By Natasha Nellis

Researchers say warmer weather will cause pollen-producing plants to bloom earlier and last longer, creating longer allergy seasons. Photo by: Natasha Nellis

Spring is the time of hope, blossoming trees and soft spring breezes that carry just a hint of winter chill. Unfortunately, also the time of year when those same blooms release the pollen that hails the time of sniffles, sneezes, and allergy misery.

And, thanks to climate change, the allergy season is going to get much worse: a warming planet means longer growing seasons. That means more of that pesky allergy-producing pollen.

New research published in Nature shows pollen emissions could increase 40% by the end of the century, with an additional 59 days more of sniffling and sneezing.

Seasonal conditions vary from country to country. In North America, allergy season used to start around St. Patrick’s Day, but historical research shows that on average the season now starts 20 days earlier and lasts eight days longer. About 20% more pollen is also released into the air compared to 30 years ago.

In a tweet, the study’s lead author Allison Steiner says, “Because up to 30% of the population is affected by seasonal allergies, climate could further impact daily symptoms for many, plus higher pollen loads could lead to greater sensitization of other individuals.”

In the United Kingdom, the University of Worchester’s pollen calendar, which is produced in partnership with the Met Office, looks at when, and what type of plants, produce pollen. On average, allergy season begins in early spring and ends in late summer in the UK.

While the increased heat is driving droughts in forests and grasslands, some of the biggest pollen-producing plants thrive off warmer temperatures and higher levels of carbon dioxide. This means they are growing bigger and producing more leaves.

Steiner and co-author Yingxiao Zhang built models based on historical data that predict pollen emissions based on factors such as precipitation, temperatures, and carbon dioxide. It also factors in changes in plant types in a region over time. As trees and grasses expand their footprint, other plants like ragweed would disappear. Ragweed is the biggest allergen producer in the northeast. It’s predicted to decrease by 80% if emissions continue at their current trajectory.

“This study provides an important predictive tool to start to investigate the consequences of climate change on future plant communities and their corresponding health effects,” write Steiner and Zhang.

The model analyzed two scenarios: a middle of the road greenhouse gas (GHG) emission future, at an increase of 2 to 3 degrees Celsius, and a more extreme one, an increase of 4 to 6 degrees Celsius. In the more extreme case, carbon dioxide levels would more than double, resulting in a longer and more intense pollen season.

The middle of the road scenario highlights the importance of curbing GHG emissions. The impacts of pollen decreased by half when compared to the high emissions scenario.

“The most recent estimates suggest that between 10% and 30% of the global population is impacted by seasonal allergic rhinitis,” says Hannah Jaffee, research analyst at Asthma and Allergy Foundation of America.

And that number is expected to increase, she says.

“Unfortunately, these trends show no sign of slowing down, and a lot of it can be explained by increased carbon emissions that contribute to the longer pollen seasons,” says Jaffee.

The World Health Organization predicts half the world’s population will develop at least one allergic disorder by mid-century.

In the U.S., medical costs associated with allergies and asthma exceed $3 billion every year, says Jaffee. About half of that linked to prescription medicine costs.

“Research has also shown that pollen exposure, and the earlier onset of pollen exposure in the year, is associated with increased hospital admissions for asthma attacks,” she says. “But pollen doesn’t just impact allergies.”

The AAFA says nearly 60% of people with asthma have “allergic asthma”. This means their asthma is triggered by allergens such as pollen.

“Nearly 60% of people with asthma have allergic asthma.”

Asthma and Allergy Foundation of America

Studies also show students with allergies perform worse than their peers in school; while adult’s productivity at work decreases when allergies kick in. Researchers also found an uptick in emergency room visits on days when pollen concentrations are high; this comes with the associated costs to people and healthcare systems.

However, solutions may be closer than we think. Several companies are developing AI technology that automates the counting of daily pollen emissions. Additionally, weekly projections of pollen counts – similar to air quality forecasts, could become the norm.

“Pollen forecasts can help individuals prepare, but allergy symptoms may still be present even if the forecast predicts low or moderate amounts of pollen,” contends Jaffee. “Having a comprehensive system that would provide location specific counts in real-time would allow for more meaningful management, but it’s also important to note that more systematic solutions targeting the reduction of carbon emissions are needed to curb the impact of pollen on people with asthma and allergies.”

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