Abstract
Summary Background Globally, climate change is being observed. Pollen allergies have been increasing since the middle of the last century. Outdoors, sensitization against pollen allergens is responsible for the highest prevalence of allergies of eyes and airways. Hence, the following two questions arose: (1) How does climate change become manifest locally–regionally, and do temperatures and precipitation have to be considered exceptional in 2018? (2) How do changing meteorological conditions impact on pollination and pollen load? Methods Pollen data of the main allergenic plants—collected at the pollen monitoring station Linz, Upper Austria—were analysed; 2018 was compared to the years 1993–2017. By means of statistical methods, the impact of meteorological parameters on pollen seasons and pollen load were examined. Results Climate change was confirmed for the region. The regional climate has shifted from moderate to warmer and drier (semi-arid) conditions. Preseasonal cumulated meteorological parameters determined flowering and pollen seasons (PS). Start and duration of the pollination of hazel, alder, birch, and grass followed other rules than the seasonal pollen production, termed seasonal pollen integral (SPIn). By its hybrid character, the model-year 2018 offered the unique chance to generate and explain different scenarios of pollen emission and transmission. For the start of flowering of hazel (Corylus), alder (Alnus) and birch (Betula), the coincidence of cumulated mean daily warmth (MDWcumul) and a distinct threshold for the highest temperature of a day (HTD) is necessary and species-specific. In 2018, the earliest begin of the pollen season (PSB) was observed. Frost delayed the PSB. Preseasonal frost as well as cool temperatures caused SPIn of alder and birch to rise, whereas SPIn of hazel were increased by warmer temperatures. Warm weather prolonged pollen seasons of early flowering plants. Heat combined with drought shortened PS of birch in 2018. Cumulated relative humidity (RHcumul) correlated highly significant with the PSB of grasses. Warm and dry conditions in 2018 caused the earliest PSB of grass since 1993. Over the years, SPI and major pollen peaks of grasses have decreased, primarily due to dryness. Conclusion The assumption that climate warming in Linz over 26 years should have increased pollen concentrations of allergenic plants was not confirmed. On the contrary, trend analyses showed that the pollen load has decreased. Hence, the increase in sensitization to pollen allergens and of the prevalence of pollen allergies ask for other explanations.
Highlights
Pollen are among the most important allergen carriers outdoors
96 How will climate change alter the dynamics of airborne pollen and pollen load of allergenic plants?
How will climate change alter the dynamics of airborne pollen and pollen load of allergenic plants? 97
Summary
Pollen are among the most important allergen carriers outdoors. In Austria at least in children, sensitization and aero-allergies depend on the pollen load [1]. In Salzburg, 53.5% out of 501 unselected teens at an age between 12 and 21 were found to be sensitized against pollen allergens, 26% against Phl p 1 (grass allergen group 1) and 16.3% against Bet v 1 (main allergen of birch). Because of global warming, accelerated at least since 1980, and an increase in CO2 in the air from about 300 to 400 ppm (parts per million) over the past century, an increased pollen load is expected by some scientists [4]. The warm and dry “model year 2018” was compared to the regional weather conditions over the past 25 years. Studying their meteorological impact on pollen counts of alder, hazel, birch and grasses should have enabled us to evaluate recent hypotheses on pollination
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