Short Wave - Itchy? Air Pollution May Be Making It Worse

Episode Date: July 8, 2025

Short Wave producer Hannah Chinn has adult-onset eczema. They're not the only one. Up to ten percent of people in the United States have it, according to the National Eczema Association — and its prevalence is increasing. Despite its ubiquity, a lot about this skin condition remains a mystery. So today, Hannah's getting answers. In this encore episode, they sat down with Raj Fadadu, a dermatologist at the University of California, San Diego, to ask: What is eczema? What triggers it in the first place? And might climate change make it worse sometimes?If you liked this episode, check out our episode on the science of itchiness. Also, follow us! That way you never miss another episode.Interested in hearing more about climate change and human health? Email us at [e-mail] — we'd love to hear your feedback!Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, shortwavers, it's Hannah Chin. I'm a producer, which means you usually hear my name in the credits. But today, today I'm behind the mic. Because for the majority of my adult life, I've had eczema. Up to 10% of adults in the U.S. do. So if you're one of them, you know exactly what I'm talking about. And if you don't, eczema is a condition that makes patches of your skin rough,

dry, and overwhelmingly itchy, sometimes to the point of losing sleep. It's not contagious, but its prevalence has been increasing over the past few decades. And I'm not the only person I know who has it. My mom has had it for way longer. It probably started before I was five, before kindergarten. It was a rash that was weepy and it would sting if it got wet. And so, like, at night, my parents would put some kind of cream on it. and I would have to sleep with my arms above my head.

As she got older, she tried all kinds of things, creams, lotions, topical steroids. You can actually see it in a lot of our family pictures. It's this red, angry rash on her face and arms that just wouldn't go away. And around the time that I was 12 or 13, she had a tipping point. It was all over my face and I looked like lobster woman. And basically I was realizing it was getting worse and worse despite, any medical intervention. Until one night, she spent away from our house, and then kind of like magic, the eczema

started going away. And I was like, oh my goodness, I'm not itchy and I feel good. And it was noticeable. Like, oh, my goodness, this is a environmental thing. This is not just me. And that's why I came home. I'm like, let's change the environment. And I remember this because a bunch of things in our house changed.

My mom put protective covers on the bed. She took down every curtain in the house. We pulled out all of the carpet, this like shag carpet that was wall to wall in the basement. That environmental shift really helped my mom. Her exoma is manageable now. And maybe it's just because of our genetics. But my eczema too is really dependent on the environment that I'm in. When it's hot outside or dusty inside, when there's a lot of pollen or smoke or smoke

or other pollution in the air, my skin starts freaking out. I feel like as climate change has progressed throughout my youth and adulthood, I'm seeing how a lot of the damage is done to the environment are harming human health. And one of the ways that's happening is through the generation of air pollution. But there hasn't really been a lot of study on air pollution and skin disease. Raj Vedadu is a resident physician in dermatology at UC San Diego. And just a few years ago, he started filling this gap in the research by doing a study on the correlation between short-term air pollution, specifically wildfire smoke, and a topic dermatitis, or eczema. And we found that this short-term exposure to air pollution did have really quick impacts on the prevalence of both eczema and itch.

It was a little shocking and disturbing to find this result because, you know, I was maybe hoping that just people who had a short amount of air pollution. exposure wouldn't be too significantly impacted, but instead we did find that even this kind of short-term exposure did impact skin disease. So today on the show, the science of eczema, what it is, how it develops, and how a changing climate could impact our skin. I'm Hannah Chin, and you're listening to Shortwave, the science podcast from NPR. Okay, Raj, what exactly is eczema caused by in the first place? Like, how come some people have it and not others? So people may have genetic risk factors for developing eczema.

For example, mutations in genes related to proteins that affect the skin barrier and the functioning of the skin that make them prone to developing eczema. And then in addition to those genetic risk factors, they may have certain environmental exposures prenatally or early on in life that also make them at increased risk for developing eczema. For example, eczema is part of the atopic triad. So it's atopic dermatitis, asthma, and allergic rhinitis or seasonal allergies. We often see these conditions running hand in hand. Wait, wait. So just to clarify, you're saying people with asthma or seasonal allergies are more likely to have eczema and vice versa? Yeah, so all three of those conditions can run

run together. And so we do commonly see in pediatric patients that they often can develop all three conditions over time. So not everyone will develop all three of them. And that's where it's a little difficult to predict. And there's this complex interplay between genes and the environment that can prevent that from happening or increase the risk for that happening. Got it. Okay, okay, okay. So I want to go back to the study that you did on the correlation between wildfire smoke and eczema. Can you tell me a little bit more about how that works? Yeah, there are many biological mechanisms through which exposure to air pollution ultimately harms skin health. And I would say most of them are related to or end in inflammation within the skin. And that disrupts skin barrier functioning.

And this is what results in itching and rash, which is what we're seeing in eczema. And so the primary ways that air pollution is affecting the skin occurs from the direct. And the direct, interaction of airploons from the outside environment onto the skin. However, it may also be possible that inhaled airploons that enter the lungs can then enter the bloodstream and generate inflammation from within that then find its way into the skin and can cause eczema. Oh, okay, so some of it is coming from outside, but you're saying some of it is potentially linked to inside, like the smoke can affect me from the inside out? Correct, yeah. So, So based on my review of the literature, the main mechanisms are related to air pollution directly

affecting the skin, like particles landing on the skin and causing inflammation. But we are learning more about how air pollution that's breathed into the lungs and then goes into the blood vessels. It can affect the heart. It can affect the brain. And so my thinking is that if it's causing inflammation by entering the lungs, then that kind of inflammation throughout the body can also find its way into the skin. from inside. I'm going to be honest, this is kind of a dark picture you're painting here because you say

like air pollution. You're not just saying wildfire smoke. Like do other environmental pollutants? Like, will those have similar impacts? Yeah, that's a good question. And I'm sort of sure more negative news with you, but it's air pollution really from any kind of source I think is a trigger for eczema, possibly depending on the kind of person. I will say air pollution, is a really complex mixture of different kinds of particles and gases. And so depending on, for example, what material is being burned, what temperature things are being burned at that's generating air pollution, that will ultimately affect what's actually in the composition of air pollution.

And so if you have some really, really harmful synthetic organic compounds that are being generated when you burn buildings from a wildfire versus building trees from. a wildfire, that may then affect human health in a different way, just because the percentage of more toxic chemicals is different from different sources. Okay, I feel like we're mostly focusing on air pollution's effects on people who already have pre-existing skin conditions, like eczema. But what's the deal for people who don't already have skin conditions who might be listening to this podcast?

Like, how does air pollution affect them? Mm-hmm. When it comes to the broader literature on general outdoor air pollution exposure and atopic dermatitis, it's very possible that air pollution exposure can be related to the development of eczema or atopid dermatitis and people who did not previously already have the condition. So I can't tell you that it's a definitive cause of eczema, but I would say it's very fair to say that air pollution can definitely be an environmental trigger, among others, that can cause people to develop eczema or atopic dermatitis later on.

Well, that's definitely not great to hear. I would not wish this condition on other people. All right, so let's get back to this study that you published in 2021. Since then, there's been more studies on wildfire smoke and eczema. And I feel like all of these studies basically say the same thing, which is like, yeah, air pollution is bad for your skin. I guess I'm wondering, where do you see your research fitting into kind of this larger landscape of environmental pollutants and their effects on the human body? Yeah, that's a really good question. I think overall this field of climate change, air pollution, and human health is evolving very rapidly. But now we're really expanding and broadening our focus to take a look at a lot of other human conditions and diseases.

So our research on air pollution, wildfires, and skin disease is really just one piece of the overall picture and puzzle. And we have now additional pieces started being added to this puzzle. Like, for example, taking a look at how air pollution affects cardiovascular disease, neurologic disease, endocrinology, and endocrinopathies. And so I think public health practitioners and medical professionals can really bring. bring this information about health harms into a political realm to help advocate for stronger policies that are going to mitigate climate change and some of the drivers, like the production and use of fossil fuels. Yeah.

Actually, you took us right into my next question, which is, I guess, is there anything that I can do in the meantime to prevent, like, the harm that air pollution will have to my skin. Yeah, definitely for sure. So I always tell people that there are two key aspects. One is prevention and then the other one is treatment. So for prevention of air pollution exposure and reducing the risk of eczema flares, I'd recommend wearing long articles of clothing like long sleeve shirts, long pants to prevent air pollution from directly interfacing with the skin. And sometimes people also forget about indoor air quality. And so make sure you think about things like using an air pure fire. Got it. Okay. And then for the second aspect, which is treatment, I will say unfortunately,

there are no evidence-based guidelines that exist right now. In general, eczema is managed with topical products, including steroidal and non-steroidal medications, but some patients do require stronger medications, such as oral or injectable medications. So overall, I would just say it's very important for people who are experiencing an eczema flare related to air pollution, should really reach out to a medical professional to determine what Truman is going to be most appropriate for them, especially related to the severity of their symptoms. Right, because like you said earlier, like everyone is different and the triggers for eczema for one person may be totally different than the triggers for another person. Correct. Exactly. Thank you so much. I really appreciate

your time and I appreciate you explaining all of this to me. Yeah, of course. Thank you. If you like this episode, make sure to follow us. That way, you can keep track of all future shortwave updates. Also, make sure to check out our episode on The Science of Itchiness. We'll link to it in our show notes. This episode was produced by Rachel Carlson and edited by showrunner Rebecca Ramirez. Rachel, Rebecca, and I check the facts. The audio engineer was Kwayze Lee. Beth Donovan is our senior director and Colin Campbell is the senior vice president of podcasting strategy. I'm Hannah. Chin. Thanks for listening to Shortwave, the science podcast from NPR.