Not Just a Sneeze: Pollen Increase Blood Pressure

It is estimated that around 20% of adults globally are allergic to pollen. Pollen allergies, a specific type of allergic rhinitis, can go beyond the typical itching eyes and frequent sneezing and for instance cause asthma through systemic inflammation. Researchers have also suspected that pollen may have an impact on cardiovascular health, but evidence was lacking.

Effect on blood pressure

For the first time, scientists from Swiss TPH have now been able to establish a link between pollen exposure and blood pressure. In a study published today in the peer-reviewed journal Environmental Research, they found that during periods with very high pollen concentrations, systolic and diastolic blood pressure increased on average by 2.0 mmHg and 1.5 mmHg respectively, compared to no-pollen days. Blood pressure effects were already evident at small pollen concentrations and continuously increased with increasing pollen in the air. The effect was markedly stronger for women and people with a high body-mass index.

Significant public health burden

“Even if this is a rather small average effect on blood pressure, it may cause a substantial burden for public health given the large population it affects,” said Alexandra Bürgler, PhD candidate at Swiss TPH and first author of the study. “Other studies have indicated a link between high pollen concentration and rising hospitalisations. Our results now add to this mounting evidence and highlight that pollen allergy is a growing public health problem.”

Earlier studies have shown that climate change has led to a longer and more intense pollen season in Switzerland and throughout Europe. Also, the proportion of the allergic population has increased over the past decades.

Study participants from the Basel region

To establish the link between pollen exposure and blood pressure, the researchers studied 396 adults from the Basel region in Switzerland, 302 of whom reported having a pollen allergy. All participants measured blood pressure repeatedly during the pollen seasons of 2021 and 2022.

The researchers also analysed the sensitisation of participants to different pollen such as grasses, birch and hazel using a skin prick test. Though allergic people perceive the most severe symptoms in the grass pollen season, the effect on blood pressure was not noticeably different for tree pollen and grass pollen.

Policy implications

“Pollen allergies and high blood pressure are two of the most common chronic diseases in Europe – it was about time to investigate how they are related,” said Marloes Eeftens, Principal Investigator and Group Leader at Swiss TPH. “It is important that the evidence we built can now inform policy, for example when it comes to urban planning and biodiversity. Trees in the city is important for shade – in particular in view of climate change – but there might be better options than highly allergenic birch trees. Thus, it is important that the health effects of allergenic trees receive higher priority in future urban city planning.”

About the study

The study is part of the EPOCHAL project, which aims to find out how pollen from trees, grasses and herbs affect the health of the population in Switzerland. EPOCHAL has received funding from the European Research Council (ERC) and is further supported by the Swiss National Science Foundation (SNSF).