Why Climate Change Is Bad News for People With Seasonal Allergies

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Mother Nature’s calendar is being disrupted by climate change, and that’s wreaking havoc for the 25 million Americans people with seasonal allergies, also called seasonal allergic rhinitis or hay fever, according to a new study from the University of Maryland.

The authors of the study, published in PLOS One, analyzed NASA satellite data to identify the start of spring throughout the U.S., and Centers Disease Control and Prevention (CDC) survey information on more than 300,000 people with seasonal allergies. They found that the itchy, watery eyes; runny nose, congestion, cough, and other symptoms of hay fever were worse when the timing of the spring “green-up” changes, and that hay fever prevalence is about 14 percent higher than normal when the onset of spring occurs earlier or later than usual in an area.

This is because plant growth is largely determined by temperature and can be affected by even minor variations. When spring arrives earlier than normal, trees bloom sooner, creating a longer pollen season – and tree pollen is a major source of seasonal allergies. When spring arrives later than normal, many types of trees and other plants may bloom at once, creating a high concentration of pollen.