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Climate change fueling increase in pollen, allergies

If even hearing the word “ragweed” makes your eyes water, you might be one of the nearly 45 million Americans with seasonal allergies. Researchers say climate change is fueling the rise in allergies and asthma.

Jenny Fischer has been taking over-the-counter medication for allergies for a long time. Without it, she suffers cold-like symptoms: a runny nose, sneezing and congestion. An allergy pill usually made it better. But a couple of years ago, things started to get worse.

“I’d be out at 5:30 in the morning walking my dog, and it would just be huffing and puffing. And, you know, I couldn’t catch my breath. It's scary," she said.

"The number of patients calling in for appointments for allergies has just skyrocketed."

Her doctor, David Skoner, diagnosed her with asthma. Like many allergists he's seeing more patients with allergies, and those allergies are getting more severe. Skoner spends his lunch hour filling out new prescriptions.

“The number of patients calling in for appointments for allergies has just skyrocketed," said Skoner. The American College of Allergy, Asthma and Immunology says a top reason for that is climate change. Higher temperatures and carbon dioxide levels are affecting plants, and that’s leading to more allergies.


Credit Julie Grant / Michigan Radio
Michigan Radio
Asha Patel, an immunology researcher, uses a Burkard Spore Trap to collect pollen on the roof of Allegheny General Hospital in Pittsburgh.

Determining the allergen density

Immunologist Asha Patel walks up to the roof of Allegheny General Hospital in Pittsburgh every morning to take pollen counts. She uses a machine called a Bukard Spore Trap. It looks kind of like a small weather vane. And Patel says it pulls in air like a large nose.

“There’s a suction created. So it draws the air through this opening right here, and the sample is collected inside," she says. The machine is used to take daily pollen counts and Patel distributes this information to allergists, their patients and weather channels. 

Patel takes a glass microscope slide out of the spore trap. It’s the one she put in yesterday and it’s covered with speckles. She takes it down to the lab and dots on pink dye. Under the microscope, she watches as a perfect circle emerges. She says it’s the pollen from a common weed.

Ragweed season lasting longer

Researchers do this kind of pollen collection all over the country, and they've seen trends emerge.

Dr. Leonard Bielory of Rutgers University has been studying the connection between pollen levels and the throngs showing up at his office.

“I saw a hidden signal in the pollen count changing over time. And I started correlating that we’re seeing patients earlier and more patients — the volume seems to be increasing. And some who were moderate or mild in years past are now more severe," he said.

In a study published by the National Academy of Sciences, Bielory and other researchers looked at a common allergen, ragweed, in the Midwest and Canada. They found the ragweed season in Canada was almost a month longer in 2009 compared to 1995. Bielory says the ragweed season in our region is about five days longer than it was twenty years ago.

Plants producing more allergenic proteins

Researchers looking at the impacts of climate change also find that as carbon dioxide levels rise, the pollen is becoming more severe. Lewis Ziska is a researcher with the U.S. Department of Agriculture.

“Just changing the CO2 from the early part of the 20th century to the latter part of the 20th century, for example, doubles the production of pollen from a single plant. And there was some indication that it was also more allergenic pollen. That is, it was producing more of the proteins that people were allergic to," Ziska said.

Bielory says the worsening pollen is especially dangerous for children who already have respiratory problems.

“And you will cause an inflammatory mix, or what I call the 'witches brew', where we have the temperature, ozone and pollen all mixed together, you will cause an incredible inflammatory response of the eyes, nose, and therefore in those who are more prone to it, the lungs as well, leading to more asthma,” he said.

On high pollen days, Bielory suggests that people with respiratory problems take over-the-counter medicine preventatively, so that itchy eyes and runny noses don’t turn into dangerous asthma.


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