scholarly journals An exploratory analysis of seasonal and intraseasonal variations of the main airborne pollen types in Sunchales city, Argentina

2021 ◽  
Vol 56 (3) ◽  
Author(s):  
Claudio Pérez ◽  
Mauro Covi ◽  
María Gassmann ◽  
Ana Ulke
Keyword(s):  
Seasonal Variability ◽  
Airborne Pollen ◽  
Time Of Day ◽  
Intraseasonal Variations ◽  
Pollen Transport ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Burkard Trap ◽  
The City ◽  
Airborne Pollen Concentration

Background and aims: The study of the seasonal and intra-seasonal variability of the airborne pollen concentration is of paramount importance to understand the relationships with the emitting vegetation and the atmospheric parameters that modulate pollen transport. This research aims to study these variabilities in Sunchales, a city located in the center-east of Argentina. M&M: Atmospheric monitoring was carried out with a Burkard trap during two seasons in 2012 and 2013 on the outskirts of the city. Results & Conclusions: The pollination periods of the studied pollen types show a delay in 2013 compared to the previous year, presumably related to a greater amount of cumulative heat units in 2012. However, the integral pollen for the period 2013 was 1.4 times higher than 2012, a fact that is not explained by accumulated precipitation but by the time of day when the hydrometeors occur. Binned pollen concentrations show that the highest concentrations coincide with the urban location of the tree sources while the herbaceous ones show an association with a rural origin. Regarding the intra-seasonal variability, the highest proportion of the airborne pollen variance accumulates on the synoptic-scale (80 - 60%) with periods between 3 and 10 days. During 2012 long waves predominated (> 5.5 days) while in 2013 medium waves prevailed (3.9 - 5.5 days).

scholarly journals Land-Use and Height of Pollen Sampling Affect Pollen Exposure in Munich, Germany

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 145 ◽  
Author(s):  
Jesús Rojo ◽  
Jose Oteros ◽  
Antonio Picornell ◽  
Franziska Ruëff ◽  
Barbora Werchan ◽  
...  
Keyword(s):  
Airborne Pollen ◽  
Pollen Grains ◽  
Ground Level ◽  
Large Area ◽  
Dispersal Capacity ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Pollen Sources ◽  
Poaceae Pollen ◽  
The City

Airborne pollen concentrations vary depending on the location of the pollen trap with respect to the pollen sources. Two Hirst-type pollen traps were analyzed within the city of Munich (Germany): one trap was located 2 m above ground level (AGL) and the other one at rooftop (35 m AGL), 4.2 km apart. In general, 1.4 ± 0.5 times higher pollen amounts were measured by the trap located at ground level, but this effect was less than expected considering the height difference between the traps. Pollen from woody trees such as Alnus, Betula, Corylus, Fraxinus, Picea, Pinus and Quercus showed a good agreement between the traps in terms of timing and intensity. Similar amounts of pollen were recorded in the two traps when pollen sources were more abundant outside of the city. In contrast, pollen concentrations from Cupressaceae/Taxaceae, Carpinus and Tilia were influenced by nearby pollen sources. The representativeness of both traps for herbaceous pollen depended on the dispersal capacity of the pollen grains, and in the case of Poaceae pollen, nearby pollen sources may influence the pollen content in the air. The timing of the pollen season was similar for both sites; however, the season for some pollen types ended later at ground level probably due to resuspension processes that would favor recirculation of pollen closer to ground level. We believe measurements from the higher station provides a picture of background pollen levels representative of a large area, to which local sources add additional and more variable pollen amounts.

scholarly journals Near-surface and columnar measurements with a micro pulse lidar of atmospheric pollen in Barcelona, Spain

2016 ◽  
Vol 16 (11) ◽  
pp. 6805-6821 ◽  
Author(s):  
Michaël Sicard ◽  
Rebeca Izquierdo ◽  
Marta Alarcón ◽  
Jordina Belmonte ◽  
Adolfo Comerón ◽  
...  
Keyword(s):  
Airborne Pollen ◽  
Correlation Coefficients ◽  
Vertical Motion ◽  
Surface Concentration ◽  
Correlation Study ◽  
Near Surface ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Micro Pulse Lidar ◽  
Depolarization Ratios

Abstract. We present for the first time continuous hourly measurements of pollen near-surface concentration and lidar-derived profiles of particle backscatter coefficients and of volume and particle depolarization ratios during a 5-day pollination event observed in Barcelona, Spain, between 27 and 31 March 2015. Daily average concentrations ranged from 1082 to 2830 pollen m−3. Platanus and Pinus pollen types represented together more than 80 % of the total pollen. Maximum hourly pollen concentrations of 4700 and 1200 m−3 were found for Platanus and Pinus, respectively. Every day a clear diurnal cycle caused by the vertical transport of the airborne pollen was visible on the lidar-derived profiles with maxima usually reached between 12:00 and 15:00 UT. A method based on the lidar polarization capabilities was used to retrieve the contribution of the pollen to the total aerosol optical depth (AOD). On average the diurnal (09:00–17:00 UT) pollen AOD was 0.05, which represented 29 % of the total AOD. Maximum values of the pollen AOD and its contribution to the total AOD reached 0.12 and 78 %, respectively. The diurnal means of the volume and particle depolarization ratios in the pollen plume were 0.08 and 0.14, with hourly maxima of 0.18 and 0.33, respectively. The diurnal mean of the height of the pollen plume was found at 1.24 km with maxima varying in the range of 1.47–1.78 km. A correlation study is performed (1) between the depolarization ratios and the pollen near-surface concentration to evaluate the ability of the former parameter to monitor pollen release and (2) between the depolarization ratios as well as pollen AOD and surface downward solar fluxes, which cause the atmospheric turbulences responsible for the particle vertical motion, to examine the dependency of the depolarization ratios and the pollen AOD upon solar fluxes. For the volume depolarization ratio the first correlation study yields to correlation coefficients ranging 0.00–0.81 and the second to correlation coefficients ranging 0.49–0.86.

scholarly journals The Relationship between Metrological Parameters and Total Airborne Pollen Concentration in Atmosphere of Khartoum City During 2018

2021 ◽  
pp. 93-109
Author(s):  
Ejlal Sanad Mohammed Motwaly ◽  
A.G. Elfadil ◽  
Ahmed Mudawi Musa
Keyword(s):  
Relative Humidity ◽  
Meteorological Parameters ◽  
Airborne Pollen ◽  
Maximum Temperature ◽  
Pollen Concentration ◽  
Spore Trap ◽  
Pollen Concentrations ◽  
The Relationship ◽  
Metrological Parameters ◽  
Airborne Pollen Concentration

This study is aimed to find out the effect and relationship between metrological parameters and total airborne pollen concentration in atmosphere in Khartoum city (Sudan). For that purpose, one-year data during 2018 of Total Airborne Pollen Concentration (TAPC) and meteorological parameters is utilized. Pollen concentration in the atmosphere was measured using Non-volumetric air sampler (Vertical cylinder spore trap). The descriptive statistic of TAPC and metrological parameters were presented. The result showed TAPC in 2018 reached to their maximum in August (37.5/m³), and the minimum in June (14/ m³). Analysis of the relationship between TAPC and meteorological parameters showed that variations in the pollen concentrations were mainly affected by maximum temperature. In addition, there were substantial differences in these relationships in different seasons. In Autumn, they were affected by the rain falls, maximum temperature and relative humidity; in summer, they were affected by maximum temperature; and in winter, they were affected by maximum temperature and relative humidity. Temperature, rain falls and relative humidity promote plant growth and blooming. As well as the results show wind direction was significant on seasonally TAPC especially in Autumn. The results found significant effects between the meteorological on TAPC, were it is showed 72 % are affecting on TAPC refer to meteorological parameters and 28 % refer to another factors.

Influence of Saharan-Sahel dust outbreaks on pollen exposure in the Iberian Mediterranean areas

2021 ◽  
Author(s):  
Jesús Rojo ◽  
José María Moreno ◽  
Jorge Romero-Morte ◽  
Beatriz Lara ◽  
Belén Elvira-Rendueles ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Mineral Dust ◽  
Airborne Pollen ◽  
Potential Effect ◽  
Dust Particles ◽  
Simultaneous Occurrence ◽  
Air Mass ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Pollen Exposure

<p>Airborne particulate matter such as mineral dust comes mainly from natural sources, and the arid regions of Sahara and Sahel in Africa release large amounts of the aerosols dispersed worldwide. There is evidence of concomitant presence of desert dust particles and bioaerosols such as pollen grains in the atmosphere, which produce a significant decline in air quality during the dust intrusions events. However, there is little knowledge about the influence of dust episodes on pollen exposure in allergy sufferers as well as the causes that may produce a potential effect of the intrusions on airborne pollen levels. This potential effect on the airborne pollen concentrations is analysed in the Iberian Mediterranean region in this study. Mediterranean countries are strongly affected by Saharan-Sahel dust intrusions, and the Iberian territory, specially the central and southern areas, suffer frequently great incidence of dust episodes due to its geographic location. In this study firstly, the simultaneous occurrence between airborne pollen peaks and Saharan-Sahel dust intrusions were analysed and compared with the behaviour in the days before and after the dust intrusions in the central and south-eastern Iberian Peninsula. Secondly, the weather conditions favouring high pollen concentrations during dust episodes namely prevalent winds, air mass pathways and variations in other meteorological variables like air temperature, relative humidity or atmospheric pressure were studied.</p><p>Pollen peaks often coincided with dust episodes during the pollen season in the central Iberian Peninsula. The increase of the airborne pollen concentrations during the dust episodes is clear in inland Iberian areas, although this was not the case in coastal areas of the southeast where pollen concentrations could even be seen to decrease when easterly winds from the sea prevailed during dust intrusions. Total pollen concentrations and also pollen types such as Olea, Poaceae and Quercus showed an increase in the central Iberian Peninsula during the dust episodes when two meteorological phenomena occurred simultaneously: 1) prevailing winds came from large areas of the main wind-pollinated pollen sources at medium or short scale (mainly from western and southwestern areas); and 2) optimal meteorological conditions that favoured pollen release and dispersal into the atmosphere (mainly high temperatures and low humidity). Both these conditions often occur during Saharan-Sahel dust intrusions in the centre. The findings suggest that the proportion of long-range transport is lower than those produced in medium and short distance by dust intrusions of air masses. Therefore, maximum pollen peaks are most likely to occur during dust episodes in the central Iberian Peninsula dramatically increasing the risk of outbreaks of pollinosis and other respiratory diseases in the population. The negative effects of the mineral dust on public health are well known, even more so when allergenic biological agents are co-transported together by the air mass movements coming from desert areas. The findings of this study have very relevant implications for defining health-emergency alerts for severe Saharan-Sahel dust outbreaks.</p>

scholarly journals Near-surface and columnar measurements with a Micro Pulse Lidar of atmospheric pollen in Barcelona, Spain

2016 ◽  
Author(s):  
Michaël Sicard ◽  
Rebeca Izquierdo ◽  
Marta Alarcón ◽  
Jordina Belmonte ◽  
Adolfo Comerón ◽  
...  
Keyword(s):  
Airborne Pollen ◽  
Correlation Coefficients ◽  
Vertical Motion ◽  
Surface Concentration ◽  
Correlation Study ◽  
Near Surface ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Micro Pulse Lidar ◽  
Depolarization Ratios

Abstract. We present for the first time continuous hourly measurements of pollen near-surface concentration and lidar-derived profiles of particle backscatter coefficients and of volume and particle depolarization ratios during a 5-day pollination event observed in Barcelona, Spain, between 27–31 March, 2015. Daily average concentrations ranged 1082–2830 pollen m−3 day−1. Platanus and Pinus pollen types represented together more than 80 % of the total pollen. Maximum hourly pollen concentrations of 4700 and 1200 m−3 h−1 were found for Platanus and Pinus, respectively. Everyday a clear diurnal cycle caused by the vertical transport of the airborne pollen was visible on the lidar-derived profiles with maxima usually reached between 12 and 15 UT. A method based on the lidar polarization capabilities was used to retrieve the contribution of the pollen to the total aerosol optical depth (AOD). On average the diurnal (9–17 UT) pollen AOD was 0.05 which represented 29 % of the total AOD. Maximum values of the pollen AOD and its contribution to the total AOD reached 0.12 and 78 %, respectively. The diurnal means of the volume and particle depolarization ratios in the pollen plume were 0.08 and 0.14, with hourly maxima of 0.18 and 0.33, respectively. The diurnal mean of the height of the pollen plume was found at 1.24 km with maxima varying in the range 1.47–1.78 km. A correlation study is performed (1) between the depolarization ratios and the pollen near-surface concentration to evaluate the ability of the former parameter to monitor pollen release, and (2) between the depolarization ratios and surface downward solar fluxes, which cause the atmospheric turbulences responsible for the particle vertical motion, to examine the dependency of the depolarization ratios upon solar fluxes. For the volume depolarization ratio the first correlation study yields to correlation coefficients ranging 0.00–0.81 and the second to correlation coefficients ranging 0.70–0.86.

scholarly journals A Survey of Atmospheric Pollen and Spores in North-Western Nigeria

2018 ◽  
Vol 10 (2) ◽  
pp. 182-192
Author(s):  
Olugbenga Shadrak ALEBIOSU ◽  
Olusola H. ADEKANMBI
Keyword(s):  
Meteorological Parameters ◽  
Airborne Pollen ◽  
Health Concern ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Atmospheric Pollen ◽  
Local Plants ◽  
Study Sites ◽  
The Impact ◽  
North Western

The incidence of airborne pollen occurring as aeroallergens of varied levels at different periods of the year has generated some public health concern globally. The present study was conducted in order to examine the monthly depositional rate of airborne pollen and fern spores, as well as the impact of meteorological parameters and local plants on pollen distribution at two study sites in Kaduna and Sokoto States of North Western Nigeria. The study spanned a period of one year, during which a modified Tauber pollen sampler was employed in the collection of atmospheric pollen and fern spores; local plants were also enumerated. Residual solution was collected monthly, subjected to acetolysis and the treated residues were viewed for microscopic studies. The results reveal monthly distribution of airborne pollen and fern spore types at the study sites during the sampling period. Dominant pollen types in Kaduna State were those of Alchornea laxiflora, Pinus caribaea, Terminalia sp., Sapotaceae and Poaceae family. Pollen of Syzygium guineense, Alchornea sp., Sapotaceae and Poaceae dominated in Sokoto State. Spores of Pteris sp., Nephrolepis sp. and a trilete fern were also recovered at both locations. Some local plants in the immediate vegetation contributed to the aeroflora of these locations. No significant correlation was recorded between monthly total pollen concentrations and mean monthly meteorological parameters of the locations. It is imperative to investigate the allergenicity of these dominant pollen types, so as to aid pollen hypersensitive individuals in adopting appropriate prophylactic measures.

scholarly journals 2350 Creating a comprehensive municipal inventory of common ragweed (Ambrosia artemisiifolia) to predict allergenic pollen exposures

2018 ◽  
Vol 2 (S1) ◽  
pp. 7-7
Author(s):  
Daniel S. W. Katz ◽  
Stuart Batterman
Keyword(s):  
Remote Sensing ◽  
Management Practices ◽  
Airborne Pollen ◽  
Ambrosia Artemisiifolia ◽  
Allergenic Pollen ◽  
Pollen Production ◽  
Common Ragweed ◽  
Lack Of Information ◽  
Pollen Concentrations ◽  
The City

OBJECTIVES/SPECIFIC AIMS: One of the key difficulties in predicting allergenic pollen exposures has been a lack of information on source plant location and abundance. However, the increasing availability of spatially explicit data from remote sensing offers new opportunities to create comprehensive inventories of allergenic pollen producing plants. METHODS/STUDY POPULATION: In this study, we use a spatially oriented field survey to map common ragweed (Ambrosia artemisiifolia) in Detroit, MI, USA. We then combine this with remote sensing imagery and LiDAR to predict ragweed presence and potential pollen production across 344 km2 of Detroit. Finally, we compare this with measurements of airborne pollen concentrations collected throughout the city. RESULTS/ANTICIPATED RESULTS: Our initial results show that ragweed is present in ~2% of the city, and its presence and abundance are strongly associated with demolished building (p<0.001). The uneven distribution of ragweed plants across the city leads to substantially higher pollen concentrations in neighborhoods where more buildings have been recently demolished. DISCUSSION/SIGNIFICANCE OF IMPACT: Our approach offers an effective way to quantify allergenic pollen production, airborne concentrations, and exposures across a large metropolitan area. This in turn provides insight on how to best reduce airborne pollen concentrations: in this case, by changing post-demolition land management practices.

scholarly journals Análisis del contenido aeropolínico estival en la provincia de Málaga

2001 ◽  
Vol 26 ◽  
pp. 89-98
Author(s):  
Marta Recio ◽  
M. Mar Trigo ◽  
Silvia Docampo ◽  
Baltasar Cabezudo
Keyword(s):  
Airborne Pollen ◽  
Summer Season ◽  
Palabras Clave ◽  
Low Concentrations ◽  
Pollen Content ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Atmospheric Pollen ◽  
Annual Total ◽  
Total Pollen

RESUMEN. Análisis del contenido aeropolínico estival en la provincia de Málaga. En el presente trabajo se realiza un estudio del contenido polínico de la atmósfera de la provincia de Málaga durante cl periodo estival (Julio-Septiembre) tomando los registros obtenidos durante los últimos años en varias localidades de la provincia: Málaga (1992-1999), Estepona (1995-1997), Antequera (1998-1999) y Nerja (2000). En general, durante estos tres meses se recoge sólo entre el 3 y el 6% del polen anual, estando el espectro aeropolínico estival de Málaga representado básicamente por 14 tipos polínicos: Eucalyptus, Castanea, Parkinsotzia, Cannabis, Apiaceae, Ligustrum, Chenopodiaceae-Amaranthaceae, Palmae, Compositae, Artemisia, Typha, Cyperaceae, Poaceae y U rticaceae. Los tipos que alcanzan mayores concentraciones son Eucalyptus, Chenopodiaceae-Amaranthaceae y Poaceae. El resto de los taxa citados aparecen en concentraciones muy bajas. Determinados taxa presentan concentraciones más elevadas en determinadas estaciones de muestreo: Castanea y Compositae en Antequera, Palmae y Parkinsonia en Málaga, y Artemisia en Nerja. La evolución a lo largo de los tres meses muestra, en general, dos tipos de tendencia: una descendente de Julio a Agosto (presente en todos los tipos polínicos estudiados, excepto en Artemisia y Palinae, y en todas las zonas estudiadas) y otra ascendente, de Agosto a Septiembre, de pequeña intensidad, aunque muy acusada para los dos tipos anteriores y para Chenopodiaceae-Amaranthaceae y Cotnpositae. La mayoría de los tipos polínicos estudiados tienen sus máximos diarios en primavera, estación del año con mayor concentración polínica en el sur de Europa, excepto Eucalyptus, Castanea, Parkinsonia y Cannabis, que generalmente lo tienen en verano, y que alcanzaron máximos históricos relevantes: Eucalyptus en 1994 (112 granos/111 3), Castanea en 1997 (233 granos/m 3), Cannabis en 1998 (28 granos/m 3).Palabras clave. Acrobiología, polen, verano, turismo, alergia, Málaga, sur de España.ABSTRACT. Analysis of the summer airborne pollen contera in the province of Malaga. In this work, a study about the atmospheric pollen content during the period July-September has been carried out in the province of Malaga. The study was made taking the data obtained during the last years in several localities of the province: Malaga (1992-1999), Estepona (1995-1997), Antequera (1998-1999) and Nerja (2000). In general, just between 3 and 6% of the annual total pollen were collected during those three months, the airborne pollen spectrum being represented by 14 pollen types: Eucalyptus, Castanea, Parkinsonia, Cannabis, Apiaceae, Ligustrum,Chenopodiaceae-Amaranthaceae, Palmae, Compositae, Artemisia,Typha, Cyperaceae, Poaceae y Urticaceae. During the period studied, the pollen types that reached highest concentrations were Eucalyptus, Chenopodiaceae-Amaranthaceae and Poaceae while the rest of the cited taxa were detected at very low concentrations. Some taxa present higher concentrations at determined sampling stations: Costana(' and Compositae in Antequera, Palmae and Parkin.s. onia in Malaga, and Artemisia in Ncrja. The evolution along the summer season shows, in general, two trends. The first one, in which the pollen concentrations are decreasing from July to August, is present in all the taxa and localities studied, except in Artemisia and Palmae. The other one, in which the pollen concentrations lightly increase from August to September, is present in the former two pollen types but also in Chenopodiaceae- Amarantliaceae and Compositae. Most of the pollen types studied reach their maximum daily peaks in spring (season in which the pollen concentrations are highest in southern Europe) except Eucalyptus, Castanea, Parkinsonia and Cannabis, that generally presented them in summer. These taxa reached notable maximum daily concentrations values: Eucalyptus in 1994 (112 grains/m 3), Castanea in 1997 (233 grains/ in3), Cannabis in 1998 (28 grains/m 3).Key words. Aerobiology, pollen, summer, tourism, allergy, Malaga, southern Spain.

scholarly journals Analysis of allergenic pollen data, focusing on a pollen load threshold statement

Aerobiologia ◽  
2021 ◽  
Author(s):  
Laura Šukienė ◽  
Ingrida Šaulienė ◽  
Rūta Dubakienė ◽  
Odilija Rudzevičienė ◽  
Gintautas Daunys
Keyword(s):  
Pollen Season ◽  
Airborne Pollen ◽  
Epidemiological Studies ◽  
Allergenic Pollen ◽  
Pollen Load ◽  
Pollen Data ◽  
Main Pollen Season ◽  
Pollen Types ◽  
Pollen Concentrations ◽  
Morbidity Data

AbstractAirborne allergenic pollen affects a significant part of the population and the information on pollen load is a valuable tool for public health prevention. The messages should be provided in a form easily understandable for the population. The study provides new insight for the categorisation of pollen load by defining thresholds solely from aerobiological data. Using the long-term airborne pollen data of Corylus, Alnus, Betula, Poaceae, and Artemisia have been evaluated the regionality of pollen concentrations in Lithuania. SPIn and peak values of the main pollen season highlighted as regionality indicators. The largest differences between stations were found in the cases of Corylus and Artemisia.The principle enabling a group of pollen concentrations into levels has been analysed based on retrospective aerobiological data of five pollen types. Thresholds were determined by employing the lowest peak value of the pollen season and applying the 25% principle for selected pollen types. The results were verified by performing associations of defined thresholds with retrospective morbidity data of allergic rhinitis and allergic asthma in Lithuania. Determined pollen thresholds can be used in epidemiological studies requiring associations with pollen concentration. Thresholds could also complement air quality information by integrating pollen load data into public messages or contribute to the development of mHealth systems.

scholarly journals Changes in the concentration of pollen over an 11-year period in a Polish urban environment

2016 ◽  
Vol 69 (4) ◽  
Author(s):  
Barbara Majkowska-Wojciechowska ◽  
Zofia Balwierz ◽  
Marek L. Kowalski
Keyword(s):  
Airborne Pollen ◽  
Allergenic Pollen ◽  
Reproductive Systems ◽  
Atmospheric Air ◽  
Qualitative And Quantitative ◽  
Pollen Concentrations ◽  
Poaceae Pollen ◽  
Dynamic Concentration ◽  
The City

Recent studies suggest that climate change can influence plant reproductive systems and have an impact on the increase in allergenic pollen in atmospheric air; highly allergenic pollen may intensify the allergic response in people. The aim of our study was to evaluate the seasonal dynamic concentration of the most allergenic pollen taxa, i.e., the following trees: <em>Alnus</em>, <em>Corylus</em>, <em>Betula</em>, and herbaceous plants: grasses (Poaceae), <em>Artemisia</em>, and <em>Ambrosia</em>, in the long-term period of 2003–2013 in the city of Lodz, Poland. Weekly airborne pollen concentrations were evaluated with a volumetric Lansoni pollen trap. The beginning and the end of the season were calculated by the 98% method. The birch (<em>Betula</em>) pollen was at the highest level and accounted for 79%, followed by alder (<em>Alnus</em>) – 19%, and hazel (<em>Corylus</em>) – 2%. Among the herbaceous taxa, grasses (Poaceae) pollen dominated – 79%, followed by mugwort (<em>Artemisia</em>) – 18%, and ragweed (<em>Ambrosia</em>) – 3%. Our findings indicate a lack of qualitative and quantitative change in the pollen produced over the 11-year period.

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