DC’s allergy season has lengthened by 20 days, study shows

The spring allergy season in the nation’s capital has gotten longer and more impactful over time, according to a new study released by Climate Central, a nonprofit group that tracks the effects of climate change.

“It’s making it worse for the millions of Americans who suffer from pollen and mold allergies,” said Lauren Casey, a meteorologist with the group.

The study found that the allergy season nationwide has lengthened by 15 days on average since 1970.

Researchers analyzed temperature trends across more than 200 cities, showing that the season is now 20 days longer in D.C., eight days longer in Baltimore, and 29 days longer in Richmond, Virginia.

When warmer temperatures arrive earlier in the year, plants start to bloom earlier.

That leads to pollen being released into the air, triggering those aggravating symptoms such as sneezing, runny nose and itchy eyes.

While allergies can be a nuisance for some, they can be debilitating for others.

Allergies can interfere with daily activities and make it difficult to sleep or concentrate. They can lead to other health problems, such as sinus infections and asthma attacks.

“The importance of this is awareness for people who deal with allergies,” Casey said. “Typically if you have allergies, you know the time of year when they get triggered; but that whole paradigm is changing.”

Warmer weather earlier in the year led to an early peak bloom prediction for D.C.’s famous cherry blossom trees.

The National Park Service predicted that it would be between March 22 and March 25, about two weeks earlier than normal.

An earlier spring can also lead to changes in the types of allergens to which people are exposed.

For instance, warmer temperatures can cause mold to grow more quickly, which can increase the amount of mold spores in the air.

“Some of these figures are downright astounding,” Casey said. “The allergy season in Reno, Nevada, for example, has increased by 99 days.”

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Nick Iannelli

Nick Iannelli can be heard covering developing and breaking news stories on WTOP.

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