It’s allergy season and that means sneezing, coughing and itchy eyes for many. If you’ve wondered if your allergies are getting worse, you’re not alone. New research shows that pollen season is getting longer and more intense. But why? Lew Ziska, associate professor at Columbia University and a co-author of a new study on pollen, joins The Excerpt to share the science behind an intensifying allergy season.Let us know what you think of this episode by sending an email to [email protected] Transcript available hereAlso available at art19.com/shows/5-ThingsSee Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.
Chapter 1: What is causing the worsening allergy season?
Hello, and welcome to The Excerpt. I'm Dana Taylor. Today is Thursday, March 10th, 2025, and this is a special episode of The Excerpt. Spring is here and that means that we're sneezing, itchy eyes and noses, and congestion that define allergy season. If you're one of those who suffer from seasonal allergies, you might have noticed that it seems to be getting worse with each year.
Even if you didn't suffer regularly from pollen allergies in the past, you might have noticed that you are now. Turns out pollen allergens are getting worse. The question is why? To help us understand all the forces at play and what we can do to minimize our suffering is Lou Ziska, Associate Professor at the Mailman School of Public Health at Columbia University. Thanks for joining me, Lou.
I'm happy to be here.
Chapter 2: How is climate change affecting pollen levels?
You recently co-authored a study that looks at how climate change is impacting allergy season here in North America. Tell me what you found.
We've been looking at the role of changing winters, that winters are becoming more wild and that they're starting later and spring is starting earlier and falls are being delayed. That increase in the frost-free season is allowing greater exposure of plant-based pollen to people who are allergic to that pollen. So with that change in seasonality, in addition to changes in carbon dioxide,
and other things that make plants grow more, we're seeing a increase in the overall amount of pollen, but also the time in which you're exposed to that pollen. So we think those are two of the underlying reasons why the pollen season is becoming more severe.
It makes sense that with longer periods of warmth, plants have longer flowering seasons, but climate change also affects the range of where plants can grow. How are plants able to move into new environments?
That's a very good point. And yes, they are. One of the things that we use as sort of a model for this is we looked at an urban environment. Urban environments are often called heat sinks because they're warmer than the surrounding area. And so we began by planting ragweed, which is a pollen source that everyone is familiar with.
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Chapter 3: What is the impact of urban environments on pollen production?
But we planted ragweed in a rural area in a farm, and then we put the same ragweed in the same soil along this transect from the farm to downtown Baltimore. And what we found doing so was that the warmer temperatures in Baltimore, the longer growing season in Baltimore,
The increased carbon dioxide in Baltimore allowed for an average ragweed plant to produce 10 times more pollen in that environment than it did out in the rural environment. So it's something that we think is having a direct effect in regards to the amount of pollen that you're being exposed to.
But that rural to urban transect is sort of a harbinger, if you will, of things to come with respect to climate overall. In addition, we also looked at, for the Northern Hemisphere, different pollen sets that we obtained from really dedicated allergists and botanists throughout the world.
And seeing that in recent, the last 20 years or so, that what we were seeing at the city level is also occurring globally, at least for the Northern Hemisphere.
One factor in how bad allergies are is the concentration of allergens. How has the concentration of pollen in the air changed over the years?
We're seeing increasing changes with regard to the sort of three stages of plant-based pollen. In the spring, it's primarily trees. In the summer, it drops off, but it's still there in terms of grasses and weeds. And then in the fall, it picks back up again with respect to ragweed, which is the primary pollen producer at that time.
And what we're seeing is the concentrations are increasing, particularly in the springs and again in the falls, in regard to the amount of pollen. And also we're seeing that if you have storms that occur at that time, particularly lightning storms, what it can do is it can break the pollen apart.
So it's not just one bit of pollen, but it's lots of little bits of pollen that in turn can inflame your lungs and make it even worse. So those are the things that we've observed so far.
I wanted to ask how do longer and more intense pollen seasons impact public health, particularly respiratory health?
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Chapter 4: How has the concentration of pollen changed over the years?
What groups of people are most affected by the changes in pollen season?
Particularly young individuals and elderly are the most affected.
What are some potential solutions or actions that can be taken to mitigate the impact of climate change on pollen seasons?
One of the things that we can do, at least at the local level, is to begin to do a better estimate of when the pollen is coming about so we're prepared. But one of the ways to prepare is to make sure that you can close your windows, make sure the pollen isn't coming in, having HEPA filters within your home to process the air.
Chapter 5: What can we do to minimize allergy symptoms?
Chapter 6: Are there long-term trends in allergy seasons?
What are some potential solutions or actions that can be taken to mitigate the impact of climate change on pollen seasons?
One of the things that we can do, at least at the local level, is to begin to do a better estimate of when the pollen is coming about so we're prepared. But one of the ways to prepare is to make sure that you can close your windows, make sure the pollen isn't coming in, having HEPA filters within your home to process the air.
And for myself, one of the things I do, particularly during high pollen season, is to wash my clothes more frequently because often when I'm outside, I get a lot of pollen on my clothes and then I start breathing it in. So I try to wash my clothes a little more frequently.
And how can individuals with allergies or respiratory conditions manage their symptoms during longer pollen seasons?
When you look at their symptomology and the effects of that, one of the things, of course, is to work with your doctor in terms of the medication that you need to take, whether or not you need to wear a mask to prevent large inhalation of pollen. There are a number of things that pharmacology and modern science and medicine can do to help in that regard.
Lou, what's next for your research here?
Well, yeah, they've cut all funding, so it's hard to know what the next steps are going to be. One of the things we'd like to try and do is to look at the secondary effects of breathing in pollen, particularly in regard to the immune system. One of the things that pollen can do is to stimulate your epithelial cells in terms of your respiratory pathway.
And by doing so, it may actually increase your susceptibility for airborne viruses. There was some work that we were doing looking at how things like COVID and other airborne viruses could be impacted by pollen and the effects that pollen has on your immune system. That's something we think is important. We'd like to know more about it.
That would probably be the next thing on my list of research topics.
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