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.     

Airborne ascospores in Tetouan (NW Morocco) and meteorological parameters

Ascospores are frequently found as airborne fungal spores and recognized in various areas as an important cause of respiratory allergies. The main objective of the study was to determine the relationship between airborne ascospores and meteorological parameters using multivariate canonical correspondence analysis (CCA) and Spearman correlation. The aerobiological monitoring of fungal spores was performed over 5 years (2009–2013) using a Burkard volumetric spore traps. Seven main types of ascospores were identified: Leptosphaeria, Pleospora, Venturia, Diatrype, Chaetomium, Sporormiella and Ascobolus. The CCA results showed that all applied variables accounted for 27.4 % of the total variance in the spore data in the 5 years. The largest contribution to the total variance was explained in this period by the maximum air temperature (10.3 %). The effect of meteorological factors varied among years. The highest values of the total variance in the spore data, explained by the statistically significant variables, were observed in 2012 (28.6 %), with the highest contribution to minimum relative humidity (8.0 %). Most ascospores showed positive and statistically significant correlation with relative humidity and rainfall. In contrast, ascospores of Chaetomium were negatively correlated with precipitation and the relative humidity and positively with temperature. Based on these results, epidemiological and allergological studies must deserve more attention to estimate the allergenic potential of the ascospores.     

Pollen production in anemophilous species of the Poaceae family in Tetouan (NW Morocco)

Total pollen production per inflorescence and per square meter were studied in anemophilous species of the Poaceae family, to determine the relative contribution of each species to the total load of pollen released and to identify the species with the highest potential pollen emission. This was done by calculating the number of pollen grains per flower and per inflorescence and by estimating the density of inflorescences in an area of one square meter. Pollen production per inflorescence varied between 12,000 and 15 million grains, often being higher in the perennial species. Mountainous, grassland, riverside, and littoral areas contributed similarly to the amount of pollen grain production per square meter. Species such as Gaudinia fragilis, Hordeum murinum, Lolium rigidum, and Trisetaria panicea, with high pollen records, were found in all the studied areas. Aerobiological analysis will be undertaken to determine the main pollen season of Poaceae species. The results obtained are of great importance for respiratory health management in this region.     

The effect of meteorological parameters on diurnal patterns of airborne olive pollen concentration

Aerobiological studies carried out in the atmosphere of Granada using a Hirst-type volumetric spore trap during the period 1993-1996 show that there is not a single diurnal pattern for olive pollen (Olea europaea L.) over the course of the main pollen season. Examination of the behaviour of airborne olive pollen concentration allows the establishment of either regular (54.4% of the studied days) or irregular (45.6% of the time) patterns of diurnal variation. On a given day, the pattern found will depend on a combination of different factors: the origin of the captured pollen (either local or regional), source distribution in relation to the pollen sampler, topography, and different meteorological variables (mean air temperature, sunshine hours, total rainfall, relative humidity, wind speed and direction, and periods of calm). Regional sources were significant contributors to city centre pollen concentrations when moderate (< 10 km/h) winds from the 4th quadrant and warm temperatures (19-26 C) allow swift transport from the W-NW of the province.     

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

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

Estimating the daily Poaceae pollen concentration in Hungary by linear regression conditioning on weather types

Many people suffer from allergic diseases and much research has illustrated that pollen can play an important role in inducing such diseases. The fact that allergic symptoms are more prevalent in larger cities may be related to the increase in air pollution resulting from the mineral or synthetic materials released into the atmosphere by cars and factories. On the other hand, recent investigations have considered that it is the exinic mineral elements which induce or control pollen allergenicity. Different degrees of Pinus elderica allergenicity in guinea pigs were studied along with the ultrastructural changes and variation in the mineral element concentration of the pollen exine after exposure of the pollen to the atmosphere of Tehran for certain periods. The results were analyzed qualitively and also statistically by the unpaired T test, whenever necessary. P values of < 0.005 were considered significant.     

Airborne Pinus pollen in the atmosphere of Brisbane, Australia and relationships with meteorological parameters

Relationships between weather parameters andairborne pollen loads of Pinus inBrisbane, Australia have been investigated overthe five-year period, June 1994–May 1999.Pinus pollen accounts for 4.5% of the annualairborne pollen load in Brisbane where thePinus season is confined to the winter months,July–early September. During the samplingperiod loads of 11–>100 grains m³ wererecorded on 24 days and 1–10 grains m³ on204 days. The onset and peak dates wereconsistent across each season, whereas the enddates varied. The onset of the Pinuspollen season coincided with the coolestaverage monthly temperatures (< 22°C),lowest rainfall (< 7mm), and four weeks afterdaily minimum temperatures fell to 5–9°Cin late autumn. Correlations obtained betweendaily airborne Pinus pollen counts andtemperature/rainfall parameters show thatdensities of airborne Pinus pollen arenegatively correlated with maximum temperature(p < 0.0001), minimum temperature (p < 0.0001)and rainfall (p < 0.05) during the mainpollination period. The mean duration of eachpollen season was 52 days; longer seasons wereshown to be directly related to lower averageseasonal maximum temperatures (r² = 0.85,p = 0.025). These results signify that maximumand minimum temperatures are the majorparameters that influence the onset andduration of the Pinus pollen season inthe environs of Brisbane. Respiratory allergyis an important health issue in Brisbane,Australia, but it remains unknown whether ornot airborne Pinus pollen is acontributing factor.     

Poaceae pollen concentrations in the atmosphere of three inland Croatian sites (2003-2004)

The aim of the study was to determine the length of Poaceae pollen season, intradiurnal, daily and monthly pollen variation, and the effect of some meteorological parameters on atmospheric pollen concentration, at three monitoring sites in inland Croatia during the 2003-2004 period. Seven-day Hirst volumetric pollen and spore traps were used for pollen sampling. At all three monitoring sites considerably higher precipitation and lower average temperature in 2004 led to a marked decrease in the grass pollen concentration in the air at all three monitoring sites. The highest grass pollen concentrations were recorded in Ivani? Grad (typical rural area), considerably lower in Samobor (effect of forest vegetation), and lowest in Zagreb (urban area). The highest atmospheric Poaceae pollen concentrations in inland Croatia were generally recorded in May and June. The highest intradiurnal concentrations were recorded between 8.00 and 12.00 a.m. Results of this aeropalynologic study are expected to help in preventing the symptoms of allergic reaction in individuals with Poaceae pollen hypersensitivity.     

Effects of meteorological parameters and plantdistribution on Chenopodiaceae-Amaranthaceae, Quercus and Olea airborne pollen concentrationsin the atmosphere of Cartagena (Spain)

We have studied the effects of various meteorologicalparameters and plant distribution on the airborneconcentrations of three different pollen types:Chenopodiaceae-Amaranthaceae, Quercus and Olea, in the city of Cartagena, situated in SouthwestEurope. The aerobiological study has been carried outfrom March 1993 to March 1997, using a Hirst-typeLanzoni 2000 trap, situated on the roof of the citytrain station. Meteorological data were supplied bythe Environmental Service of Cartagena's Town Hall.Daily pollen concentrations were standardised.Correlation analysis showed the importance ofmeteorological data on airborne pollen concentrations.On the other hand, ANOVA analyses depicted theinfluence of vegetation distribution in relation tosampler location and wind directions. Finally,multiple regression analyses allowed us to developcorrelation models for the three different pollentypes considered, accounting for 32%(Chenopodiaceae-Amaranthaceae), 19% (Quercus),and 26% (Olea) of the variation in the airbornepollen concentration.     

Airborne olive pollen in Vigo (Northwest Spain): a survey to forecast the onset and daily concentrations of the pollen season

Temperature is one of the main factors affecting the start of flowering in tree species that flower at the beginning of spring. Knowledge of the chilling and heat needs required by plants to overcome the period of dormancy enables us to determine the onset of pollination, which is of great importance to allergy sufferers. This study attempted to obtain behaviour models with a view to determining both the onset of the olive pollen season and daily pollen concentrations during the pollination period in Vigo. Monitoring was carried out using a Lanzoni VPPS 2000 pollen trap, from 1995 to 2002 inclusive.

Olea pollen is mainly detected during the spring, principally in May. Given the geographical location, the very limited presence of this tree in the study area and the low Olea pollen concentrations detected in northern Spain as a whole, the values recorded here in the atmosphere of Vigo are particularly striking. A strong correlation was observed between total quantity olive pollen collected over the season and rainfall recorded during the second fortnight in February. According to the proposed model, an average of 680 Chilling Hours (CH) are necessary to overcome the chill period and break the state of bud dormancy, and 481 Growth Degree Days (GDD) °C are needed to induce flowering. Models for predicting daily mean pollen concentrations combine temperature and the previous days' pollen concentrations as predictor variables to provide a high level of prediction.     

Poaceae pollen in the atmosphere of Santiago de Compostela: its relationship with meteorology

This work analyses the behaviour of Poaceae pollen during a 3-year sampling period (1993–1995) in the city of Santiago de Compostela (Spain). This taxon is shown to be one of the most abundant in the atmosphere, with representation percentages greater than or equal to 20% of total pollen registered during the said period. Its main pollination period is centred on the months of June and July, with slight modifications in the beginning and finalization dates of the years 1993 and 1994 and a significantly earlier beginning in the year 1995. Overall results show that its presence may be considered significant from the end of May to the first days of August. The differences in Poaceae pollen representation are related to variations in temperature, precipitation and hours of sunshine.     

Fluctuations of grass pollen content in the atmosphere of East Perugia and meteorological correlations (year 1989)

Summary Gramineae pollination from a pollen monitoring station located in the eastern suburb of Perugia and meteorological correlations are reported. The data refers to the year 1989. Grass pollen peak pollination was from May to July; in this period the influence of relative humidity and of temperature on pollen concentration was very high. Phenological observations, to identify the time of maximum stamen extension in the most common genera in the area, are also reported. During the period of investigation the counts of pollen grains over four-hour periods showed a regular diurnal rhythm with peaks of concentration in the four-hour period 16.00–20.00. Aerosporological data and meteorological data related to four-hour periods were correlated following different criteria.     

Spatial and temporal variations of pollen concentrations in Islamabad (Pakistan): effect of meteorological parameters and impact on human health

This study focuses on the identification and quantification of airborne pollen grains from allergenic plant species and their relationship with meteorological factors, i.e. maximum and minimum daily temperature, relative humidity, rainfall and wind speed in the city of Islamabad, Pakistan. An aerobiological data set (2010–2012), collected using rotorod samplers in five different sectors of the city, was supplied by the Pakistan Meteorological Department. Pollen of eight allergenic species was identified amongst which Broussonetia papyrifera exceeded the highest pollen level and, therefore, likely played a key role in aggravating the symptoms of pollen allergy in the city. The mean weekly pollen counts were next correlated with the weekly number of allergic patients visiting hospitals during 2010–2011. Clinical data were acquired from the Pakistan Institute of Medical Sciences. The highest number of allergic patients visiting hospital was usually observed during weeks with high pollen level. These results suggest a close relationship between the pollen concentration in the air and the allergy symptoms. Spearman’s rank correlation analysis was performed to establish the relationships between meteorological parameters and daily average pollen counts. A pollen calendar for the Islamabad city was also prepared to provide a guide for the timing and duration of season for all encountered pollen types.     

Airborne pollen concentration in the region of Braga, Portugal, and its relationship with meteorological parameters

The variation in airborne pollen concentrationof the Braga region (Portugal) was studied inspringtime, during the flowering of Vitisvinifera. The data set was obtained for twoconsecutive years (1999 and 2000), using aCour-type sampler.During this period, thirty-six taxa wereobserved in a total of 3,200 pollengrains m^-3 of air (CPA). The main pollentypes observed were Olea, Poaceaea,nd Castanea, representing 74% of thepollen spectrum.The airborne pollen concentration (CPA) wassignificantly correlated with certainmeteorological parameters. Pollen concentrationwas positively correlated with temperature andwind direction (East and Northeast) andnegatively correlated with rainfall and numberof rainy days.     

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.     

Airborne pollen patterns in Mar del Plata atmosphere (Argentina) and its relationship with meteorological conditions

This work is part of a series of aerobiological researches conducted in the city of Mar del Plata, Argentina. The annual, seasonal and daily features of the pollen cloud were analyzed over 2 years, together with the effects of the meteorological variables. Cupressaceae amounted to 75 and 54% of the annual total in each year, and it was analyzed separately due to its proven overrepresentation. Eighty-five pollen types were registered during the 2 years, bearing a similar annual pattern (more than 50% from August to November, December also being an important month). Arboreal pollen predominated between late winter and spring (61 and 49% of the annual total), while non-arboreal pollen did so from late spring to summer. The observed seasonality was significantly correlated with the monthly mean temperatures and associated with its effect on phenology. No significant differences along the day were detected between years and 50% of the daily total was recorded between 1000 and 1600 hours. The maximum concentration was registered at 1000 hours in spring and summer, but later in autumn and winter. Regarding the hourly scale, the significant correlation of total pollen with temperature and wind speed was positive, albeit negative with relative humidity. These effects are linked to airborne pollen release and transport. The role rainfall plays on airborne pollen is discussed. To interpret the results, it is important to consider the time scale at which the aerobiological phenomenon is analyzed.     

Pinus pollen in the atmosphere of Vigo and its relationship to meteorological factors

The Pinus genus has an elevated pollen production and an anemophilous nature. Although considered to be hypoallergenic, numerous cases of allergies caused by Pinus pollen have been cited and different authors believe that its allergenicity should be studied in more depth. In the city of Vigo several patients have tested positive for Pinus pollen extracts in skin tests, some of them being mono-sensitive to such pollens. In order to ascertain the behaviour of Pinus pollen and its correlation to the main meteorological factors, we carried out an aerobiological study in the city of Vigo from 1995 to 1998 by using a Hirst active-impact volumetric sporetrap, model Lanzoni VPPS 2000, placed on the left bank of the Vigo estuary (42°14’15’’N, 8°43’30’’W). Pinus has high quantitative importance in the airborne pollen spectrum of the city. It is one of the best represented taxa constituting 13%–20% of the total annual pollen levels. The quantity of Pinus pollen present in the atmosphere of the city of Vigo throughout a year is 5751 grains (as the average for the sampled years), with a very long pollination period, from the middle of January until May. The maximum concentration was recorded in 1998 with 1105 grains/m³ on 3 March, a much greater value than those for the previous years. At the end of its pollination period there is usually a final increase in Pinus pollen concentrations coinciding with the pollination of Pinus silvestris, which are more abundant in mountainous areas far from the city. Received: 17 March 1999 / Revised: 20 December 1999 / Accepted: 20 December 1999     

Influence of meteorological parameters on Olea flowering date and airborne pollen concentration in four regions of Portugal

For calculating the total annual Olea pollen concentration, the onset of the main pollen season and the peak pollen concentration dates, using data from 1998 to 2004, predictive models were developed using multiple regression analysis. Four Portuguese regions were studied: Reguengos de Monsaraz, Valença do Douro, Braga and Elvas. The effect of some meteorological parameters such as temperature and precipitation on Olea spatial and temporal airborne pollen distribution was studied. The best correlations were found when only the pre‐peak period was used, with thermal parameters (maximum temperature) showing the highest correlation with airborne pollen distribution. Independent variables, selected by regression analysis for the predictive models, with the greatest influence on the Olea main pollen season features were accumulated number of days with rain and rainfall in the previous autumn, and temperatures (average and minimum) from January through March. The models predict 59 to 99% of the total airborne pollen concentration recorded and the initial and peak concentration dates of the main Olea pollen season.