Aerobiology in alpine environments: Exploring pollen biodiversity and its impacts on human health

This review summarizes methods and relevant outcomes of aerobiological studies carried out in the alpine biome worldwide impacting the knowledge on the occurrence of airborne pollen and their origin, for biodiversity studies, models of transport, forecasts, and climate change scenarios, for the reconstruction of past vegetation, and the potential impacts on human health. Deposition sampling is the method of choice, while volumetric sampling is mostly performed in densely populated mountain ranges. Conventional microscopic identification of pollen of alpine environments is rarely complemented or replaced by molecular methods. The pollen bioaerosol mirrors the surrounding vegetation but includes components from medium and distant source locations. However, there is no uniform understanding on the definition of source-scales - crucial for the interpretation of the bioaerosol constituents - to which we propose an answer. Alpine habitats, with their cold-adapted plant communities, may react to increasing temperatures with shifts in their range. The potential of using pollen as a proxy to monitor such changes in alpine biomes has been exploited in paleoecology but rarely in aerobiology. Health impacts are linked to the low allergen load in the bioaerosol and the overall effect of the alpine climate in a highly natural environment. Generally, the soothing effect is reported for respiratory allergy patients, which may be jeopardized by seasonality and allergens transported from outside. The complex topography of mountain ranges does not allow for general assumptions on the quality and quantity of bioaerosol in alpine environments. We emphasize the importance of monitoring the bioaerosol in alpine environments to evaluate the effects of global change, and to optimize the management of respiratory health issues.