Abstract
Research Highlights: Daily airborne Cupressaceae pollen disruption ranged from 20 to 90%; relative humidity (RH), rainfall and atmospheric pressure (AtP) were the major meteorological determinants of this phenomenon. Background and Objectives: Cupressaceae family includes several species that are widely used as ornamental plants pollinating in late winter-early spring and might be responsible for allergic outbreaks. Cupressaceae pollen disruption may favour allergen dissemination, potentiating its allergenicity. The aim of this work was to characterize the Cupressaceae pollen aerobiology in Évora, South of Portugal, in 2017 and 2018, particularly the pollen disruption, and to identify the meteorological parameters contributing to this phenomenon. Materials and Methods: Pollen was collected using a Hirst type 7-day pollen trap and was identified following the standard methodology. Temperature, RH, rainfall, global solar radiation (Global Srad), AtP, wind speed and direction were obtained from a weather station installed side-by-side to the Hirst platform. Back trajectories (12-h) of air masses arriving at Évora were calculated using the HYSPLIT model. Results: Cupressaceae pollen index was higher in 2017 compared to 2018 (>5994 and 3175 pollen/m3, respectively) and 36 ± 19% (2017) and 64 ± 17% (2018) of the pollen was disrupted. Higher levels of disrupted pollen coincided with RH > 60% and rainfall. Temperature, Global Srad and AtP correlated negatively with pollen disruption. Wind speed and wind direction did not significantly correlate with pollen disruption. Intra-diurnal pollen pattern peaked between 9:00 am–2:00 pm, suggesting local origin, confirmed by the back trajectory analysis. Intra-diurnal pollen disruption profile followed hourly pollen pattern and it negatively correlated with AtP, temperature and Global Srad but was uncorrelated with RH. Conclusions: The results suggest that RH, rainfall and AtP are the main factors affecting airborne Cupressaceae pollen integrity and in conjunction with daily pollen concentration may be used to predict the risk of allergy outbreaks to this pollen type.
Highlights
IntroductionThe family includes 30 genera and 160 species distributed by temperate or temperate-warm regions of Northern and Southern Hemispheres, almost 3/4 of the species are present in the Northern hemisphere [1,3]
In this work we have investigated the disruption of Cupressaceae pollen in a realworld scenario, in the south of Portugal
Cupressaceae pollen, produced in large quantities (523 billion per plant) [38], are considered moderately allergenic [13] and because Cupressus species are widely used as ornamental plants, they are widely distributed in urban environments [15], being a common cause of winter allergy in urban environments [39], such as Évora, a middle-sized town situated in the South of Portugal
Summary
The family includes 30 genera and 160 species distributed by temperate or temperate-warm regions of Northern and Southern Hemispheres, almost 3/4 of the species are present in the Northern hemisphere [1,3]. They are coniferous and heliophiles plants, with medium size, and can grow up to 30 m maximum. Cupressaceae is the only family that shows a non-spiral arrangement of microsporophylls and each microsporophyll bears a variable number (2–6) of pollen bags [2] This family is distributed in all of Earth’s continents, except Antarctica. In Portugal, several species from the genera Juniperus and Cupressus are distributed throughout the continental territory, and Cryptomeria,
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