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Health, Science & Environment

Seasonal Allergies Making You Miserable? Science Says It’s Because Of Climate Change

A woman hiker using an inhaler outside in the woods.
Allergy seasons are longer and more intense than they were 30 years ago, and according to a new study climate change could be driving that.

Itchy eyes. Runny nose. Foggy … everything. The weather is warming and that means it’s time to break out the antihistamines. But does it feel like allergy season starts earlier every year? A new study led by William Anderegg, an ecologist at the University of Utah, shows rising temperatures from climate change can cause pollen seasons to last longer and be more intense than they were just a few decades ago.

This interview has been edited for length and clarity.

Caroline Ballard: What got you interested in the relationship between climate change and allergies?

William Anderegg: I experience and suffer from allergies quite extensively. That's always made me interested in what are the drivers of pollen and what makes certain allergy seasons really bad. Then, as an ecologist and somebody who studies plants, we've known for a long time that plants are very sensitive to temperature. When you turn up the temperature or you turn up the carbon dioxide concentrations in a greenhouse — in a very small controlled environment — they tend to produce a lot more pollen. So some of the personal and the scientific interests together really drove this study of this climate change making pollen seasons worse.

CB: You found that over the last 30 years, pollen seasons are 20 days longer and have about 21% more pollen in the air. What's driving that?

WA: That's right. Across the U.S. and through Canada, pollen seasons are getting longer and they're getting more severe. There's more pollen in the air. We had 60 long-term pollen monitoring stations [in our study] that were mostly co-located with medium to large sized cities. Our study looked at a number of potential drivers, and far and away the biggest driver is temperature — warming springs and warming whole years driven by climate change. We looked at a lot of other factors too — whether this could be related to rainfall or changing urbanization and vegetation in urban areas. And really, temperature was the biggest control of pollen levels and pollen seasons across the country.

CB: I also am an allergy sufferer and recently when I've taken my dog for morning walks, I could really feel it in my eyes, runny nose — classic allergies. And it's only early mid-March. Besides the annoyance and everything that can be irritating about allergies, what are the more serious effects of a longer and more intense allergy season?

WA: Pollen has a number of very serious health effects for many people. We see that pollen is really strongly connected to hospital admissions for asthma and other respiratory exacerbations. So it can really put people in the hospital — and it does. There's also a lot of research with things that you might not necessarily expect. Pollen has impacts on school children both through their asthma and their health, but also it decreases how kids do in school during really bad pollen periods. They're unable to concentrate and they perform less well in school.

There's also a little bit of early research indicating that when our lungs are aggravated due to pollen that we may be more vulnerable to viruses. There's been one study that found during really high pollen periods, people were more vulnerable to the viruses that cause the common cold, which could potentially apply to [COVID-19] as well. We will need more research to know for sure.

CB: What could allergy season look like 15 or 20 years from now?

WA: This overall signal is that allergy seasons have started about 20 days earlier since the 1990s. That's basically getting a week earlier every decade. So we are expecting these seasons to keep getting earlier and to keep getting longer. Some places pollen seasons are year-round. Across parts of the South and Texas and Florida, it's always pollen season — just different species and different things pollinating. That line is going to probably move northward. More places are going to be experiencing year-round pollen seasons and places further north are just going to have lengthened pollen seasons.

CB: What can be done about that?

WA: Obviously, one of the biggest things is that our study showed a really strong link to human-caused climate change. This is a really clear example that climate change is here. It's now. It’s impacting us in every breath we take in the spring. So that I think adds some additional urgency to trying to tackle and head off the worst impacts of climate change as quickly as we can. That will benefit our health.

At a more local and regional scale, there's a whole suite of actions we can take to try to reduce our vulnerability and our exposure to pollen — whether that's maybe keeping kids inside on really bad pollen periods, ramping up allergy medications, giving warnings to clinics and hospitals that we're about to see more asthma attacks. There are a number of adaptations and changes we can make more locally to reduce our vulnerability to pollen seasons.

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