Climate change will worsen pollen allergies
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* Kayla Yup

![Figure1](http://www.thenationshealth.org/http://www.thenationshealth.org/content/nathealth/53/1/11/F1.medium.gif)

[Figure1](http://www.thenationshealth.org/content/53/1/11/F1)

Headaches are a symptom people with seasonal allergies may experience more of as climate change worsens, a study says.

Photo by FG Trade, courtesy iStockphoto

People who endure sneezing, headaches, runny nose and other conditions during allergy season will suffer even more as climate change worsens, a new study predicts.

Published in October in *Frontiers in Allergy*, the study modeled scenarios based on the likelihood that greenhouse gas emissions would remain high over the next few decades, consistent with current levels. The team examined two prominent types of pollen, ragweed and oak, to determine the future of flowering plants and the seasonal allergies they would be expected to trigger under the model. The outcome does not bode well for allergy sufferers.

“For people who have respiratory problems, from allergic rhinitis to COPD to asthma, it’s not going to be good,” Panos Georgopoulos, PhD, study lead author, told *The Nation’s Health*. “They (will) have more days of potential health effects, so understanding this helps us prepare.”

Rising carbon dioxide levels are essentially “food for plants,” said Georgopoulos, who is a professor of environmental and occupational health and justice at Rutgers University School of Public Health. The increase means many plant species will grow bigger and emit more pollen. Meanwhile, rising temperatures will lead to an earlier bloom for plants and a longer pollen season for plants such as ragweed.

Seasonal allergies can span spring, summer and fall, depending on location. Oak trees flower in the spring and are among the most allergenic tree species in the U.S. Ragweed, which has a wide distribution and causes hay fever, dominates during late summer and fall.

The study models found that by mid-century, every region in the contiguous U.S. will see ragweed pollen season begin earlier and last longer, with pollen concentrations increasing in most regions. Changes to oak pollen vary by region, hitting the Northeast with the most significant surge in pollen concentration.

Even places that currently don’t have oak and ragweed pollen will be impacted. Both Nevada and northern Texas, which now lack oak coverage, are predicted to experience an increase in airborne oak pollen ranging from 20% to 100% by 2047. Mean oak pollen concentrations could jump over 40% in the Northeast and Southwest regions, where levels were relatively low at the start of the century.

![Figure2](http://www.thenationshealth.org/http://www.thenationshealth.org/content/nathealth/53/1/11/F2.medium.gif)

[Figure2](http://www.thenationshealth.org/content/53/1/11/F2)

Photo by Prudencio Alvarez, courtesy iStockphoto

Massachusetts and Virginia are similarly strangers to ragweed, yet these states could see as much as an 80% increase in airborne ragweed pollen by mid-century. Mean concentrations of ragweed pollen could climb over 20% in the Northeast and Southeast.

“We worry more about the big urban, suburban areas,” Georgopoulos said. “We’ve seen ragweed expanding into Northern areas, and it especially has been flourishing in urban cities where you have more emissions of carbon (from) all the traffic and all the people.”

The urban heat island effect, through which cities tend to be significantly warmer than surrounding areas, could mean an earlier start and longer lifespan for ragweed.

With as many as 60 million people in the U.S. estimated to suffer from pollen-related allergic rhinitis, the climate changes could have a heavy impact. According to the Centers for Disease Control and Prevention, 70% of people with allergies — characterized by sneezing, runny nose, and congestion — also experience allergic conjunctivitis, an inflammation that leads to red, watery or itchy eyes.

“The most logical answer right now in terms of reducing pollen is to have strategies to reduce carbon dioxide emissions,” Georgopoulos said. “(If) we have lower levels of carbon dioxide, if temperatures don’t rise as much, the pollen levels are not going to rise as much.”

For more information on the study, visit [www.frontiersin.org/journals/allergy](https://www.frontiersin.org/journals/allergy). For more on the impacts of climate change on human health, visit [www.apha.org/climate](https://www.apha.org/climate).

*   Copyright The Nation’s Health, American Public Health Association