Variations in airborne pollen in central and south-western Spain in relation to the distribution of potential sources

The present study seeks to compare daily and hourly airborne pollen concentrations at eight different stations in Castilla-La Mancha (central Spain) and Extremadura (south-western Spain) and assess pollen distribution sources. Sampling stations were located 69–440 km apart in a straight line in Albacete, Toledo, Talavera de la Reina and Ciudad Real in Castilla-La Mancha, and in Badajoz, Plasencia, Santa Amalia and Zafra in Extremadura. Airborne pollen was collected using Hirst-type volumetric spore traps. Quercus was the most abundant pollen type at all stations except for Ciudad Real, where Olea pollen predominated. Comparisons of daily data between pairs of stations revealed statistically significant positive correlations in all cases for Poaceae and Olea. Comparisons of hourly data between stations indicated greater differences than daily data. Analysis of correlation coefficients and straight-line distances between stations revealed a strong negative correlation. Analysis of total airborne pollen data for the eight sampling stations suggests that airborne pollen concentrations decrease from west to east and from south to north, partly reflecting dominant wind patterns. A clear correlation was observed between airborne pollen concentrations and the surface area covered by olive crops in a 50 km radius around the sampling stations.     

Comparative study of seasonal and intradiurnal variation of airborne herbaceous pollen in urban and rural areas

The content of herbaceous pollen in the atmosphere depends on the vegetal cover, climate and the weather and geographical conditions. The aim of the study reported here was to compare aerobiological data obtained from pollen monitoring stations located at sites differing with respect to their flora and microclimate – i.e. a town and a rural area. A volumetric method was used for sampling. In each microscopic preparation 12 vertical strips corresponding with 2-h intervals were analysed. A 90% method was used to determine the pollen season. The results were statistically verified using the u test and the Kolmogorov-Smirnov, Spearman and Wilcoxon tests. Higher values of the Seasonal Pollen Index (SPI), higher daily average concentrations and higher peak values were recorded in the rural area. An analysis of intradiurnal variations of airborne pollen showed that apart from the Poaceae the number of pollen grains in the air began to increase earlier in the day in the rural area; in the case of Rumex and Ambrosia, the maximum values also appeared a few hours earlier. For all the taxa investigated, the analysis of correlation showed a significant association between the daily average concentrations at both sites. The weakest association occurred for Plantago lanceolata; for all other taxa, the determination coefficients (R ²) were high. The results of the Wilcoxon test showed that, despite the strong positive association between daily concentrations of the pollen types investigated, there were differences in mean pollen concentrations in the overlapping pollen season. Mean concentrations of Poaceae and Rumex airborne pollen were significantly higher in the rural area in both years, and those of Urtica and P. lanceolata were significantly higher only in 2002.     

Effect of meteorological parameters on Poaceae pollen in the atmosphere of Tetouan (NW Morocco)

Poaceae pollen is one of the most prevalent aeroallergens causing allergenic reactions. The aim of this study was to characterise the grass pollen season in Tetouan during the years 2008–2010, to analyse the effect of some meteorological parameters on the incidence of the airborne Poaceae pollen, and to establish forecasting variables for daily pollen concentrations. Aerobiological sampling was undertaken over three seasons using the volumetric method. The pollen season started in April and showed the highest pollen index in May and June, when the maximum temperature ranged from 23 to 27 °C, respectively. The annual pollen score recorded varied from year to year between 2,588 and 5,404. The main pollen season lasted 114–173 days, with peak days occurring mainly in May; the highest concentration reached 308 pollen grains/m³. Air temperature was the most important meteorological parameter and correlated positively to daily pollen concentration increase. An increase in relative humidity and precipitation was usually related to a decrease in airborne pollen content. External validation of the models performed using data from 2011 showed that Poaceae pollen concentration can be highly predicted (64.2–78.6 %) from the maximum temperature, its mean concentration for the same day in other years, and its concentration recorded on the previous day. Sensitive patients suffering allergy to Poaceae pollen are at moderate to highest risk of manifesting allergic symptoms to grass pollen over 33–42 days. The results obtained provide new information on the quantitative contribution of the Poaceae pollen to the airborne pollen of Tetouan and on its temporal distribution. Airborne pollen can be surveyed and forecast in order to warn the atopic population.     

Poaceae pollen in the atmosphere of Tetouan (NW Morocco): effect of meteorological parameters and forecast of daily pollen concentration

The Poaceae pollen season has been characterized in Tetouan during a 7-year period, and the effect of weather conditions on daily concentrations was examined. The forecast models were produced using a stepwise multiple regression analyses. Firstly, three models were constructed to predict daily Poaceae pollen concentrations during the main pollen season, as well as the pre-peak and post-peak periods with data from 2008 to 2012 and tested on data from 2013 and 2014. Secondly, the regression models using leave-one-out cross-validation were produced with data obtained during 2008–2014 taking into account meteorological parameters and mean pollen concentrations of the same day in other years. The duration of the season ranged from 70 days in 2009 to 158 days in 2012. The highest amount of Poaceae pollen was detected in spring and the first fortnight of July. The annual sum of airborne Poaceae pollen concentrations varied between 2100 and 6251. The peak of anthesis was recorded in May in six of the other years studied. The regression models accounted for 36.3–85.7% of variance in daily Poaceae pollen concentrations. The models fitted best when the mean pollen concentration of the same day in other years was added to meteorological variables, and explained 78.4–85.7% of variance of the daily pollen changes. When the year 2014 was used for validating the models, the lowest root-mean-square errors values were found between the observed and estimated data (around 13). The reasonable predictor variables were the mean pollen concentration of the same day in other years, mean temperature, precipitations, and maximum relative humidity.     

Aeropalynological spectrum of Hatay,Turkey, the eastern coast of the Mediterranean Sea

An aeropalynological study during the years 2014–2015 was performed in Hatay, which is a unique sociocultural and phytogeographical area located on the border of Turkey and Syria on the eastern coast of the Mediterranean. The sampling was performed by a Hirst-type volumetric sampler (Lanzoni VPPS 2000), and pollen grains of 54 taxa were identified, of which 83.21% of the annual sum belonged to woody taxa. The highest pollen concentration was recorded in February, of which a large amount came from the Cupressaceae/Taxaceae families. The diversity of the pollen reflected the vegetation of the area and plantations of the city center, but pollen grains from Euro-Siberian elements specific to Mount Amanos could not be recorded. Pollen types found at more than 3% of the annual pollen index and considered dominant pollen types were as follows: Cupressaceae/Taxaceae (50.86%), Olea europaea (12.67%), Moraceae (7.20%), Poaceae (5.99%), Quercus (5.35%), Urticaceae (3.79%) and Pinus (3.70%); almost all dominant pollen types in the city atmosphere were previously stated to be allergic. The main pollen season starting dates of common pollen types found were one or two weeks earlier than those of the surroundings. Many statistically significant correlations were found between daily pollen concentrations and daily meteorological parameters, e.g., Cupressaceae/Taxaceae Poaceae and Urticaceae pollen correlated negatively with mean temperature in both years, and in the hindermost two families daily pollen amounts significantly correlated with wind speed in the second year. Daily Olea europaea pollen concentration showed a significant negative correlation with the amount of total daily rainfall in the second year.     

Dynamics and behaviour of airborne Quercus pollen in central Iberian Peninsula

Quercus pollen is one of the most abundant pollen types in the atmosphere of central Iberian Peninsula (Spain), as a consequence of the extensive representation of well-preserved forests and shrub communities dominated by species of the genus Quercus in this area. This paper analysed key features of the Quercus pollination season in the central Iberian Peninsula and the influence of weather-related variables on airborne Quercus pollen concentration through statistical techniques of correlation analysis and the use of a decision tree model for predicting pollen concentrations. Quercus species are very common in Spain and Portugal, dominating a number of ecosystems including Mediterranean forests. This gives rise to very high airborne Quercus pollen concentrations, particularly in spring. Sampling was carried out over a 6-year period using a Hirst volumetric sampler, and the sampling procedure established by the Spanish Aerobiology Network. Results show that between 92 and 98.5 % of total annual airborne Quercus pollen was recorded in the April–June period. Annual pollen index were high in all study years, averaging 12,344 grains, but it should be highlighted that pollen production was highly variable between years. Correlations between mean daily Quercus pollen concentration and weather-related variables showed that in the pre-peak period, a significant positive correlation was observed with the mean daily temperature and the hours of sunshine and a negative correlation was observed with the humidity and the rainfall. In the post-peak period, a significant negative correlation was found with the mean daily temperature and the hours of sunshine. The predictions obtained in the decision tree model showed a moderate significant correlation (r = 0.42) with the daily Quercus pollen concentration predicted and the one observed. Temperature is the most influential variable in the release of Quercus pollen.     

Exploring the spatio-temporal relationship between two key aeroallergens and meteorological variables in the United Kingdom

Constructing accurate predictive models for grass and birch pollen in the air, the two most important aeroallergens, for areas with variable climate conditions such as the United Kingdom, require better understanding of the relationships between pollen count in the air and meteorological variables. Variations in daily birch and grass pollen counts and their relationship with daily meteorological variables were investigated for nine pollen monitoring sites for the period 2000–2010 in the United Kingdom. An active pollen count sampling method was employed at each of the monitoring stations to sample pollen from the atmosphere. The mechanism of this method is based on the volumetric spore traps of Hirst design (Hirst in Ann Appl Biol 39(2):257–265, 1952). The pollen season (start date, finish date) for grass and birch were determined using a first derivative method. Meteorological variables such as daily rainfall; maximum, minimum and average temperatures; cumulative sum of Sunshine duration; wind speed; and relative humidity were related to the grass and birch pollen counts for the pre-peak, post peak and the entire pollen season. The meteorological variables were correlated with the pollen count data for the following temporal supports: same-day, 1-day prior, 1-day mean prior, 3-day mean prior, 7-day mean prior. The direction of influence (positive/negative) of meteorological variables on pollen count varied for birch and grass, and also varied when the pollen season was treated as a whole season, or was segmented into the pre-peak and post-peak seasons. Maximum temperature, sunshine duration and rainfall were the most important variables influencing the count of grass pollen in the atmosphere. Both maximum temperature (pre-peak) and sunshine produced a strong positive correlation, and rain produced a strong negative correlation with grass pollen count in the air. Similarly, average temperature, wind speed and rainfall were the most important variables influencing the count of birch pollen in the air. Both wind speed and rain produced a negative correlation with birch pollen count in the air and average temperature produced a positive correlation.     

Quantifying the relationship between airborne pollen and vegetation in the urban environment

The goal of this study was to quantitatively assess the relationship linking vegetation and airborne pollen. For this, we established six sampling stations in the city of Thessaloniki, Greece. Once every week for 2 years, we recorded airborne pollen in them, at breast height, by use of a portable volumetric sampler. We also made a detailed analysis of the vegetation in each station by counting all existing individuals of the woody species contributing pollen to the air, in five zones of increasing size, from 4 to 40 ha. We found the local vegetation to be the driver of the spatial variation of pollen in the air of the city. Even at very neighbouring stations, only 500 m apart, considerable differences in vegetation composition were expressed in the pollen spectrum. We modelled the pollen concentration of each pollen taxon as a function of the abundance of the woody species corresponding to that taxon by use of a Generalized Linear Model. The relationship was significant for the five most abundantly represented taxa in the pollen spectrum of the city. It is estimated that every additional individual of Cupressaceae, Pinaceae, Platanus, Ulmus and Olea increases pollen in the air by approximately 0.7, 0.2, 2, 6 and 5%, respectively. Whether the relationships detected for the above pollen taxa hold outside the domain for which we have data, as well as under different environmental conditions and/or with different assemblages of species representing them are issues to be explored in the future.     

Designing new automatically generated pollen calendars for the public in Switzerland

Pollen calendars are one of the most comprehensible means to inform allergy sufferers or medical professionals about the mean presence of allergenic pollen during the course of the year. They have been produced with a variety of methods and were distributed with great success since the beginning of pollen monitoring. Current technologies, longer data series and changing user demands allow to develop new calculation methods. For designing the new pollen calendars of Switzerland, the following requirements were formulated: The pollen load levels in the calendars should correspond to the levels used in pollen forecasts. A pollen load level in the calendar should show the time window in which it potentially occurs. Further requirements were an automatic generation of the calendars, a regular update and the possibility to provide calendars for single stations, regions or specific pollen species. The data analysis is based on mean daily pollen concentrations of the last 20 years of all 14 pollen-monitoring stations in Switzerland for the 15 pollen types most relevant for allergies. For each day of the year, the 90% quantile of the daily pollen concentrations is determined in a moving 9-day time window over 20 years of data. The calculated concentrations are converted afterward into a pollen load level. The new method is flexible because various parameters can be selected freely: the reference period, the size of the moving time window, the quantile value and the thresholds for pollen load levels. Adjusting these parameters, also pollen calendars for fewer than 20 years can be calculated. However, a sensitivity analysis showed that a reference period of 20 years provides much more stable pollen calendars than shorter reference periods.     

An aeropalynological survey in the city of Van,a high altitudinal region,East Anatolia-Turkey

Pollen concentrations in the atmosphere of Van city has been monitored for two consecutive years (2010–2011). This was the first detailed aeropalynological study for the elevated East Anatolia Region of Turkey. The sampling was performed by Hirst-type volumetric sampler, and pollen grains of 35 taxa were identified. The main pollen producers of the pollen flora were recorded as: Poaceae (20.94 %), Cupressaceae (10.53 %), Fraxinus (8.56 %), Chenopodiaceae/Amaranthaceae (7.77 %), Populus (7.75 %), Quercus (6.70 %), Platanus (6.68 %), Morus (5.57 %), Plantago (3.03 %). The pollen spectrum reflected the floristic diversity of the region, and the highest pollen concentration was recorded in April. There were a great percentage of allergenic taxa found in the city atmosphere, otherwise many of them scored under threshold values for risk of pollinosis. Statistical analyses were performed for correlating daily pollen concentrations of dominated pollen types concurrent with the data of meteorological parameters in MPS periods and number of significant correlations found. In addition, comparing 2-year data in terms of pollen concentrations and meteorological factors in MPS durations, many variables were found explanatory and concordant with the data. MPS starting dates of many plant taxa were found nearly a month later compared with western sites and lower altitudes of the country as well as Mediterranean countries; this case is mostly thought the ecological factors of the study area which directly affects the plant growth about the timing.     

Pollen spectrum in Northern Tunis,Tunisia

This study has been focused on airborne pollen concentration in Northern Tunis. Pollen has been detected by a volumetric Hirst-type spore trap. This suction sampler was placed for two hydrologic years in the area of Mornag, northeastof Tunisia (36°40N; 10°17E). Fifty-two taxa were identified with heterogeneous daily pollen concentrations and a dominance of anemophilous plants. The main pollen types detected in the atmosphere were Olea europaea (38.7 and 20.75%), Cupressus (33.57 and 55.4%), Urticaceae (9.22 and 12.24%), Poaceae (3.55 and 3.32%), Mercurialis annua (2.96 and 1.6%) and Amaranthaceae (2.49 and 1.55%). The monthly pollen spectrum indicated a seasonal periodicity of airborne pollen with the main pollen season during spring. Two pollen seasons have been observed during these hydrologic years, due to both Cupressus and Amaranthaceae airborne pollen is represented during winter or spring, and also during autumn and late summer, respectively. Other pollen types represent a long pollen season, i.e., Urticaceae, starting in autumn and following until late spring. Daily pollen concentration showed a different behavior during the flowering season between both years, observing differences related to pollen index. Correlation between daily pollen concentrations of the dominant taxa showed a positive and significant correlation between airborne pollen concentrations of spring-pollinated taxa and mean temperature, but negative with maximum temperature, humidity and rainfall. In the case of minimum temperature, a different response, positive for trees and negative for herbaceous plants, has been observed.     

A 3-year airborne pollen and fungal spores record in San Carlos de Bariloche, Patagonia, Argentina

Airborne pollen in San Carlos de Bariloche was sampled from September to March 2001–2004 with a Hirst-type volumetric spore trap placed at a height of 15 m in a city extending from the humid forests, through the mesic forests, to the steppe. The total amount of pollen recorded varied widely from year to year. The pollen index was 4,395 in the sampling period 2001/2002; 9,055 in 2002/2003 and 2,756 in 2003/2004. The main pollen period extended from October to January. In October, pollen concentration was the highest. Sixty-six pollen types were identified. Cupressaceae and Nothofagus were the major contributors. Betula, Prunus, Pinus and Populus, the most abundant ornamental taxa in the city, also contributed to the pollen record. Pollen of Maytenus and Lomatia was representative of the mesic forest, while pollen in the lower layers of the humid forest was present in trace amounts. Cupressaceae, Nothofagus and Betula prevailed during spring (September–December), and Plantago, Rumex and Poaceae during summer (December–March). The association of daily pollen concentration and meteorological variables, temperature (mean, maximum, minimum), dew point, rainfall and wind speed, was significant. Correlations showed to be negative, with the exception of that to wind speed. The total sum of fungi spores increased from 1,771 in 2001/2002; through 8,441 in 2002/2003 to 13,782 in 2003/2004. Relative concentration rose to 29%, 48% and 84% of the total number of pollen and fungal spores recorded during each sampling period.     

Spring airborne pollen data in two sites in Trentino (Northern Italy): a comparison with meteorological data

In this paper airborne pollen concentration is compared to meteorological data of Trento and S. Michele all’Adige, two sites in the Adige Valley, in Trentino (North Italy). Pollen ofCorylus, Alnus, Betula andOstrya, four winter-spring flowering plants are considered. Pollen sampling was carried out in 1996 by volumetric Hirst-type samplers. For all pollen types considered, maximum pollen concentration coincided in both stations and there was a good overlap of the main pollen season length; the pollen curves of S. Michele a/A and Trento showed a highly positive correlation. The daily airborne pollen concentrations, defined as the number of pollen grains per cubic meter of air (P/m³), were compared to daily meteorological data: minimum and maximum air temperature (°C), average relative humidity (%), precipitation (mm), global incident radiation (cal/cm²), average wind direction (°) and wind speed (m/s). A highly positive correlation was found forCorylus and maximum temperature in both monitoring stations.Betula was positively, whereasOstrya was negatively correlated to relative humidity. With this first analytical approach sharp differences in the atmospheric pollen presence between the stations located at Trento and S. Michele all’Adige were not found.     

A 2-year aeropalynological survey of allergenic pollen in the atmosphere of Kastamonu, Turkey

Knowledge of airborne pollen concentrations and the weather conditions influencing them is important for air quality forecasters, allergists and allergy sufferers. For this reason, a 7-day recording volumetric spore trap of the Hirst design was used for pollen monitoring between January 2006 and December 2007 in Kastamonu, Turkey. A total of 293,427 pollen grains belonging to 51 taxa were recorded during the study period. In the 2?years of study, the period March–August was identified as the main pollination season for Kastamonu. The highest monthly pollen counts were observed in May in both years. Six taxa made up 86.5% of the total amount of pollen recorded in the atmosphere of Kastamonu. These were as follows: Pinaceae (42.9%), Cupressaceae (20.6%), Poaceae (9.7%), Quercus (5.5%) Betula (5.3%) and Carpinus (2.6%). Four of these are considered to be highly allergenic (Betula, Carpinus, Cupressaceae and Poaceae). There were also a greater percentage of highly allergenic taxa found within the city, including Betula pendula that is not part of the local flora. This shows that through urban planting, the public and municipalities can unconsciously create a high risk for allergy sufferers. Daily average pollen counts from the six most frequently recorded pollen types were entered into Spearman’s correlation analysis with meteorological data. Mean daily temperature, relative humidity, daily rainfall and wind speed were found to significantly (p?<?0.05) affect atmospheric pollen concentrations, but the relationships between pollen concentrations and meteorological variables can vary and so there is a need for more local studies of this nature.     

Twenty years of aerobiological monitoring in Trentino (Italy): assessment and evaluation of airborne pollen variability

The aim of the study is to report a reliable airborne pollen spectrum composition and seasonal timings for the monitored area as a basis for allergy management and to ascertain possible modifications through the detection of trends during the 20-year time series (1989–2008). Pollen was collected at San Michele all’Adige (Trento, Italy) by means of a Hirst-type spore trap. Sampling and counting of airborne pollen grains were carried out according to a national standard. Pollen concentration data for the period were processed in order to characterize the main pollen seasons for a subset of taxa, selected on the basis of their allergenicity and local representativeness. Variations in the pollen data over the years surveyed were analyzed using non-parametric tests. The results showed the presence of 63 pollen taxa, 40 of which belonged to tree and shrub species and 23 to herbaceous species. The local pollen spectrum was characterized by the presence of highly allergenic taxa, such as Urticaceae, Graminaceae, Ostrya sp., and Cupressaceae, in terms of percentage contribution as well as mean daily pollen count or peak values over the years surveyed. A significant upward trend was observed for daily mean pollen amount, mainly due to pollen from woody species and probably ascribable to a temperature-driven increase in pollen production. Evaluation of the results presented will form the basis of further research focussed on the climate change-related causes of modifications to vegetational dynamics as well as on the phenology of flowering and on pollen production.     

Seasonal distribution of airborne pollen in Manila,Philippines, and the effect of meteorological factors to its daily concentrations

Pollen-related allergic diseases are a growing health problem. Thus, information on prevalence of airborne pollen may serve as guide for clinicians to accurately manage allergic diseases. In this study, an aeropalynological survey was conducted from November 2013 to October 2014 in Manila, Philippines, to determine the seasonal distribution of the most prevalent airborne pollen and correlate the influence of meteorological factors on their daily concentrations. A volumetric pollen trap was placed on a rooftop, 21 m above ground level. A total of 5677 pollen grains from 18 pollen types were identified, of which Urticaceae, Cannabaceae, Poaceae and Moraceae were the most prevalent. Other pollen types observed that represented 1 % of the total pollen concentration, in descending order, were Terminalia catappa, Myrtaceae, Muntingia calabura, Verbenaceae, Amaranthaceae, Cyperaceae, Caricaceae and Mimosa sp. Of the total airborne pollen, 87 % were obtained during the dry season (November–May). Pollen concentrations peaked (55 %) during the summer months (March–May), indicating a positive correlation (p < 0.01) between pollen concentration and temperature (maximum and mean). Alternatively, only 13 % of the pollen concentrations were obtained during the wet season (June–October). It was observed that pollen concentrations were negatively correlated (p < 0.01) with rainfall and humidity. As the pollen collection was done for one sampling year, only an approximation of the daily concentration of the pollen types was identified and correlated with meteorological factors. Further data collection is required to generate an accurate pollen calendar for use in allergy studies.     

A systematic review of the effects of temperature and precipitation on pollen concentrations and season timing,and implications for human health

Climate and weather directly impact plant phenology, affecting airborne pollen. The objective of this systematic review is to examine the impacts of meteorological variables on airborne pollen concentrations and pollen season timing. Using PRISMA methodology, we reviewed literature that assessed whether there was a relationship between local temperature and precipitation and measured airborne pollen. The search strategy included terms related to pollen, trends or measurements, and season timing. For inclusion, studies must have conducted a correlation analysis of at least 5 years of airborne pollen data to local meteorological data and report quantitative results. Data from peer-reviewed articles were extracted on the correlations between seven pollen indicators (main pollen season start date, end date, peak date, and length, annual pollen integral, average daily pollen concentration, and peak pollen concentration), and two meteorological variables (temperature and precipitation). Ninety-three articles were included in the analysis out of 9,679 articles screened. Overall, warmer temperatures correlated with earlier and longer pollen seasons and higher pollen concentrations. Precipitation had varying effects on pollen concentration and pollen season timing indicators. Increased precipitation may have a short-term effect causing low pollen concentrations potentially due to “wash out” effect. Long-term effects of precipitation varied for trees and weeds and had a positive correlation with grass pollen levels. With increases in temperature due to climate change, pollen seasons for some taxa in some regions may start earlier, last longer, and be more intense, which may be associated with adverse health impacts, as pollen exposure has well-known health effects in sensitized individuals.

     

Annual pollen spectrum variations in the air of Bratislava (Slovakia): years 2002–2009

Pollen grains in the atmosphere of Bratislava were quantitatively and qualitatively analysed during an 8-year period (2002–2009) using a Burkard volumetric pollen trap. The mean annual total pollen grain count recorded during this period was 36,608, belonging to 34 higher plant taxa (22 trees and/or shrubs and 12 herbaceous species). The maximum annual total pollen grain count (50,563) was recorded in 2003 and the minimum (14,172) in 2009. The taxa contributing the highest concentration of pollen grains were Betula, Urticaceae, Cupressaceae-Taxaceae, Populus, Pinus, Poaceae and Ambrosia. During the study period, there was a remarkable increase in the number of pollen grains from February to April, with the highest daily mean pollen counts recorded in April. Total pollen concentration began to decrease markedly in May, but there was a second increase between July and August, followed by a decrease in September. The timing and length of the pollen seasons varied. Betula and Poaceae showed a rather constant 2-year fluctuating rhythm. The relationships between airborne pollen concentration and meteorological variables were assessed. Based on these results, the first pollen calendar in Slovakia has been constructed for the area of Bratislava, which provides a great deal of useful and important information.     

Threat of allergenic airborne grass pollen in Szczecin,NW Poland: the dynamics of pollen seasons,effect of meteorological variables and air pollution

The dynamics of Poaceae pollen season, in particularly that of the Secale genus, in Szczecin (western Poland) 2004–2008 was analysed to establish a relationship between the meteorological variables, air pollution and the pollen count of the taxa studied. Consecutive phases during the pollen season were defined for each taxon (1, 2.5, 5, 25, 50, 75, 95, 97.5, 99% of annual total), and duration of the season was determined using the 98% method. On the basis of this analysis, the temporary differences in the dynamics of the seasons were most evident for Secale in 2005 and 2006 with the longest main pollen season (90% total pollen). The pollen season of Poaceae started the earliest in 2007, when thermal conditions were the most favourable. Correlation analysis with meteorological factors demonstrated that the relative humidity, mean and maximum air temperature, and rainfall were the factors influencing the average daily pollen concentrations in the atmosphere; also, the presence of air pollutants such as ozone, PM₁₀ and SO₂ was statistically related to the pollen count in the air. However, multiple regression models explained little part of the total variance. Atmospheric pollution induces aggravation of symptoms of grass pollen allergy.     

Meteorological factors affecting daily urticaceae pollen counts in southwest Spain

The influence of meteorological factors on daily Urticaceae pollen counts were studied in Córdoba (southwest Spain) in 1996 and 1997. The daily Urticaceae pollen concentrations were obtained by using a Hirst-type volumetric sampler, and meteorological data were obtained from the Córdoba airport, located near the sampling site. The highest correlation between pollen concentration and meteorological parameters was obtained during non-rainy seasons. Temperature was found to be the most important meteorological parameter influencing pollen counts in spring, as temperature is the main reason for the increase of pollen concentration in the atmosphere. In autumn, humidity was another important parameter influencing pollen counts. Rain, however, did not appear to be significant. The influence of the pollen concentration of the 2 previous days and the pollen concentration of the previous day has been studied. During periods with low precipitation, the pollen concentration of the previous day was a useful predictor of Urticaceae pollen concentrations for the following day. Received: 4 January 1999 / Revised: 26 July 1999 / Accepted: 6 September 1999