Hatschi – pollen season 2024

Grass pollen season now in full swing

After the cooler phase in the second half of April, the friendly and warm weather at the end of April and beginning of May has ensured that grass pollen is now blooming widely at low altitudes and reaching high concentrations in friendly and dry weather (see Fig. 1).

Grass pollen causes by far the most allergic symptoms, with around 15% of the population suffering from grass-related hay fever. The wind-pollinated grasses, which are often found in large quantities in meadows, produce enormous quantities of pollen to ensure pollination; a single blade of grass contains around four million pollen, and in the case of rye it is as much as seven million! The light and very small grass pollen is spread over long distances (sometimes dozens of kilometers). This makes it clear that it is difficult to avoid grass pollen, as it is dispersed up to the highest mountain altitudes.

Early grass pollen flight

By mid-April, the vegetation was two to four weeks ahead of the long-term average due to significantly above-average temperatures since the second half of January. This meant that the grasses also developed very early, but were halted somewhat by the cold snap in mid-April. With the warm weather towards the end of April, the grasses at low altitudes really got going, still with a lead of around two weeks.

Long grass pollen season

The grass pollen season lasts until late summer and usually peaks in the second half of May and in June (see Fig. 2), meaning that allergy sufferers have a very long time to suffer. From mid-August onwards, the pollen count gradually decreases, although some grasses continue to flower into November, but in the fall the pollen concentrations in the air are only low.

Avoidance still possible over Ascension Day and Whitsun

However, it is still possible to escape the grass pollen over Ascension Day and Whitsun - you just have to go high enough. From around 800 to 1000 meters, the grasses are not yet in bloom; only the long-distance flight causes a certain amount of exposure, but this is still very low from around 1500 meters. Even if the zone of flowering grasses shifts slightly upwards by Whitsun, the grass pollen can still be largely avoided if you go to altitudes of around 1500 meters and higher. In June, it is hardly possible to avoid the higher altitudes when the grasses are also in bloom on alpine meadows and alpine lawns. Then the situation can even be reversed and grass pollen concentrations can be higher at high altitudes than at low altitudes, where mowing also ensures a certain reduction in grass pollen.

Further course of the grass pollen season

How the grass pollen season continues is influenced by the weather and cannot be predicted. The decisive factor is how often it rains and how long the sunny phases with high concentrations last.

Grass pollen and climate change - more complaints

Increasing warming in combination with increased CO2 levels (natural fertilizer effect) has been shown to change the intensity and timing of grass flowering, causing a shift and lengthening of the growing season and an increase in biomass. The start of the pollen flight is earlier, and at the same time the pollen season lasts longer due to higher temperatures in the fall. This means that, on average, there is more grass pollen in the air for longer. Another unfavorable effect will be that although there tends to be more precipitation with higher temperatures, it will be distributed differently. The dry phases are likely to be longer, while heavier precipitation is expected for short periods. This in turn means that the pollen will be washed out less frequently and therefore the pollen concentration will be reduced less often. All in all, not a rosy outlook for grass pollen allergy sufferers! More information on grass pollen and climate change can be found here.

Birch pollen count falling in the central plateau

The highly allergenic birch trees have largely faded at low altitudes, meaning that pollen concentrations are decreasing somewhat. On the other hand, birch trees are flowering at medium and higher altitudes, meaning that the pollen load is sometimes high here in friendly and dry weather. The situation is therefore exactly the opposite: while grass pollen allergy sufferers should move to higher altitudes over the next few days and weeks for relief, it is advantageous for birch pollen allergy sufferers to stay at lower altitudes.

Currently also oak and plane tree blossom

At the moment, there is not only a lot of birch and ash pollen in the air, the oaks and plane trees are also currently in bloom and usually bring weak to moderate pollen levels. However, their pollen is not very allergenic, so the symptoms remain manageable.

Conifers starting to flower

The flowering season of pine trees (pines, firs, spruces) has also begun. Their large pollen is sometimes found in large quantities in the air and can cause yellow coatings on surfaces and, similar to Sahara dust, can be deposited on cars, for example, forming a yellowish film. The flowering conifers can produce pollen clouds that are clearly visible when the wind picks up (see Fig. 1). However, their large pollen is hardly allergenic.

Grass pollen bloom is imminent

The meadows at low altitudes are lush green, the first grasses have formed inflorescences, which will soon scatter pollen (see Fig. 2), the grass pollen season and thus the main time of suffering for allergy sufferers is about to begin.

 

Lots of birch pollen in the north over Easter

Birch trees are currently in full bloom much earlier than the long-term average, with birch pollen causing many hay fever problems for allergy sufferers (see Fig. 1). High concentrations of birch pollen are to be expected over the Easter period, especially in the east, with the exception of medium and high altitudes. In the south, however, the cloudy and wet weather means that there is hardly any pollen and therefore no birch pollen in the air.

In the next few weeks, we can expect a high concentration of birch pollen if the weather is friendly, mild and dry. In addition, the pollen concentrations this year are significantly higher than last year, as this year is a birch mast year. As usual, however, the actual pollen concentrations will depend on how the weather develops.

The grasses will soon start to flower

It won't be long before the grasses , which cause by far the most pollen allergies, start to bloom, and much earlier than the long-term average. The grass pollen season then lasts a very long time until the beginning of fall.

Current Ash blossom

The pollen season continues to make great strides with the clearly above-average temperatures in March (see here). At the moment, ash trees, which produce moderately allergenic pollen, are flowering at low altitudes (see Fig. 1), while there is usually only a little hazel and alder pollen in the air.

Ash pollen concentrations are currently moderate in the north and sometimes high in the south. Incidentally, just under 10% of people in Switzerland suffer from an ash pollen allergy.

The common ash tree (Fraxinus excelsior), which is by far the most widespread in Switzerland, has been suffering greatly for a few years from a fungus originating from East Asia, which causes ash dieback or ash wilt. This fungus continues to spread, with young trees in particular dying in large numbers after infection. Meanwhile, older trees die slowly over several years. As a result, the area of ash trees in Switzerland has been significantly decimated in recent years, which has also led to a certain decline in the concentration of pollen.

Attention ash pollen allergy sufferers!

As ash trees belong to the olive family, people who are allergic to ash can also be allergic to other olive trees. These include forsythia, which is currently flowering in many gardens (see Fig. 2), as well as lilac, jasmine, privet and broom, which flower later. However, these trees and shrubs produce significantly less and also less aggressive pollen. The olive tree family also includes olives, which produce a lot of aggressive pollen. As the climate becomes milder and milder, olives will continue to thrive in Switzerland and it is conceivable that olive cultivation will also begin in Switzerland in the future. This would make the situation much worse for people with allergies to olive tree pollen.

Soon birch blossom

In the mildest areas, the first birch trees have already started to blossom. Birch pollen is the most allergenic type of pollen among the trees and, together with the grasses that start to bloom later, causes the most hay fever problems. At least 20% of the Swiss population suffers from a birch pollen allergy! With the very mild weather until Friday, the development of the birch catkins is progressing further and birch pollen must be increasingly expected in the air at low altitudes (see Fig. 2).

At the weekend and at the beginning of next week, further development will be slowed down somewhat, especially in the north, by lower temperatures. Before Easter, however, there are signs of a significant moderation, so that an acceleration of the development can be expected again. In the event of friendly and dry weather at Easter (development still very unclear), high concentrations of birch pollen are to be expected at low altitudes, resulting in widespread red eyes and runny noses for allergy sufferers.

Hazel pollen season soon to end in the swiss plateau

Compared to the average from 1991-2020, the hazel blossom had a clear head start of around three weeks in the swiss plateau this year. At altitudes above around 800 meters, the hazelnuts even bloomed about a month earlier than normal due to the record mild February. The advantage of the exceptionally mild weather is that the hazel blossom is now slowly coming to an end earlier than usual in the lowlands and the pollen concentrations are only weak to moderate, even in friendly and dry weather. At slightly higher altitudes, however, the hazel pollen bloom is still continuing.

Alder still in bloom

The situation is currently different for the other allergenic tree early bloomer, the alder. It is still in full bloom, which means that pollen concentrations are often high in dry weather. This is likely to remain the case for at least another week.

Other pollen currently in the air

Other, less allergenic types of pollen can also be found at the moment, in particular yew, poplar and elm. There is also pollen from cypress trees in the air.

Ash blossom starts soon

The allergenic ash trees are also starting to bloom much earlier than the long-term average. The first ash pollen can already be found in Ticino, on Lake Geneva and in the Basel region. In about one to two weeks, the highly allergenic birch trees will join them. This means there is hardly any respite for allergy sufferers...

Currently already a moderate amount to a lot of hazel pollen and the first alder pollen

At the moment, more and more people are experiencing red, watery eyes, sneezing fits and a runny nose, an unmistakable sign that the pollen season has begun. It is noticeable that allergy sufferers are particularly sensitive to pollen at the beginning of the season. This is probably due to the fact that, on the one hand, the immune system is not yet as well prepared after the winter months and, on the other hand, the pollen has more allergens at the beginning of the season than towards the end. After an average to slightly below-average temperature in the north in the first half of January, the pollen season in the north started later this year than last year, when hazel pollen was already blooming more strongly in the first half of January due to the exceptionally mild weather. With temperatures mostly above average for more than a week, the hazelnuts have now also awoken from their winter hibernation this year and are already flowering quite strongly, so that the hazel pollen load at low altitudes is currently already moderate to strong (see Fig. 1).

At medium altitudes, the hazel pollen concentration is still low. In addition, the first alders are already blooming, with alder pollen counts in the Swiss Plateau currently low to moderate (see also pollenundallergie.ch). In the south, hazel and alder have already started to bloom in the first half of January due to significantly above-average temperatures; the hazel pollen count here is already high and the alder pollen count is moderate.

Pollen calendar

The following pollen calendar (Fig. 2) provides an overview of the most important allergenic plants in Switzerland, the flight time of their pollen and their allergy potential.

It can be seen that the flowering of hazelnuts and alders often begins in the first half of January and is at its peak during February. In this respect, the development this year is quite normal. However, the development can also be abruptly halted if there are repeated cold setbacks. On the contrary, after some rain in the north on Thursday and thus the washing out of the pollen, there will be a longer-lasting phase of high pressure with above-average temperatures (for the weather development in the coming days, see here), so that the load of hazel and alder pollen will quickly increase again to moderate to high. In the south, it will remain dry on Thursday with quite sunny weather, so there will be no temporary decrease in pollen count here and it will therefore remain high in places. The current organic weather for your location can be found on our homepage (search for location, then click on organic weather). Here, for example, you can find the current pollen count for Zurich.

Tips for reducing the pollen count

Around 20% of people in Switzerland are affected by a pollen allergy, and the trend is rising. A few measures can help to reduce the pollen count and thus the symptoms. The following is a non-exhaustive overview of some of these precautions.

• Preventive medication using antihistamines, which are available from pharmacies as nasal sprays, eye drops or tablets.
• To relieve symptoms, rinse pollen out of the nose (nasal showers), treat red, itchy eyes with cold compresses or a damp washcloth.
• On days of high pollen count, spend as little time as possible outdoors.
• Change clothes after spending time outdoors (not in the bedroom area).
• Do not dry laundry outdoors.
• Install pollen screens in front of the windows.
• Wash your hair in the evening or brush it out thoroughly so that the pollen is not spread on the pillow.
• Wear sunglasses (ideally with side shields). They keep the pollen away from the eyes and protect their mucous membranes, which are particularly sensitive to light during the pollen season.
• A protective mask is recommended on pollen-intensive days.
• Vacuum floors, upholstered furniture and carpets thoroughly on a regular basis. We recommend vacuum cleaners with HEPA filters, which also remove tiny suspended particles from the air.
• Set up an air purifier. These devices filter pollen and dust out of the air and can provide relief.
• Regularly maintain and replace pollen filters in the car.

Increasing problems with pollen in the future

Pollen will cause more and more problems in the future. The pollen season is getting longer and longer, it starts earlier and lasts longer and longer in the fall due to immigrant plants such as ragweed. Allergy sufferers therefore have an ever shorter rest period. Due to climate change and the resulting higher average temperatures, many plants are also producing more pollen. At the same time, the more frequent periods of drought mean extreme stress for the plants. After such years, they sometimes produce huge amounts of pollen, which leads to more allergies. In addition, the pollen often becomes more aggressive as a result of climate change. Under stress, plants ramp up their immune system and produce special proteins to protect them from negative environmental influences. People with a pollen allergy react particularly strongly to these proteins. Truly not a rosy outlook for pollen allergy sufferers...