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Seasonal allergies are becoming more intense and protracted due to climate change, according to a new study.
Warming conditions are lengthening pollen seasons around the world, researchers from the George Washington University School of Medicine and Health Sciences found.
The new paper builds on previous studies that link worsening allergies in Europe with climate change and elevated concentrations of CO2 in the atmosphere.
Climate change is bringing 19 extra days of pollen a year
The new research, published in the journal The Laryngoscope, examined studies from 2000 to 2023 to find data linking global warming with pollen production.
Sixteen studies identified a link between rising temperatures and extended pollen seasons.
Our changing climate is making plants shift the timings of their developmental stages, releasing the microscopic particles that enable reproduction earlier and for a longer period.
Some research predicted that total pollen production in the US could increase by as much as 40 per cent by the end of the century.
It also anticipates that allergy season will begin earlier, with up to 19 extra days of pollen in certain places, exacerbating conditions for allergy sufferers.
Global warming is bringing new allergenic plants to Europe
Previous research has looked at the changing patterns of pollen release in Europe. A study from 2019 found that the pollen season has been extended by an average of 0.9 days per year in Europe.
Research from 2014 found that in urban areas, where most Europeans live, warmer temperatures exacerbated by the urban heat island effect have led to earlier pollen season starts.
Rising temperatures and elevated atmospheric CO2 concentrations stimulate plant growth, intensifying pollen concentrations in the air, other studies have concluded.
Heightened humidity and thunderstorms during the pollen season can also increase pollen and allergen concentrations in the air, which can provoke more severe allergic reactions and asthma attacks.
Global warming is facilitating the migration of new, invasive plant species to Europe, too.
Ragweed, for example, arrived on the continent several decades ago, brought over with seed deliveries from North America.
The plant is highly allergenic and releases pollen late in the year, in September, thus also potentially lengthening allergy season.
Medical professionals have key role in addressing the climate crisis
The effects of climate change on pollen season will increase allergy suffering, even for originally weak allergens.
Under the Intergovernmental Panel on Climate Change’s (IPCC) medium greenhouse gas emissions scenario, ragweed sensitisation is expected to increase by up to 200 per cent in some European countries by 2050, according to a 2017 study published in Environmental Health Perspectives.
People already sensitive to pollen are expected to experience more severe and prolonged allergic symptoms, which can exacerbate respiratory problems and increase mortality for asthma sufferers.
The researchers from George Washington University hope that the pressure on medical professionals to understand the impact of the climate on allergic conditions in order to prepare patients for rising pollen levels can be beneficial for the planet, too.
“Physicians are uniquely positioned to witness the impact of allergic rhinitis on patient outcomes and can adapt their practice as climate change intensifies,” lead author Alisha R. Pershad said.
“As trusted voices in the community, they should leverage their frontline experience to advocate for meaningful change in addressing the climate crisis.”