It’s no coincidence: the allergy season is out of control this year


If you feel like your seasonal allergies are worse this year, you’re not alone. Higher temperatures are linked to longer pollen seasons of trees and grasses.

According to a recent study published in the journal Scientific reports, temperature increases in northern California worsen pollen allergies, while changes in precipitation are associated with more mold spores in the air.

“Climate change is really a health issue, and we are living and breathing the effects of climate change now,” said lead author of the study, Kari Nadeau, professor of medicine and pediatrics at the Stanford School of Medicine.

Nadeau, according to to a press release, became interested in the subject because she noticed that patients said their seasonal allergies were getting worse.

“As an allergist, it is my job to follow the pollen counts, and I noticed that the tree pollen season start date was earlier each year,” Nadeau said. “My patients were complaining, and I was like, ‘This is such a tough year,’ but then I was like, wait, I say it every year.”

In the study, researchers collected data at a pollen counting station certified by the National Allergy Bureau in Los Altos Hills, California. They recorded tree, grass, weed, and mold pollens in the air every week over an 18-year period, from 2002 to 2019. In their analysis, the researchers found that the pollen season in northern California now begins earlier and ends later. Specifically, pollen and mold spores from local trees increased by 0.47 and 0.51 weeks per year, in each year of the study. Researchers have also found links between allergen levels and environmental changes.

While the study is local to northern California, the trend continues across the United States.

Beyond environmental changes, it is believed that higher levels of carbon dioxide in the atmosphere are also linked to higher levels of pollen. A separate study published in 2000 found that ragweed plants, a culprit of seasonal hay fever, grew larger when exposed to more carbon dioxide. According to the Union of concerned scientists, carbon dioxide increases the growth rate of plants. This is a particularly frightening prospect in the case of weeds like ragweed.

“In the fall, ragweed is one of the main culprits of allergies, because when it gets hotter it stretches out,” Kenneth Mendez, president and CEO of Asthma and Allergy, told Salon previously. Foundation of America. “Frost is the first thing that kills ragweed, the first frost, so the longer the growing season, the worse the allergies.”

In 2018, a published study in the journal PLOS ONE by researchers at the University of Washington and the University of Massachusetts at Amherst, found that ragweed would expand its reach as temperatures rise. Using machine learning, the researchers calculated that in about 35 years, its ecological range will shift north, bringing hay fever to areas it has never been before. Seasonal allergies can be a trigger for asthma.

Last year, masks coincidentally brought some relief to those with allergies. The size of the pollen grains ranges from 200 microns to 10 microns, and masks could block some of them when people went out.

As vaccination rates rise, Americans collectively look forward to spending this summer outdoors and unmasked, unlike last year’s dismal pandemic summer that many spent locked indoors. Yet, for more and more people with allergies, seasonal allergies are putting a damper on the joy we associate with summer weather.

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