Seasonal allergies: How to reduce symptoms
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ProblemSolved, USA TODAY
If you’ve been sniffling and sneezing a bit more this allergy season than before, scientists might have an explanation for why.
It’s that time of year when ragweed pollen is most likely in the air, according to Dr. Robert Hartzler, emeritus professor of agronomy and extension weed science at Iowa State University. He said when the days get shorter heading into the winter, ragweed is most likely to flower, releasing the common weed’s often allergy-inducing pollen into the atmosphere.
Hartzler said studies have shown pollen produced by ragweed has increased in amount and potency over the past 40 to 50 years. Scientists are starting to see that climate change is likely to blame, he said.
More pollen, more problems
Dr. Lewis Ziska, associate professor of environmental health sciences at the Columbia University Irving Medical Center, said climate change impacts the rate at which common allergens such as ragweed grow.
Ziska said carbon dioxide, which is being released into the atmosphere at high rates due to fossil fuel emissions, is a resource that plants need in order to grow. But higher rates of carbon dioxide in the atmosphere can have abnormal effects on certain types of plant growth, he said.
“As CO2 increases, it can stimulate the growth of plants, and one of the plants whose growth is stimulated is ragweed, and also other plants that produce pollen,” he said.
Ziska said studies are beginning to show that carbon dioxide not only increases the amount of pollen in the atmosphere, but also intensifies its allergen content.
“The protein on the surface of the pollen is changing in such a way that the amount of allergen, that is, the protein that causes the immune response, is also increasing,” he said.
More: Is the heat wave making your allergies worse? Experts say maybe. Here’s what to know
His research, conducted alongside researchers at the University of Utah School of Biological Sciences, found that “human-caused climate change” is linked to a “substantial intensification of pollen seasons in North America over the 1990 to 2018 period.” Their research concluded that pollen seasons start 20 days earlier, last 10 days longer, and on average release 21% more pollen into the air than in 1990.
The study builds off of previous smaller experiments that found strong links between temperature and pollen counts. It draws data from more than 60 pollen count stations across the country. None of the stations are in Iowa, but data gathered originates from nearby Omaha; La Crosse, Wisconsin; and Kansas City, Missouri.
Through applying statistical methods to a series of climate models, Ziska and his colleagues were able to conclude that climate change alone accounted “for around half of the pollen season lengthening and around 8% of the pollen amount increasing.”
More: Hay fever setting in? Here are the 20 worst cities for people with seasonal allergies.
Pollen levels vary by location
While the study relies on compiled data from across the United States, Hartzler warns that everyday pollen levels vary widely depending on one’s location.
The State Hygienic Lab at the University of Iowa used to track regular pollen levels but stopped in 2013 due to state budget cuts. Hartzler said the job was difficult because measuring pollen in one location did not necessarily help in predicting levels in another location.
“If they were measuring locations in Grimes, the amount of pollen there would not really be correlated at all with what’s in Ankeny or Newton,” he said. “It’s primarily how much ragweed is in the immediate neighborhood that determines whether you have a high pollen count or not.”
Therefore acts as small as people not tending to their lawns or building more or fewer fences around a field can all contribute to the population of ragweed plant and consequently the amount of ragweed pollen in the air, he said.
Hartzler said allergy season is likely to last until mid-September. While he admits “there really is no escaping the pollen,” he recommends people with more sensitive allergies stay inside in the mornings when concentrations of pollen tend to be highest.
Francesca Block is a breaking news reporter at the Des Moines Register. Reach her at FBlock@registermedia.com or on Twitter at @francescablock3.
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