Climate change has many known effects on human health, and one of them has to do with the dreaded spring allergy season. Pollen concentrations are very sensitive to changes in temperature, and it appears that anthropogenic climate change changes spatially and temporally the amount of pollen in the air, with important consequences for the respiratory health of those who suffer from allergies and asthma. High temperatures cause flowering to start earlier, and high CO2 concentrations also result in higher pollen production.
In recent weeks, two new articles related to this problem have been published. The first refers to a study of pollen concentrations in North America between 1990 and 2018 and the results, which were published in February in the journal PNAS , indicate that in this interval the concentration of pollen in air has increased considerably and, in addition , that allergy seasons are getting longer. Using a set of climate models, the researchers demonstrated the important role of anthropogenic climate change in this effect. According to the authors, the spring allergy season would have lengthened up to twenty days in the last thirty years.
Long-distance pollen transport
The second study has used data from Germany and introduces a new variable: long-distance pollen transport and its influence on allergy season. Pollen is known to travel hundreds of kilometers, and with changing weather patterns, many people may be exposed to pollen from species that their bodies were not used to.
To collect data, the researchers chose six pollen monitoring stations in the Bavarian region, and found that for species such as hazel and alder, the pollen season was advanced by up to two days per year in the period from 1987 to 2017. Other species that usually flower later, such as birch and ash, advance their seasons by around half a day each year.
To differentiate between local pollen and transported pollen, the scientists studied preseason patterns. For example, if the monitoring stations detected birch pollen in the air, but the birch trees in the area had not yet bloomed, the pollen was considered to have come from another region. ” We were surprised that preseason pollen transport was a fairly common phenomenon that is observed in two-thirds of cases, ” explains Annette Menzel, Professor of Ecoclimatology at the Technical University of Munich. This variable can modify the estimates that only take into account local flowering to estimate the effect of climate change on the allergy season.
For the authors of the work, published in the journal Frontiers in Allergy, it is essential to include this factor in the predictions of future scenarios. What happens over long distances can have effects on local allergies, and to address the problem it is necessary to take into account changes in land use and vegetation cover , as all this affects patterns annual pollen and therefore human respiratory health.
