Detroit's allergy season has increased by a month

Allergy season in Detroit increased an average of 29 days between 1970 and 2021, per an analysis from nonprofit climate news outlet Climate Central.

• That's based on the number of days between the last freeze each spring and the first freeze each fall — essentially, the annual window during which seasonal allergy sufferers are most likely to rely on their antihistamine of choice.

The big picture: We're suffering from stuffy noses for longer than most — allergy season increased 15 days on average between 1970 and 2021 across about 200 U.S. cities.

Why it matters: The lengthening allergy season is tied to climate change, with big health ramifications for the roughly one-quarter of Americans who suffer from seasonal allergies — and for respiratory health more broadly.

• "Earlier spring and longer periods of freeze-free days mean that plants have more time to flower and release allergy-inducing pollen," per Climate Central.

The big picture: From 1990 to 2018, pollen counts increased 21% nationwide with the greatest increases in the Midwest and Texas, according to a 2021 study, Axios' Arielle Dreher reports.

• With climate change worsening allergy season, "more people will begin to show allergy symptoms when they never had them in the past," Kathleen Slonager, executive director of the Asthma and Allergy Foundation of America, Michigan chapter, told the Free Press.

What's next: Ongoing climate change means further deviation from what was once considered the norm.