An estimated one-fifth of the world’s population is affected by pollen allergies. Researchers at Swiss TPH have now discovered that high pollen concentrations can increase blood pressure in allergy sufferers. Pollen allergies are thus becoming a growing public health problem, especially as the pollen season is becoming longer and more intense due to climate change. The research findings were published today in the journal Environmental Research.
It is estimated that around 20% of adults worldwide are allergic to pollen. Pollen allergies, a particular form of allergic rhinitis, can go beyond the typical itchy eyes and frequent sneezing and trigger asthma, for example, through systemic inflammation. Researchers have long suspected that pollen could also have an impact on cardiovascular disease, but so far there has been no proof.
Effect on blood pressure
Scientists at Swiss TPH have now been able to establish a link between pollen exposure and blood pressure for the first time. In a study published today in the journal Environmental Research, they show that systolic and diastolic blood pressure rose by 2.0 mmHg and 1.5 mmHg respectively during days with very high pollen concentrations. The effects on blood pressure were already observed at low pollen concentrations and increased continuously with increasing pollen concentrations in the air. The effect was significantly more pronounced in women and people with a high body mass index.
Significant burden on public health
"Even if it is a rather mild effect on blood pressure, it may represent a significant public health burden given the large population it affects," says Alexandra Bürgler, PhD student at Swiss TPH and first author of the study. "Other studies have indicated a link between high pollen concentrations and increasing hospitalizations. Our results add to the evidence that pollen allergies are a growing public health problem."
Previous studies have shown that climate change has led to a longer and more intense pollen season in Switzerland and throughout Europe. The proportion of the population with allergies has also increased in recent decades.
To establish the link between pollen exposure and blood pressure, the researchers examined 396 adults from the Basel region, 302 of whom reported having a pollen allergy. All participants had their blood pressure measured repeatedly during the 2021 and 2022 pollen season.
The researchers also analyzed the participants’ reaction to various pollens such as grass, birch and hazel using a skin prick test. Although allergy sufferers experience the strongest symptoms in the grass pollen season, the effect on blood pressure was not noticeably different from that of tree pollen.
Implications for policy
"Pollen allergies and high blood pressure are two of the most common chronic diseases in Europe. So it was time to investigate how they are linked," says Marloes Eeftens, study leader and group leader at Swiss TPH. "It is important that the insights we have gained can now be incorporated into policy, for example in relation to urban planning and biodiversity. Trees in the city are important to provide shade - especially in view of climate change - but there are alternatives to highly allergenic birch trees. It is therefore important that the health effects of allergenic trees are given greater consideration in urban planning in the future.
About the study
The study is part of the EPOCHAL project, which aims to evaluate how pollen from trees, grasses and herbs affects the health of the population in Switzerland. EPOCHAL was funded by the European Research Council (ERC) and is supported by the Swiss National Science Foundation (SNSF).
