polish Botanical Society / Polskie Towarzystwo Botaniczne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agrobotanica is the property of Polish Botanical Society / Polskie Towarzystwo Botaniczne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of this study was to verify which parameters of the atmospheric pollen season can distinguish between pollen types, the ranges of parameter values that delineate classes of taxa, and finally which taxa are similar to others within the domain of these parameter ranges. Decision tree algorithms were applied and the best tree was chosen to describe the rules of pollen classification. The study material consisted of airborne pollen grains of the following eight taxa: Alnus, Betula, Carpinus, Corylus, Cupressaceae, Fraxinus, Populus and Ulmus. Research was conducted in Lublin in eastern Poland during 2001-2013. The following six atmospheric pollen season parameters were analyzed: season start and end, duration, maximum daily pollen concentration, date of maximum pollen concentration, and the Seasonal Pollen Index (SPI). Four algorithms were used in data analysis and the J4.8 algorithm was chosen as the best for taxa classification, date of the end of season and the SPI value belonging to characteristics that served most to discriminate between pollen types. Based on the classification tree, the following four groups of taxa were identified: (i) Ulmus; (ii) Corylus, Alnus, Populus; (iii) Betula; and (iv) Carpinus, Fraxinus, Cupressaceae. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agrobotanica is the property of Polish Botanical Society / Polskie Towarzystwo Botaniczne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Similarly to fungal spores and pollen grains, pteridophytic spores can cause allergies in humans. Pteridophyta spore concentrations in the air of Lublin, under the conditions of central-eastern Poland, were first studied over the period 2013-2014. The volumetric method was used in this study. The research showed that that spores of ferns belonging to the following genera: Asplenium, Athyrium, Blechnum, Botrychium, Cystopteris, Dryopteris, Matteuccia, Osmunda, Polypodium and Pteridium, occur in aeroplankton. Spores were recorded in low concentrations and they occurred in a dispersed pattern during the season. They were found to be absent on some days. Among the above-mentioned genera, Dryopteris and Athyrium showed the highest content of spores in aerosol. In both years of the study (2013 and 2014), similar annual spore counts were recorded, respectively 69 and 63. The most spores were identified in August. [ABSTRACT FROM AUTHOR]

In Europe Ambrosia is included in invasive species. Its pollen contains very strong allergens that can be the cause of pollinosis at the turn of summer and autumn. The aim of the present study was to compare Ambrosia pollen concentrations in the air of Lublin and Lviv and to analyse the effect of weather conditions on Ambrosia pollen content in the air. The study was carried out in 2011 and 2012. In Lublin the volumetric method was applied using a Lanzoni VPPS 2000 trap, whereas in Lviv the gravimetric method was applied using a Durham trap. To make the results comparable, the data obtained by the gravimetric method were properly counted and expressed as the number of pollen grains per 1 m³ of air. This research shows that the Ambrosia pollen season started about a month earlier in Lviv and lasted longer than in Lublin. In Lviv ragweed pollen was recorded from the beginning of July, while in Lublin from the second week of August. The pollen season in both cities ended on different days of October. The seasonal peaks in both years and the annual pollen count in 2011 were much higher in Lublin than in Lviv. In both cities air temperature was the most important meteorological factor affecting pollen concentrations. During the pollen season in Lublin, the wind was predominantly from NE and E directions, whereas in Lviv from N and SE. [ABSTRACT FROM AUTHOR]

The content of Aesculus pollen in aeroplankton of Lublin, located in central-eastern Poland, was studied during the period 2001-2012. The volumetric method was used for the study. The following parameters were determined: start, end, and duration of the pollen season, days of maximum concentration, and total annual pollen counts. Correlation coefficients were calculated between the start of the pollen season and meteorological parameters. The study showed that during the period 2007-2012 the onset of the Aesculus pollen season occurred on average 4 days earlier than in the years 2001-2006. The total annual pollen counts were in the range of 53-271, with an average number of 117. The average pollen counts did not differ significantly in the first and second year of a 6-year period of the study. The analysis of the correlation coefficients showed that there were significant positive correlations only between the season start date and minimum temperature of the first decade of May. The highest Aesculus pollen concentration occurred between 6 and 22 May. The flowers of A. hippocastanum demonstrate an ambophilous pollination strategy due to partial insect and wind pollination. [ABSTRACT FROM AUTHOR]

Ambrosia pollen contains strong allergens. Allergic reactions can also be caused by direct contact with the plant. The investigations of the dynamics of Ambrosia pollen seasons were conducted in Lublin (Poland) and Ivano-Frankivsk (Ukraine) in 2013–2015. The onset and end of the seasons, maximum concentrations, annual sums, and the number of days with an allergy risk were determined. Additionally, the types of trichomes present on different parts of Ambrosia artemisiifolia L. shoots were determined using light microscopy. Morphometric studies were carried out on trichomes sampled from staminate inflorescences. The maximum concentrations and annual sums of Ambrosia pollen were shown to be substantially higher in Ivano-Frankivsk than in Lublin. Similarly, the risk of allergies is higher in the study site in Ukraine. The study results indicate that the presence of Ambrosia pollen grains in Lublin may be associated with long-distance transport. The presence of non-glandular and glandular trichomes was found on the examined organs. The staminate inflorescences were covered by two types of non-glandular trichomes (short and long) and two types of glandular trichomes (linear and biseriate), whose secretory product can cause dermatitis in sensitive subjects upon contact with the plant. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that plants are a very good indicator of global environmental variations. The responses of many plant species to climate change are confirmed by aerobiological research. This paper presents an analysis of many parameters of pollen seasons in the Amaranthaceae family based on measurements of pollen concentrations in atmospheric air. Pollen samples were collected with the volumetric method at a sampling site in Lublin (Poland) in 2001–2019. The obtained data were verified using statistical analyses. Moreover, the presence of pollenkitt on the pollen grain surface was examined in fresh anthers using scanning electron and light microscopes, since there are some difficulties in identification of Amaranthaceae pollen grains deposited on microscopic slides in aerobiological analysis. The pollen season in Amaranthaceae began on average on June 23 and ended on October 5, i.e. it lasted 105 days. The peak value and annual pollen sum were characterized by the highest variability in the study years in comparison with other season characteristics. The annual pollen sum was in the range from 183 to 725. Maximum concentrations were most often recorded in the second half of August, which is associated with the greatest risk of development of pollen allergy symptoms in sensitive subjects during this period. The results obtained in the 19-year study revealed that the pollen seasons began 14 days earlier. Similarly, the end of the season was accelerated by 24 days. The response of these plants to climate change also include the reduced pollen production by representatives of this family, which was manifested by a decrease in the annual sum of daily airborne pollen concentrations, on average by 35%, and a reduction in the maximum pollen concentration, on average by more than 60%. We found that temperature in May and June had an effect on pollen release, and relative air humidity in May influenced pollen concentrations. We noted significant similarities in the pollen release rate during the last 8 years of the study. The scanning electron microscopy examinations showed that the pollen grain surface in the representative of this family was covered completely or partially with pollenkitt. Hence, the apertures characteristic for pollen in this family were poorly visible. The presence of pollenkitt on the surface of these polyaperturate pollen grains may play an important role in preventing water loss during pollen migration in the air. Our research has demonstrated the response of plants flowering in summer to climate change. The results not only have practical importance for public health in the aspect of allergy risk but can also help to assess environmental changes. [ABSTRACT FROM AUTHOR]

• Tilia pollen can cause pollen allergy in sensitive people. • In Poland, the risk of allergy to Tilia pollen occurs in June, July, and also in May. • The highest counts of Tilia pollen occur during the T. cordata flowering period. • The acceleration in the pollen season onset was almost 14 days during 18 years. • In 2018, the annual pollen sum increased by more than three times. Lindens belong to valued trees that are frequently planted in urban green areas. Nevertheless, during their flowering they can pose a risk to sensitive people in cities due to their allergenic pollen. This paper presents the results of a 3-year phenological study (2016–2018) and an 18-year aerobiological study (2001–2018) conducted in Lublin (Poland). The flowering phenology data for the following five species: T. americana , T. cordata , T. × euchlora , T. platyphyllos , and T. tomentosa , were compared with the data regarding Tilia pollen seasons. It was shown that the largest amounts of airborne Tilia pollen grains occur during the full flowering period of T. cordata and that the flowering sequence of the linden species studied is constant during the growing season: T. platyphyllos , T. americana , T. cordata , T. × euchlora , and T. tomentosa. We found pollen seasons to start earlier by 14 days and to be extended by 15 days. Throughout the study period, the annual Tilia pollen sum did not change significantly. However, in 2018 in which there was a significant increase in temperature above the average for the previous 17 years, flowering and pollen release distinctly accelerated, and the annual pollen sum increased more than three times compared to the average for the previous 17 years. In central-eastern Poland, the risk of pollen allergy due to the presence of Tilia pollen occurs in May, June, and July. We recorded the highest linden pollen concentrations in June. Due to the acceleration of flowering and pollen release in linden trees as a result of global warming, the incidence of pollen allergy in central Europe can be expected to become more intense already in the second half of May. Therefore, linden plantings in new urban green areas should be planned to be established at some distance from residential estates. [ABSTRACT FROM AUTHOR]