Allergies may be worsening as pollen season gets warmer and longer : Shots - Health News As the climate warms, plants bloom earlier in the spring, overlap with other species and could even start growing in new locations. That's bad news for people with pollen allergies.

Rising temperatures prolong pollen season and could worsen allergies

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Springtime is on the way, which means flowers and, of course, allergies for many people. New research shows that allergy season could get much worse as the climate gets hotter. NPR's Lauren Sommer reports.

LAUREN SOMMER, BYLINE: When people complain about an especially bad allergy season, they're not necessarily wrong. Allison Steiner, a professor of atmospheric sciences at the University of Michigan, says pollen levels can vary quite a bit because plants respond to the environment around them.

ALLISON STEINER: So obviously temperature plays a big role. So as springtime temperatures get warmer, we might expect that flowers will come out earlier on the trees.

SOMMER: Temperatures are getting hotter as humans burn fossil fuels, so Steiner and her colleagues wanted to know how that would affect pollen levels. They ran complex computer models and found it's not good news for allergy sufferers.

STEINER: Trees and grasses and weeds are essentially responding to these kind of changes and putting out more pollen.

SOMMER: By the end of the century, if carbon emissions remain high, Steiner found allergy season could begin as many as 40 days earlier. That's because it gets warmer earlier in the year, the signal for trees and other plants to begin flowering. In the fall, those warmer temperatures could make ragweed and other plants release pollen longer, up to 19 days longer. That means allergy season would be extended at both ends.

STEINER: This is another sort of unintended consequence of climate change that hasn't been explored that much, and that has a big impact on human health.

SOMMER: Climate change is already having an effect on allergies, says William Anderegg, an associate professor of biology at the University of Utah.

WILLIAM ANDEREGG: Pollen seasons since the 1990s have gotten substantially longer and start earlier. And there's more pollen in the air, so pollen seasons have gotten more severe.

SOMMER: Seasonal allergies are more than just a nuisance. It means more visits to emergency rooms, he says.

ANDEREGG: Pollen has major health consequences for a huge number of people. I mean, millions of children struggle with asthma that pollen can affect. And there are a lot of non-intuitive effects - things like worker productivity on the job. It can affect kids' learning in schools and their performance on tests.

SOMMER: And as temperatures keep warming, some plants may move and start growing in new locations. So allergy season won't just shift when it's happening but where it's happening, too.

Lauren Sommer, NPR News.


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