Daily Pollen Research Articles

A method for producing airborne pollen source inventories: An example of Ambrosia (ragweed) on the Pannonian Plain

We present here a simple methodology for calculating species inventories for allergenic pollen that can be used by atmospheric transport models. Ragweed ( Ambrosia) species distribution or infection level on the Pannonian Plain has been used as an example of how the methodology can be used. The Pannonian Plain is one of the three main regions in Europe recognized as being polluted by Ambrosia. The methodology relies on spatial variations in annual Ambrosia pollen counts, knowledge on ragweed ecology and detailed land cover information. The results of this analysis showed that some of the highest mean annual ragweed pollen concentrations were witnessed around Kecskemét in central Hungary and Novi Sad in northern Serbia. These areas are also the areas with the highest density of Ambrosia habitats. The resulting inventory can be entered into atmospheric transport models in combination with other components such as a phenological model and a model for daily pollen release, in order to simulate the movement of ragweed pollen from the Pannonian Plain. The methodology is likely to be generally applicable for creating inventories of species distribution of allergenic plants. The main requirement is availability of: detailed land cover information; pollen indexes; a list of the most important habitats; and a region of interest that is mainly influenced by local sources.

Relationship between olive flowering and latitude in two Mediterranean countries (Italy and Tunisia)

In phenological studies, the plant developments are analysed considering their relationships with seasonal meteorological conditions; moreover, the influences of geographical features on biological responses have to be also considered. Different studies analysed the influence of latitude on phenological phases to investigate the possible different magnitude of biological response. In our experience, this type of geographic evaluation was conducted considering one of the more important plant species of Mediterranean shrub, the olive (Olea europaea L.) in fifteen olive monitoring stations, four located in Tunisia and eleven in Italy, from the southern Zarzis area at 33° to the northern Perugia area at 43° of latitude. The olive flowering phenomenon was studied, utilising an aerobiological monitoring method through appropriate pollen traps located inside olive groves from 1999 to 2008. The olive monitored pollen grains were recognised and evaluated to obtain daily pollen concentrations to define the flowering dates in the different study areas. The biometeorological statistical analysis showed the 7°C threshold temperature and the single triangle method for growing degree days (GDD) yearly computing as the better ones in comparison to others. Moreover, the regression analysis between the dates of full flowering and the GDD amounts at the different monitoring latitudes permitted us to evidence the biological response of olive species in geographic regions with different climate patterns. The specific biological response at different latitude was investigated, the slope results, as flowering days per heat amounts, evidenced that olive species behaviours are very constant in consequence to similar meteorological conditions independently to latitude variations. Averagely, the relationships between plant’s phenology, temperature trends and geographical features are very close, even if the yearly mesoscale meteorological variations force to consider, year by year, phenological advances or delays as local events.

Correlation between eosinophilic oesophagitis and aeroallergens

Aeroallergens have been implicated in the pathogenesis of eosinophilic oesophagitis. To determine whether a seasonal variation exists in the diagnoses of eosinophilic oesophagitis and whether there is a correlation with seasonal pollen count. A retrospective review was performed from January 2006 to November 2008 to identify eosinophilic oesophagitis patients. Cases were classified by endoscopic date. Daily pollen counts for grass, trees and weeds were obtained from a certified counting station. Per cent of eosinophilic oesophagitis cases were collated seasonally and compared with mean pollen counts for grass, trees and weeds during the same time period. A total of 127 eosinophilic oesophagitis cases were identified (median age 41, range 19-92 years, 84% men). The highest percentage of cases (33.0%; Binomial P = 0.022) was diagnosed in the spring, while the least percentage (16%; Binomial P = 0.0.010) occurred in the winter. There was a significant association between per cent eosinophilic oesophagitis cases diagnosed seasonally and mean grass pollen count (r(s) = 1.000, P < 0.01), but not with trees (r(s) = 0.400, P = 0.600) or weeds (r(s) = 0.800, P = 0.200). A seasonal variation was seen in the diagnosis of eosinophilic oesophagitis which correlated with pollen counts. These findings have important implications regarding the pathogenesis of eosinophilic oesophagitis, suggesting a potential role for aeroallergens.

Description of the main Poaceae pollen season using bi-Gaussian curves, and forecasting methods for the start and peak dates for this type of season in Rzeszów and Ostrowiec Św. (SE Poland)

Grasses characteristically produce a huge amount of small pollen grains, which pose a risk to allergy sufferers. In many aerobiological studies, great variations in the behaviour of the grass pollen season are stressed. We state that in Rzeszów and Ostrowiec Sw. there is some regularity in the pattern of the main grass pollen seasons, which is clearly double-peaked. The aim of our work was to elaborate the algorithm which defines the main grass pollen season. Next, the null hypothesis was tested about the lack of difference between daily pollen concentrations and meteorological parameters. Grass pollen seasons were defined using the method of fitting two bell curves. The estimated grass pollen season is characterised by two periods of high or relatively high concentrations, separated by a period of low concentration. In order to investigate the time dependence of the correlation between pollen concentration and the weather parameters, the Gaussian-weighted correlation coefficient has been calculated. Maximum temperature, mean temperature and sunshine positively correlated with pollen concentrations, but relative air humidity and rainfall on the previous day had a negative effect. The temperatures of the second and third ten-day periods of April were the best independent variables for forecasting the beginning and peak dates of the main pollen seasons. An analysis of the results shows that the pattern of successive flowering in grass species and meadow cutting dates appear to be the factors which cause the characteristic bimodal behaviour of the grass pollen season.

Development of a novel real-time pollen-sorting counter using species-specific pollen autofluorescence

We developed a novel flow particle analyzer that automatically classifies airborne pollen grains. The design of the particle counter (model KP-1000) is based on that of a flow cytometer, applied to the measurement of airborne particles. The counter classifies pollen species by simultaneously detecting both scattered light and the characteristic fluorescence excited by ultraviolet light in the flow cell. We observed airborne pollen using KP-1000 pollen counters and Durham samplers to compare their performance at three study sites in Japan during the spring pollen season. The pollen counter followed the variation in pollen concentrations, and its daily pollen counts were significantly correlated with the results of the Durham sampling method at all study sites. Although the counter over- or under-counted 2 target pollen species (Cryptomeria japonica and Chamaecyparis obtusa) when they coexisted, a data correction based on the Durham sampling results improved the accuracy of pollen classification of the counter. Our results indicate that the new pollen counter has a strong potential for counting and identifying airborne pollen grains in real time, and it requires further improvement, field trials, and tests with other common airborne pollen grains.

Yield modelling in a Mediterranean species utilizing cause–effect relationships between temperature forcing and biological processes

Crop yield forecasting has progressed clearly in the past years, mainly due to the growing demand for modelling. In the present research, considering the Mediterranean vocation for the olive cultivation, olive yield forecasting modelling was analysed, to understand the principal relationships between olive tree production and climate features in a large southern Italy area. The simulation of olive yield has practical application in different price formation activities: in management of cropping systems, formation of stocks, commercialization, making of agricultural policies and zoning. Both meteorological and biological variables were considered, pollen indexes were constructed from daily pollen concentrations evaluated by use of aerobiological methodology. The monitored pollen quantities should be considered as a Proxy variable of the olive orchards located around the volumetric pollen traps, even if the final harvest could be highly dependent on local summer meteorological conditions. The model carried out by use of Panel data analysis has demonstrated a great interpretative capacity, considering contemporary meteorological and biological variables (pollen monitored with volumetric traps). The aggregation of historical data (1999–2008) with cross-section data (10 different pollen monitoring stations) permitted to investigate the variability information related to temporal and geographical dimensions. The entire volume of pollen grains emitted during flowering was redundant to investigate the future fruit formation while the specific and concentrated mass of pollen grains during the days before full flowering was related positively with the final production. The statistical technique utilized permitted to obtain interpretative results common to different geographical areas and not limited by local meteorological conditions.

Benford’s law applied to aerobiological data and its potential as a quality control tool

Benford’s phenomenological law gives the expected frequencies of the first significant digits of any given series of numbers. According to this law, the frequency of 1 is higher than that of 2; this in turn appears more often 3, and so on. Similarly, Benford’s law can also be applied to the first two significant digits (i.e., from 10 to 99), and so on. Here, we show that gross data sets of daily pollen counts from three aerobiological stations (located in European cities with different features regarding vegetation and climatology) fit Benford’s law for the first significant digits, but this is not always true for the data transformed by a correction factor used in aerobiological studies. That is to say, the biases introduced by rounding and lower and upper built-in limits in pollen counts are detected by Benford’s law analysis. The analysis of the first two significant digits from transformed data is better explained by a Power law than Benford’s law. We propose that Benford’s law could be used as a quality control tool for numerical aerobiological data sets.

Pollen Loads and Allergic Rhinitis in Darwin, Australia: A Potential Health Outcome of the Grass-Fire Cycle

Although the prevalence of asthma and allergic rhinitis has been increasing in tropical regions, little is known about the allergenicity of pollens from tropical plant families or the importance of ongoing environmental changes. We investigated associations between daily average pollen counts of several tropical plant families and sales of medications for the treatment of allergic rhinitis in Darwin, Australia-a tropical setting in which grass abundance has increased due to increased fire frequencies and the introduction of African pasture grasses. Daily pollen counts with detailed identification of plant species were undertaken in conjunction with a weekly survey of flowering plant species from April 2004 to November 2005. Five pharmacies provided daily sales data of selected medications commonly used to treat allergic rhinitis. We used generalized linear modeling to examine outcomes. All analyses accounted for the potential confounding effects of time trends, holidays, respiratory viral illnesses, meteorological conditions, and air pollution. The peak total pollen count was 94 grains/m(3). Despite the low levels of Poaceae (grass) pollen (maximum daily count, 24 grains/m(3)), there was a clear association with daily sales of anti-allergic medications greatest at a lag of 1 day. Sales increased by 5% with an interquartile range rise (3 grain/m(3)) in Poaceae pollen (5.07%, 95%CI 1.04%, 9.25%). No associations were observed with pollen from other plant families. Although further testing is required, we suggest that an overlooked aspect of the "grass-fire cycle" that is degrading many tropical landscapes, could be an increase in the prevalence of allergic rhinitis.

Comparison of airborne herb pollen types in Córdoba (Southwestern Spain) and Poznan (Western Poland)

This study sought to compare airborne pollen counts for a number of common herbaceous species (Plantago, Chenopodiaceae–Amaranthaceae, Rumex, and Urticaceae) in two cities with differing weather conditions, Cordoba (Southwestern Spain) and Poznan (Western Poland). Pollen seasons for these species were studied from 1995 to 2005. Aerobiological sampling was performed using a Hirst type 7-day spore trap, in accordance with the procedure developed by the European Aerobiology Network. A Spearman correlation test was used to test for correlations between meteorological parameters and daily airborne pollen counts. The Spearman correlation test and the Wilcoxon signed ranks test were also used to compare mean daily pollen counts for the two study sites. In Cordoba, the pollen season generally started around two months earlier than in Poznan, and also lasted longer. These findings were attributed to the presence of a larger number of species in Cordoba, with overlapping pollen seasons, and also to more favorable weather conditions. Trends in pollen season start dates were fairly stable over the study period, with a slight tendency to delayed onset in Cordoba and a modest advance in start date in Poznan. The pollen season end date also remained reasonably stable over the study, with only a slight tendency for the season to end earlier in Cordoba and later in Poznan. A clear trend towards declining annual pollen counts was recorded over the study period for all pollen types in both cities.

Peak Flow Meter Characteristics and Asthma.

Asthma is an episodic disease characterized by acute airway narrowing in at least two common scenarios. The first is when an irritant such as cigarette smoke, fumes from an industrial source, strong perfume, or even exercise cause an acute bronchospastic event. This type of asthma usually reverses with bronchodilator therapy in the first 2 hours with little subsequent airway inflammation and recovery of peak flows back to the normal range. The only other treatment may be avoidance of the irritant if possible. In a second type of clinical situation, an asthmatic develops ongoing airway inflammation due to daily pollen exposure, chronic cockroach exposure in the household, or other chronic condition causing airway irritation resulting in progressive inflammation and eventual bronchospasm poorly relieved by bronchodilators alone. These patients do not normalize peak flow immediately and require systemic steroids either as an inpatient or outpatient. Normalization of peak flow may occur in 3-4 days or may take up to several weeks of systemic steroids. In both cases, monitoring of airway caliber is done with a peak flow meter.

Numerical simulation of birch pollen dispersion with an operational weather forecast system

We included a parameterisation of the emissions of pollen grains into the comprehensive model system COSMO-ART. In addition, a detailed density distribution of birch trees within Switzerland was derived. Based on these new developments, we carried out numerical simulations of the dispersion of pollen grains for an episode that occurred in April 2006 over Switzerland and the adjacent regions. Since COSMO-ART is based on the operational forecast model of the German Weather Service, we are presenting a feasibility study of daily pollen forecast based on methods which have been developed during the last two decades for the treatment of anthropogenic aerosol. A comparison of the model results and very detailed pollen counts documents the current possibilities and the shortcomings of the method and gives hints for necessary improvements.

Aerobiological study of Fagaceae pollen in the middle-west of Spain

The concentration of airborne Fagaceae pollen in Salamanca and the correlations with some meteorological parameters have been examined. Castanea and Quercus pollen grains were collected from 1998 to 2004 using a Burkard spore trap. No pollen grains of Fagus were found. The main pollen season took place in April and May for Quercus and in June and July for Castanea. Yearly variations on these dates could be related to the influence of meteorological factors such as rainfall, temperature, or dominant winds. The highest values appeared in the year 2004 for both taxa. The Fagaceae airborne content was mainly due to Quercus pollen, Castanea having a scarce pollen content in the city of Salamanca. The highest counts of Fagaceae pollen grains were found from mid May to early June due to the pollen behavior of oaks. The cumulative counts varied over the years, with a mean value of 2,384 pollen grains, a highest total of 6,036 in 2004 and a lowest total of 954 in 2001. No cyclic variations were observed. Daily pollen concentrations presented positive correlation with temperature, negative with relative humidity and slightly negative with rainfall using Spearman's correlation coefficients, only in the case of Castanea, because the particular hourly distribution of rainfall during the spring might affect Quercus airborne pollen.

Airborne pollen calendar for Trieste (Italy), 1990–2004

Daily airborne pollen grains were collected in Trieste (1990–2004) using a Hirst‐type trap. A large quantity of pollen grains was found, the mean annual total being 48 082 grains. Daily counts were particularly high between March and June, the highest values being recorded between April and May. A total of 123 different pollen taxa from 80 families were identified. Almost half of the total pollen content came from introduced trees and shrubs, one fifth from natural woodlands, and one quarter from herbaceous taxa. This composition reflects the ornamental and ruderal flora of the town, as well as the natural vegetation surrounding the urban area. The pollen richness of both mesophilous and thermophilous taxa reflects the complexity of this zone, considered a “crossroad” of species of different chorological types. Total daily pollen concentrations were positively correlated with temperatures only in the pre‐peak period. The main taxa, except for Urticaceae, Pinus and Gramineae, displayed positive correlations with temperatures both in the main pollen season and in the pre‐peak period. The annual pollen sum of Ostrya was negatively correlated with total rainfall of the previous summer, and that of Pinus was negatively correlated with the winter severity.

Seasonal distribution of pollen in the atmosphere of Darwin, tropical Australia: Preliminary results

Pollen loads in the atmosphere of Darwin, a city located in the wet‐dry tropics of Australia, have been monitored for the period March 2004 to November 2005 as part of a large research program looking at atmospheric particles and human health. Seven pollen types dominate the pollen spectrum, the herbaceous families of Poaceae (grasses) and Cyperaceae (sedges), as well as several native tree and shrub taxa, Acacia, Callitris, Casuarina, Arecaceae and Myrtaceae. The pollen loads were found to have a strong seasonal component associated with the alternating wet (November to March) and dry (April to October) seasons of the region. Seventy percent of the yearly pollen load is captured during the dry season, with the peak pollen period occurring at the onset of the dry season (April–May) when most grasses are in flower. The daily pollen concentration decreases as the dry season progresses, accompanied by a change in composition; fewer herbaceous but increasing woody taxa. Preliminary health outcomes reveal a positive association between hay fever, Poaceae and Acacia pollen, as well as a significant association between total fungal spore concentrations and asthma. The Darwin record contrasts significantly with surveys conducted in the subtropical and temperate cities of Australia where temperature as opposed to rainfall and the prevalence of northern hemisphere exotic tree species have a greater influence over the seasonality and composition of the pollen loads.

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.

ASSESSING THE RELATIONSHIP BETWEEN SYMPTOMS OF ALLERGIC RHINOCONJUNCTIVITIS AND POLLEN COUNTS

The relationship between daily pollen counts during the peak pollen season and hay fever symptoms in known sufferers of pollen allergy was investigated in a Sydney hospital-based study. This paper develops statistical models for both the short term (day to day) associations and the longer term relationships between these time series. Possible effects of asthma status are investigated. The analyses illustrate how different relationships between time series may be explored in a simple way by working on different time scales with suitably transformed variables.

Temporal Distribution of Extreme Airborne Pollen Grain Concentrations in Szeged, Southern Hungary

P-127 Introduction: Pollen allergy has become a widespread disease by the end of the 20th century. The frequency of registered allergic illnesses has doubled and the number of cases of allergic asthma has become four times higher in Southern Hungary by the late 1990s over the last 40 years. The aim of the study is to detect sub-periods, i.e. “breaks”, in data sets of daily pollen concentration averages, which differ significantly from the means of the entire data sets. As a result of this, periods of highest pollen related health risk are indicated. Methods: The database consists of daily mean pollen counts of 24 species from the five-year period between 1997–2001 for the pollination term between 1 February–31 October. Calculations were performed only for the Main Pollination Periods. The applied statistical test is the Makra-test, which is considered as a new interpretation of the two-sample test. The basic question of this test is whether or not a significant difference can be found between the averages of an arbitrary sub-sample of a given data set, and the whole sample. Detection of the significant breaks was performed by the Monte Carlo method. Results: Sub-periods of the pollen count data sets for the 24 species, averages of which are significantly higher than the means of the whole data sets are distributed throughout the pollination term. Periods characterized by the highest pollen loads simultaneously at least by three species are the terms 25–26 March, 27–28 April, 6–8 June and 21–27 August, respectively. Poaceae, which have the longest pollination period, show both the longest sub-period of all species (41 days), average of which is significantly higher than that of their whole data set and, on the other hand, show the longest sub-period of all species (80 days), indicating significantly lower average than that of their whole data set. Considering all the 24 species, total average (20.2 days) of those sub-periods which show significantly lower averages than that of the whole data set is significantly longer than total average (14.7 days) of those sub-periods which indicate significantly higher averages than that of the whole data set. Discussion and Conclusions: Though the pollination period is considered to last from 1 February until 31 October, the significant positive breaks of the species are limited for the term of March–August. The most significant pollen loads that coincide at least for three species, are short. Among them 21–27 August is considered the period of most health risk in Szeged. The shorter average positive breaks are explained by their extremely high pollen release compared to that of the beginning and the end of the pollination term. Significant positive breaks are not the only parameter determining periods of highest health risk. Average pollen grain concentrations and pollen aggressivity are also important factors that need to be taken into account.

Extremereignisse beim Pollenflug

Extreme events like storms, floods of rare magnitude or drought periods can be statistically analyzed by the parametric model of the Gumbel distribution (for the maximum). Based on long-term observations, the frequency of such extreme events can be calculated. This approach was, therefore, chosen to investigate the extreme events occurring in the case of airborne pollen. Extreme events in this case means the largest daily pollen count in each of the years of the periods studied. The study, based on the Basel pollen observation, indicates how often extreme events have to be expected and how often a certain amount of either birch pollen or grass pollen might occur. A general trend in more extreme events concerning airborne pollen cannot be observed by using the Loess smoothing approach.

Aeroallergen prevalence in the northern New Jersey-New York City metropolitan area: a 15-year summary

Elevated environmental pollen levels result in allergic and asthmatic symptoms in sensitive individuals. To present data collected during a 15-year period demonstrating the seasonal pollen variation in a metropolitan area. Pollen was collected daily except for weekends. Pollen counts were counted using light microscopy and were used to calculate the average daily pollen count per month between March 1 and October 31 of each calendar year. The month in which each class of pollen reached the highest level (peak) was analyzed across the sampling period. Spearman p correlation coefficients were calculated to show changes in peak pollen levels across time. The average daily pollen level (tree, grasses, and weeds) for each month was analyzed (1987-2002). Tree pollen peaked in May and composed 98.7% of the measurable pollen between March and May. Grass pollen had a biphasic peak (June and September), representing 42.9% of measurable pollen in July and 6.4% in September. Weed and ragweed levels peaked in September. Total weed pollen constituted 93.5% of the measurable pollen between August and October. The combined total pollen levels peaked in May. The highest annual peak tree pollen count was observed between 1992 and 1997, with a linear relationship between tree and total pollen (R2 = 0.97); highest levels of grass pollen were observed between 1993 and 1997; and highest levels of weed pollen were observed between 1993 and 1995. A trend toward declining levels of total pollen was observed between 1993 and 2002. This declining trend was most pronounced for weed pollen. Aeroallergens pollinate sequentially, starting with trees in the spring, grass throughout the summer, and weeds in late summer to early fall. Pollen levels have declined from 1993 to the present. The most pronounced drop has been in weed pollen levels. Grass pollen demonstrates a biphasic pattern. Tree pollen composes most annual pollen measured in the northern New Jersey-New York City area.

Aerobiology of Fagaceae pollen in Trieste (NE Italy)

The aerobiological behaviour of Fagaceae in Trieste and the correlations with the meteorological parameters were examined. Airborne pollen grains of Castanea, Fagus and Quercus were collected from 1990 to 2003 using a Hirst type spore trap. The main pollen season (MPS) takes place in April and May for Quercus and Fagus, in June and July for Castanea. The highest values occur in year 1993 for Quercus, in 1998 for Castanea and in 1992 for Fagus. The Fagaceae content of the air is mainly due to Quercus and Castanea pollen, Fagus usually having a scarce pollen shedding in Trieste. The highest counts of Fagaceae pollen grains are found from late April to mid May and are mainly due to the pollen shedding of oaks. The cumulative counts vary over the years, with a mean value of 2.719 pollen grains, a lowest total of 1.341 in 2002 and a highest total of 4.704 in 1993. No positive nor negative long-term trends in pollen shedding are found. No cyclic variations were observed. Spearman’s correlation was used to establish the relationship between the daily pollen counts and the daily meteorological data. Daily pollen concentrations present sometimes positive correlation with temperature, negative with rainfall and wind speed, and no correlation with humidity. Fagus and Quercus start dates result positively correlated between themselves. Significant correlations are found between the start of MPS and the mean and maximum temperature in March for Fagus and Quercus, and May for Castanea.