Higher Air Pollution and Extreme Weather Linked to Adult Atopic Dermatitis

Higher levels of air pollution and extreme weather are linked to increased rates of atopic dermatitis, especially in adults, according to a new global analysis of 42 studies published in JAMA Dermatology.

Climate change and air pollution are growing threats to public health, and new research suggests they may also worsen atopic dermatitis (AD), the most common chronic inflammatory skin condition, affecting up to 15% of people worldwide.

In the U.S., an estimated 16.5 million adults live with AD, including 6.6 million with moderate to severe forms of the disease.

Among children, roughly 9.6 million are affected, with one-third experiencing moderate to severe symptoms.

While previous research has mostly focused on children, the link between environmental exposures and AD in adults remains less understood.

Some studies have found that higher levels of air pollutants—such as particulate matter (PM), carbon monoxide (CO) and nitrogen dioxide (NO₂)—are associated with more severe symptoms and more frequent flare-ups.

Other studies suggest that both hot and cold temperatures can trigger symptoms, although the effects vary by individual and setting.

In addition, people living in urban areas have a significantly higher prevalence of AD than those in rural areas, likely due to greater pollution and reduced access to green space.

Despite these findings, the evidence has been inconsistent, and no comprehensive review has focused specifically on adult cases—until now.

This systematic review and meta-analysis aimed to fill that gap by evaluating how air pollution, climate, and weather conditions are associated with disease outcomes in adults with AD.

Researchers searched MEDLINE, Embase and the Cochrane Central Register for studies published up to June 28, 2024, that examined environmental exposures and AD in adults.

Eligible studies included observational research—such as cohort and cross-sectional studies—that investigated exposures like air pollution (PM2.5, NO₂), temperature, humidity, sunlight, and secondhand smoke.

Five reviewers independently screened articles and extracted data.

Studies were included if more than 50% of participants were adults.

Meta-analyses were performed when at least three studies had comparable data; others were summarized narratively.

Risk of bias and certainty of evidence were assessed using standard tools, including the GRADE approach.

The final analysis included 42 studies from 14 countries.

Even small increases in air pollutants such as PM10, PM2.5, sulfur dioxide (SO₂) and nitrogen dioxide (NO₂) were associated with more emergency room or outpatient visits for AD, especially in heavily polluted cities including Beijing and Chengdu.

While the strength of evidence varied, the direction of the findings was generally consistent: higher pollution levels were linked to increased disease activity.

Temperature extremes were another key factor.

Both hot and cold weather were associated with worsening symptoms, with women appearing more sensitive to high temperatures.

Humidity and seasonal changes also showed mixed effects. Some studies reported flare-ups during dry seasons, while others noted increased severity during rainy periods.

Exposure to secondhand smoke and proximity to traffic or industrial areas also raised the risk of developing or worsening AD.

In comparison, results were inconsistent for carbon monoxide and sunlight exposure.

Overall, the review’s broad scope is one of its major strengths, as it’s among the first to look at environmental impacts on adult AD across diverse global populations.

The findings align with existing mechanistic evidence, including research showing how air pollutants can trigger immune responses that inflame the skin.

However, limitations do exist.

There was considerable variation in how pollutants were measured across studies, and socioeconomic and age-specific data were often missing.

Many studies also focused on moderate-to-severe cases, limiting generalizability to those with milder forms of the disease.

The authors recommend further research to better understand how environmental exposures affect different populations over time, especially in low-income regions where pollution levels are higher and data are scarce.

They also call for public health strategies to reduce exposure and promote health equity—particularly for vulnerable groups like older adults and women.