Urbanization, Lifestyle, and Skin Barrier Damage in Atopic Dermatitis

Dr Peter Lio discusses how urbanization, modern lifestyles, and shifting environmental exposures may be driving rising rates of allergic rhinitis, food allergy, and atopic dermatitis—and which exposures should most concern clinicians.

Peter Lio, MD is a Clinical Assistant Professor of Dermatology & Pediatrics at Northwestern University Feinberg School of Medicine.

Key Clinical Takeaway

• Modern Lifestyle and the Rise of Atopy:
  • The accelerated increase in atopic dermatitis (AD), food allergy, and allergic rhinitis outpaces any plausible genetic explanation, pointing to environmental and lifestyle contributors.
  • Observational data show that individuals from indigenous or rural populations often develop atopic diseases only after urban migration, reinforcing the influence of urban exposures.
  • Concerning exposures include:
    • Air pollution (e.g., proximity to highways)
    • Indoor environmental toxins
    • Detergent residues, emulsifiers, and other synthetic chemicals
    • Microbiome disruption from lack of natural outdoor exposure
    • Reduced sun exposure and altered circadian rhythm
    • Hygiene-related factors (e.g., reduced parasitic exposure)
• Early Intervention and Skin Barrier Protection:
  • The skin barrier plays a pivotal role in the atopic march and immune sensitization.
  • Recent evidence (e.g., Simpson et al.) shows that early use of moisturizers in infants may delay or prevent the onset of atopic dermatitis, representing a potentially cost-effective and scalable preventive strategy.
  • Aggressive treatment of established AD in infants and young children may modify disease trajectory and reduce risk of developing asthma or food allergy—though long-term data are still emerging.
• Transcutaneous Sensitization and Systemic Allergy Development:
  • Environmental damage to the epidermis increases the risk of transcutaneous sensitization, enabling allergens to penetrate skin and promote IgE-mediated responses.
  • This mechanism explains why skin barrier breakdown can precede and facilitate the development of food allergies and respiratory atopy, challenging the idea that food triggers are primary drivers of eczema.
• Clinical Counseling and Preventive Framing:
  • Dermatologists should proactively educate families—especially of high-risk infants—about environmental contributors to barrier disruption and the benefits of early skin care routines.
  • Reframing allergic diseases as preventable or modifiable through environmental avoidance and barrier preservation empowers patients and may reduce over-reliance on elimination diets or unproven interventions.

This evolving paradigm emphasizes the need for early, preventive dermatologic strategies centered on barrier preservation—particularly in pediatric care—to interrupt the progression of Type 2 inflammation and the atopic march.

Transcript

Dr Lio: Hi, I am Peter Lio. I'm a clinical assistant professor of dermatology and pediatrics at Northwestern University Feinberg School of Medicine in Chicago, Illinois. I'm also the founding director of the Chicago Integrative Eczema Center.

Rates of allergic rhinitis, food allergy and AD continue to climb. How much of this rise do you attribute to modern lifestyles and urbanization, and which exposures concerns you the most?

Dr Lio: So it's a very important question because it does bring this idea up. We hear the same thing about climate change, right? There's sort of a debate about climate change, and I think there is, but this is exactly the right way to ask it. I don't think that anyone, I think that the majority of scientists who study climate change, and I'm not a climate scientist, so I don't really have a strong opinion on it, I'm just sort of looking at what they're saying. It really seems that everyone pretty much agrees there is some effect from modern human activities and all of the waste products we're making and the CO2 emissions, the degree of which is probably reasonable to argue because it is complicated. So I think that may be the truth of if there is a debate, it's how much can we control it? How much damage have we caused and how much are we directly responsible for?

I don't know if anyone can give a perfect answer. And I would say the same thing goes here. How much is modern lifestyle driving these things? And I don't know if we know, but we can certainly look at the progression. Again, understanding that to some degree the genetics of people move way more slowly. The timeline of genetic change is not this fast, and we can see the allergic change is at a totally different scale. So I have to think that we can attribute it to modern lifestyle, urban lifestyle. And in fact, I've heard people talk about this bizarre divide where if they're taking care of, for example, indigenous populations who are living much closer to the earth, when those people, when they come to the dermatology clinic, it's almost never allergic diseases. It might be fungal disease, it might be other types of infection, it might be issues that are different, but no atopy when those even literally the same families were to move into a city and become more urbanized.

Now you kind of earn the modern lifestyle. We often will see some of those people developing allergic diseases. So I think it's pretty compelling that modern life. And the part of the problem is, I dunno which part of it is fully responsible or if it's a combination of things, but it really does seem to be a major driver towards allergic disease. It could be that we're clean and we don't have exposure to parasites. It could be things we're breathing in these indoor environments. It could be to some degree, a lack of exposure to sunlight in the forest. It could be the microbiome shifts when you live internally. It could be all the things that we put on our body and in our body, the emulsifiers in our foods, the detergent residue on our clothing, and of course the air we breathe. There's some very compelling epidemiologic data the closer you live to a highway. So if you're near a highway, much higher rates of atopic dermatitis and other allergies, as you go further away, it decreases. So again, it tells us probably emissions are playing some role in this. I don't know if we can ever get it down to perfectly know how much they're doing because each person's a little bit different too. But boy, I'm convinced I don't need any more convincing It's way past my point. Then it really brings us to the thing of what can we do about it?

You've highlighted the central role of the skin barrier in atopy. What should clinicians keep in mind when assessing environmental contributors to barrier dysfunction across different age groups?

Dr Lio: I think the biggest thing is for our younger patients, and this is becoming much more of the focus now, can we actually intervene early enough to ideally prevent atopic dermatitis and prevent potentially the atopic march that it'd be incredible. There'd be so much savings. We would literally prevent diseases from happening and prevent a lifetime of suffering, a lifetime of expense, a lifetime of doctor's visits, right? And to me, that's the most altruistic. Anybody who says, oh, doctors are all evil. They're just in it for themselves. They just want more and more visits. I mean, literally, we're trying to make ourselves obsolete. That's my goal. If I could prevent it, that would be the best of all, in part because we're overwhelmed. We can't, I can't help everybody. I try and there's so many difficult cases, I would love to prevent them. So that would be the goal.

And I really believe that there's potential here. And we're even seeing with early intervention around the barrier. A beautiful paper came out just in the last year. The senior author is Dr Eric Simpson from OHSU, the Oregon Health Sciences University, absolutely spectacular paper showing that early use of moisturizer in babies seems to prevent or at least delay atopic dermatitis. That's extremely exciting. We've had some ups and downs in this literature, but I think this was an extremely well done study. And I really do think there is something here we need to keep following this thread because if you could just protect against the harsh environment we live in with barrier repair creams, things that are very inexpensive, that would be a game changer. And then of course, we're also now looking at early intervention of existing disease. So babies and kids that have bad eczema. If we treat them more aggressively, is it not possible that we can modify the disease and modify the march so that they don't go on to develop other allergic diseases? I think the answer is a qualified maybe. And it really does seem like there's at least a thread here that if we can figure this out, we could potentially prevent or delay or at least push back against this progression. And that to me is the most exciting thing ever.