Expert Comment: Pollen season has started in Switzerland

“As the pollen count is rising across Switzerland, many people are already feeling the effects. Right now, hazel and alder are releasing large quantities of pollen throughout the country. Other trees such as ash have started blooming as well. For the one in five individuals in Switzerland who suffer from hay fever, this marks the beginning of weeks of symptoms.

This is more than a seasonal inconvenience. Our research at Swiss TPH, in collaboration with MeteoSwiss, analysed pollen data across Switzerland over three decades. We found that for plants such as hazel or grasses, the pollen season now starts up to 25 days earlier than it did 30 years ago. Also, for many plants the trend points towards longer duration – for nettle and hemp plants, it has extended by up to 37 days. What we can say in general is that pollen concentrations have risen substantially, with beech and hazel doubling in intensity. These developments are fuelled by climate change: rising temperatures push the season to start earlier, increase pollen production and support the spread of new allergenic plant species.

Whether 2026 will prove to be an unusually intense pollen year remains an open question, but what we can say with certainty is that evidence points towards longer and more intense pollen seasons ahead.

What is also clear is that health effects go beyond sneezing. Our research has shown that high pollen concentrations are associated with an increase in blood pressure. Other studies have linked peak pollen periods to increased hospital admissions due to asthma attacks and to more cardiovascular events. Given how many people are affected, the public health burden is substantial.”