Pollen season has begun – and it is starting earlier and earlier with each passing year. Due to climate change, we see plant species thriving in our part of the world that are not native here. With serious consequences for millions of allergy sufferers in Germany alone. This is because allergies are not only a very common chronic disease worldwide, they are also still on the rise: 30 percent of all people in Europe suffer from an allergy – most of them from pollen allergy.
The impact of allergic diseases is severe. Year after year. The economic damage in the EU – which could have been avoided through correct treatment – amounts to around 100 billion euros. Around 30,000 young people nationwide drop out of their education because of an allergy and every tenth sick leave in Germany is due to an allergy. Schoolchildren with untreated hay fever have a 40 percent chance of dropping a whole grade in school during the pollen season. Approximately every sixth child suffers from an allergic disease. Allergies are therefore also among the most common chronic diseases in children. Children whose parents are also affected by allergies have a particularly high risk of allergic diseases: if one parent suffers from an allergy, the child’s risk of developing an allergy is 20 to 40 percent. If both parents have the same allergy, the child’s risk even increases to 60 to 80 percent. Yet, only ten percent of people with allergies are treated correctly, even though there are reliable and effective treatment options.
POLLEN LEVELS IN GERMANY: WHAT HAPPENED IN RECENT YEARS
In the spring months, the pollen of hazel, alder and birch cause hay fever and pollen asthma and determine the severity of the allergic symptoms. Since 2018, hazelnut pollen has been appearing in rising concentrations throughout Germany – this was also the case in 2022. Alder pollen has diminished slightly in 2022, after sweeping through Germany at unprecedented levels in 2021 and 2019: “These were really very intense alder years,” explains Professor Karl-Christian Bergmann, Chairman of the German Pollen Information Service Foundation – PID. “So the alders have been “resting” for the past year and now we are waiting with bated breath to see what happens in 2023,” Bergmann continues.
Birch pollen, along with grass pollen, are the most common types of pollen that cause hay fever, asthma and intolerance to pome and stone fruits (oral allergy syndrome). In 2022, there was an increase in birch pollen levels compared to previous years. Overall, therefore, 2022 was a pronounced “tree pollen year”. Beech, oak, pine and spruce also released large amounts of pollen compared to previous years, although pollen from pine and spruce does not cause allergies.
Grass pollen concentrations have been rising steadily since 2019 and reached a new peak in 2022. These pollens have been shown to cause inflammation of the mucous membranes in the respiratory tract. Pollen triggers the production of IgE antibodies in affected individuals, who are then considered “sensitised” and thus become more prone to developing hay fever and pollen asthma. Interestingly, people in big cities become sensitised to tree and grass pollen more often than those living in small towns or villages.
A new study has now shown  that air pollutants – and in particular particulates and nitrogen oxides – chemically alter the allergens in birch pollen, causing the allergens to become even more allergenic. “The higher rate of sensitisation to pollen in air-polluted environments can therefore be seen as a consequence of both the effect of air pollutants on plants and their pollen, but also of increased hypersensitivity of mucous membranes of people living in cities,” Bergmann emphasises.
In addition to increased allergenicity of pollen, inflammation of the mucous membranes due to air pollutants also changes, causing those affected to have increased symptoms of itching of the nose and eyes, reddening of the eyes, runny nose and asthma symptoms.
POLLEN COUNTS IN GERMANY: STATUS QUO AND FORECAST 2023
It has almost come to the point where the time when the first pollen of the new pollen season appears overlaps with the time when the last pollen of the previous pollen season disappears. On the one hand, climate change causes the pollen of grasses and herbs to persist longer into autumn, while on the other hand, trees begin to flower earlier in the year. Most affected are people allergic to hazel and alder pollen. Hazels and alders are extremely sensitive to temperature and begin to flower during prolonged mild phases during the winter months. In the wake of climate change, these mild phases are occurring more frequently in Germany and the temperatures reached are also higher than in the past, as the record high temperatures at the turn of the year 2022/2023 clearly showed. Where in the past, temperatures barely reached 10 °C under similar weather conditions, today they can quickly reach 15 °C and more. The pollen of the early-flowering tree species is released correspondingly quickly and early in the year.
The 2023 pollen season in the southwest of Germany began on the very first day of the year with record-breaking pollen concentrations and in some places already high hazel pollen counts – a first in measurement history. This trend towards early pollen exposure is reinforced by the new planting of allergenic tree species in cities, including, for example, the non-native and climatically hardy purple alder, which tends to release its pollen as early as around Christmas time, weeks before the native alders.
The PID Foundation therefore recommends allergy-friendly planting in cities, avoiding trees that release allergenic pollen. After this year’s jump-start to the pollen season, the lower temperatures since mid-January have somewhat reduced the pollen count. In the west and south, however, the alder pollen season has already begun. How high the levels will be in February depends very much on the weather conditions. Sunshine and temperatures above 10 °C are almost certain to bring high alder pollen concentrations at this time of year.
HOW ARE POLLEN FORECASTS MADE?
In Germany, almost one in seven adults suffers from a medically diagnosed allergy, with pollen being one of the most common triggers. A simple but effective treatment for pollen allergies is to reduce or avoid allergen contact. The pollen forecast is particularly suitable for this purpose.
In Germany, the concentration of pollen in the outdoor air has been monitored since 1983 by the measuring stations in the network of the German Pollen Information Service (PID) foundation. The PID supports pollen allergy sufferers and physicians by providing pollen forecasts and information, thereby making an important contribution to allergy prevention.
For decades, part of the measurement data obtained has formed one of the bases for the German Weather Service’s (DWD) daily graphical pollen load forecast for eight allergy-relevant pollen species, the so-called Pollen Danger Index .
In addition, the PID has been providing weekly pollen forecasts for Germany since 2016 that not only cover an extensive spectrum of pollen, but also some allergologically relevant mould spores and represent an important supplement to the DWD forecasts. Beyond the measured pollen data from the PID monitoring network, other building blocks are needed to make a reliable prediction. Predicting pollen levels requires, for example, knowledge of the stage of development of the plants, knowledge of the release of pollen at this stage of development and knowledge of the probable weather development. More pollen from the developed plant is released when the days are warm, sunny and windy; less pollen is released when it is cold and wet. Pollen data from previous years, as well as pollen count forecasting models for specific species, are also available for reference. In order to bring all this information together in a meaningful way, expert knowledge from the fields of aerobiology, botany and allergology must also be taken into account, which then enables a reliable prediction to be made . The PID weekly pollen forecast is available free of charge on the website https://www.pollenstiftung.de/ and in the PID newsletter.
It is generally advisable to find out what data a particular pollen forecast is based on before using or recommending it (on the internet, as an app, etc.).
NEW POLLEN COUNT CALENDAR 5.0
The pollen count calendar provides information on the general pollen count of a selection of pollen species common in Germany, including allergologically relevant species such as birch and grasses. However, it also includes less relevant species such as poplar or pine. The information is based on the measurement data of the pollen measurement network of the German Pollen Information Service Foundation over a period of six years. The new calendar 5.0 includes data from 2016 to 2021, replacing the previous calendar 4.0, which covered the years 2011 to 2016.
The rapidly progressing global warming not only affects us humans, but also the plants that grow here. Plants clearly react to the change that has already occurred, especially to the increase in air temperature. Over time, not only the amount of pollen changes, but also in particular the occurrence of pollen in the course of the year. There is often a gradual shift forward in the flowering period of the plants concerned, which also shifts the period of pollen exposure over the years. Older pollen calendars must therefore be replaced regularly with new calendars that reflect the current trend.
The maximum pollen exposure takes place during the main flowering period, during which 80 percent of the average annual amount of the respective pollen species is airborne. Based on the measurement data, we can show that this important stage of the pollen season has once again changed significantly for some pollen species in the new, updated version of the calendar compared to the previous calendar. Alders have been flowering a whole nine days earlier than usual. This already starts around 13 February instead of 22 February as before.
As far as birches are concerned, the start of the main flowering period has shifted forward by two days compared to the previous calendar, and by as much as six days compared to the first years of the 21st century. Grasses and herbs react less sensitively overall, taking flight in essentially the same period as before. Major changes here mainly concern the periods of pre- and post-blooming. More specifically, the first grass and herb pollen of the season is released earlier, while the late pollen is released later than a few years ago.
Apart from the current pollen forecast, the pollen calendar remains one of the important and well-known tools for pollen allergy sufferers and their treating physicians when it comes to orientation and prevention during the pollen season.
GOOD AIR QUALITY, HEALTHY URBAN PLANTING – ALLERGY-FRIENDLY LIVING?
Allergies are the most common chronic disease worldwide. “Deaths from the effects of insect venom or food allergy occur time and again. Nevertheless, allergies are still often trivialised and downplayed,” says Professor Torsten Zuberbier, Chairman of the European Centre for Allergy Research Foundation (ECARF). “However, allergies can now be treated very effectively, and in most cases it is possible to eliminate symptoms with modern medications,” Zuberbier continues. In addition, it is possible to integrate strategies not based on pharmaceuticals into the treatment concept. Air purifiers that filter not only pollen but also particulate matter provide helpful support for those affected – especially in urban areas. Modern apps are also available: They help people with respiratory allergies to adjust their medication in time and people with food or contact allergies to detect their allergens early using modern photo technology on packaging [5, 6].
In the meantime, there are comprehensive concepts for allergy-friendly living within the framework of the ECARF Foundation’s work – ideally, this is already taken into account in the planning or furnishing of a building.
Allergenic substances lurk everywhere – in wall paints, carpets, adhesives, ventilation systems and even outdoors. This is a problem that allergy sufferers are confronted with every day, because after all, people spend around 90 percent of their time indoors. And it is precisely there that the level of contamination is 30 times higher than outdoors. “We must look at allergies in the context of buildings. In collaboration with ECARF, we have developed a globally unique process on how to construct and renovate buildings in an allergy-friendly way. For the first time, project developers now have the opportunity to minimise allergy triggers during the construction or renovation of a building,” says Angela Balatoni, Managing Director of AFBA.
Another challenge is climate change, which prolongs the pollen season . There is also evidence that the increase in air pollutants such as ozone and particulate matter associated with climate change can alter the composition of pollen and make it more aggressive. In the immediate vicinity of roads, CO2 emissions from internal combustion engines have the same effect as fertiliser. “It has also been shown that pollen counts increase in direct proximity to busy roads. Urban planners, but also landscape architects, need to address these issues,” Balatoni demands.
“It would be a dream come true for us to support Berlin on its way to becoming an allergy-friendly capital,” says Torsten Zuberbier. “It makes sense to have a lot of greenery in the city – but planting pollen emitters like birch trees should be avoided at all costs,” Zuberbier continues. There are also additional initiatives by the ECARF Foundation, such as how to raise awareness already at school level. “A child performing worse at school because of untreated hay fever, not being able to participate in sports lessons because of its untreated asthma – that should no longer happen!”
 Stawoska I., Myszkowska D., Oliwa J., Skoczowski A., Wesełucha-Birczyńska A., Saja-Garbarz D., Ziemianin M. Air pollution in the places of Betula pendula growth and development changes the physicochemical properties and the main allergen content of its pollen. PLoS One. 2023 Jan 25;18(1):e0279826
 https://pubmed.ncbi.nlm.nih.gov/35292649 / https://pubmed.ncbi.nlm.nih.gov/36473873/.
The non-profit European Centre for Allergy Research Foundation (ECARF) has been certifying products and services with the ECARF Seal of Quality, the only Europe-wide certificate for allergy-friendly products and services, on the basis of scientific quality criteria since 2006. Furthermore, ECARF specifically supports allergological research at the European level as well as initiatives to improve the medical treatment of allergic diseases. ecarf.org
The non-profit foundation German Pollen Information Service (PID) has been operating the only nationwide measurement network of uniform pollen traps for the detection of airborne allergenic pollen since 1983, using a measurement method that has been standardised throughout Europe since 2019 (EN 16868:2019). This means that the PID is the only source of detailed chronological documentation on the occurrence of climate change-induced changes in the type and concentration of allergenic pollen of trees, grasses and herbs in Germany. The measured pollen data serve, among other things, as the basis for the nationwide pollen forecasts of the PID and the German Weather Service. pollenstiftung.de
The Allergy Friendly Buildings Alliance GmbH (AFBA) supports the building industry in developing allergy-friendly buildings with the aim of improving the well-being of people in buildings. In cooperation with the ECARF Foundation, AFBA is a partner of the building industry at the interface with university medicine. afba.de