Environmental Factors Play a Major Role in Atopic Dermatitis

At Dermatology Week 2025, Peter Lio, MD, delved into how environmental exposures are driving the development and worsening of atopic dermatitis (AD) and related conditions such as asthma and allergic rhinitis. His session, “Environmental Impact on Atopy,” explored the mounting evidence that modern environmental and lifestyle changes are compromising the skin barrier and fueling immune dysregulation.

"Atopic dermatitis is a vicious cycle of skin barrier dysfunction, immune activation, microbiome disruption, and behavioral scratching," said Dr Lio. He highlighted that damage to the skin barrier—whether genetic or environmental—allows irritants, allergens, and pathogens like Staphylococcus aureus to enter and release toxins, exacerbating inflammation and itch. While a deficiency in the gene encoding filaggrin explains some cases of eczema, it only accounts for around 15% of cases globally, prompting greater attention to external triggers.

Dr Lio emphasized that environmental pollutants, such as air pollution, diesel exhaust, wildfire smoke, and volatile organic compounds from modern furnishings, are increasingly linked to skin barrier damage. He specifically noted the role of diisocyanates, found in wildfire smoke and vehicle exhaust, in worsening atopic conditions. These pollutants are difficult to avoid, making skin health a broader public health concern.

Beyond pollution, elements of modern life like psychological stress, circadian rhythm disruption from screen use, noise pollution, and even food additives are all contributing to this problem. “We’re not living the way we used to,” Dr Lio said. “And our epithelial barriers—skin, gut, respiratory—are bearing the brunt.”

Importantly, Dr Lio discussed the concept of transcutaneous sensitization, where damaged skin allows allergens such as peanut proteins to enter and trigger systemic allergies. “We used to tell parents to avoid feeding allergenic foods early, but now we know that avoiding skin exposure and strengthening the barrier is key,” he said.

Moisturizers remain a central strategy in restoring skin barrier function. Dr Lio noted studies showing reduced disease severity with consistent use of effective moisturizers and emphasized helping patients find products they will actually use. He acknowledged the complexity of choosing among formulations, citing ingredients like ceramides, niacinamide, and probiotics as potentially beneficial.

“We may not be able to eliminate all environmental triggers,” he concluded, “but we can educate patients and equip them to strengthen their barrier defenses.” As environmental stressors continue to evolve, understanding their dermatologic impact is becoming increasingly urgent.

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Reference
Lio P. Environmental impact on atopy. Presented at: Dermatology Week; May 14–16, 2025; Virtual.