Fall Allergies Worse Than Usual? Climate Change Is The Culprit ... - Block Club Chicago

Fall Allergies Worse Than Usual? Climate Change Is The Culprit, Experts Say

CHICAGO — There is a hidden consequence lurking behind the unusually warm falls in recent years. The delayed frost brought on by climate change has resulted in an allergy season far longer and more intense in Chicago than a few decades ago, according to experts.

Fall allergies are typically caused by two main culprits: ragweed pollen and mold spores. The extended warm season has created the perfect growing conditions for the molds and ragweeds that are to blame for the itchy eyes, sneezing and congestion that torments many Chicagoans in the fall.

The effect is an allergy season that may be double the length of previous years for some Chicagoans, depending on their allergy sensitivities, a local expert said.

The increase in fall allergens is tied to multiple factors related to climate change, said Allison Steiner, professor of climate and space sciences at the University of Michigan and co-author of several studies on the effects of warming on airborne pollens.

Rising temperatures spur plants to grow, alter a plant’s pollen emission patterns and push back the first frost dates that usually kill ragweed, Steiner said. The higher level of carbon dioxide in the atmosphere also allows ragweed to grow faster, she said. That means there are more ragweeds around in the fall, and they are larger plants that produce more pollen.

“Temperature is a dominant factor for when plants are flowering. But precipitation can also influence allergens as well. It can trigger the formation of mold,” Steiner said. “So as the temperature and precipitation patterns are changing, we’re going to start to see changes in allergens, as well.”

Historically, ragweed pollen disappears by mid to late September, said Dr. Christina Ciacco, chief of pediatric immunology at UChicago Medicine. But this year, scientists detected ragweed pollen in the air until mid-October, she said.

Due to the longer tail end of the growing season, immunologists are detecting ragweed pollen about two weeks longer than usual. A 2011 study by the Department of Agriculture’s Global Change Laboratory found the ragweed allergy season has extended by up to 27 days since 1995.

“The pollen likes the increased carbon dioxide,” Ciaccio said. “The allergy seasons are longer, and the peaks are higher. We’ve been seeing pollen a couple weeks longer than we would expect.”

The ragweed pollen season has ended in Chicago. Meanwhile, outdoor molds release spores that contribute to allergic reactions from late summer through fall, adding to the discomfort experienced by many during this season.

Those who suffer from allergies will likely struggle with mold spores until the weather gets much colder, Ciaccio said.

Alterneria mold thrives in the fall due to the fallen leaves that decompose on the ground, Ciaccio said.

Last year, this type of mold caused allergies for some Chicagoans “all the way into January,” Ciaccio said.

“It has a beautiful, fresh smell to it. If you smell a sweetness in the air — that’s just mold, and people are very allergic to it. It decays the leaves that fall from the trees. If you go to a pumpkin patch, it’s the fungus that eats the vines on the pumpkin patch,” Ciaccio said.

Molds continue to release spores until a hard frost, where the weather dips several degrees below freezing for a significant amount of time, said Dr. Mahboobeh Mahdavinia, chief of allergy and immunology at Rush University.

Twenty years ago, physicians typically expected the cold to kill off the outdoor molds around Thanksgiving. But the allergy season may now be nearly doubled for some Chicagoans, depending on their allergy sensitivities, Mahdavinia said.

“You need a hard frost for the outdoor molds to go down to undetectable levels. But the hard frost is happening much later, even into mid-January,” Mahdavinia said.

Immunologists are also finding that the types of allergens present in the air are changing. The warmer climate has allowed molds that previously couldn’t survive outside the Southern states to become common in Chicago, Mahdavinia said. Scientists and physicians have to change their testing panels for allergens to take into account a wider range of spores and pollen.

The warmer climate impacts “the transfers of the allergens, so we’re seeing allergens more and more in places where we shouldn’t see them,” Mahdavinia said.

The “longer and higher exposure” to mold spores and pollens is causing children to develop allergy symptoms “more rapidly” and at younger ages, said Dr. Sai Nimmagadda, an immunologist at Lurie Children’s Hospital and chief allergist at the Center for Food Allergy & Asthma Research.

“I’m seeing 2- and 3-year-olds starting to develop congestion and seasonal allergy symptoms, which to me is a bit surprising,” Nimmagadda said. “With the higher concentrations of pollens and the longer seasons, we’re starting to see kids develop allergies younger and younger.”

Fall allergies are a nuisance, but they can also have serious health impacts, especially among children and people who lack access to medical care. Allergies can worsen respiratory health conditions and can cause problems like asthma attacks, Nimmagadda said. It is important for those with allergies to see an allergist who can do tests to determine what a person is allergic to and offer treatments, he said.

As the allergy season extends through late fall and into the winter, there is more overlap with cold and flu season. This makes people who suffer from allergies even more likely to get sick with unrelated illnesses due to the inflammation caused by spores and pollen.

“Uncontrolled allergies make people prone to viral illnesses. An allergic nose is more prone to infection. It’s inflamed, the pathways are not that clear. Someone with allergies is at significantly higher risk,” Mahdavinia said. “The longer they suffer from the allergy season, the number of infections they have will be bigger.”

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