Risk for atopic dermatitis associated with proximity to major roadways

SAN ANTONIO — Living further from major roadways correlated with reduced risk for atopic dermatitis, according to a study presented at the American Academy of Allergy, Asthma & Immunology Annual Meeting.

“We are becoming increasingly aware of the importance of air quality in the pathogenesis of a variety of conditions, including allergic conditions,” Michael Nevid, MD, fellow in pediatric allergy and immunology at National Jewish Health, told Healio. “There have been many studies evaluating the effects of traffic related air pollution on asthma, but relatively fewer in regards to atopic dermatitis. There have been a few recent studies in Asia showing this effect. We wanted to see if we see a similar trend here in the U.S.”

Nevid and colleagues performed a 13-year retrospective chart review of children and adolescents aged 0 to 18 years, including 7,384 patients diagnosed with atopic dermatitis and an age- and sex-matched control group of 7,241 individuals without the condition.

Researchers then used the patients’ residential addresses to geocode their coordinates and distance from a major roadway, defined as those having an average annual daily traffic of more than 10,000 vehicles.

Using linear regression, researchers found an 18.8% decrease in odds for atopic dermatitis with every factor 10 increase in distance from a major road (P = .000015).

Conversely, children who lived 1,000 m or more from the nearest major road had 26.1% (95% CI, 13.4%-36.9%) lower odds of AD compared with patients who lived 500 meters or closer from the nearest major road.

“I was surprised by the magnitude of the results,” Nevid said. “I expected we would see a more subtle increase in risk of AD in regards to residential distance from highways, but not a 27% lower odds in those living greater than 1 km from a major road as compared to those living within 500 m.”

Nevid and colleagues also performed an analysis adjusting for race and ethnicity, “which continued to show the finding that those living greater than 1 km from a major road or highway are less likely to have atopic dermatitis than those living within 500 m,” he said. “Thus, we believe these findings to be important for urban residents including non-Hispanic Black [residents].”

According to Nevid, the study helps to support the idea that where an individual lives may have health impacts relating to air pollution exposure, making measures to help reduce air pollution in children important to consider.

“It is also important for providers to be aware of this association so that they can appropriately screen their patients who may be at higher risk of atopic dermatitis depending on where they live. The specific type of inflammation induced by air pollution may be the target of therapeutic interventions in the future,” he said.

However, Nevid pointed out that, despite the findings demonstrating an inverse association, they do not imply causation either.

“Thus, our next steps include developing mechanistic studies that may show that traffic-related air pollution causes skin barrier dysfunction leading to atopic dermatitis. Such studies are necessary to determine a causative link between air pollution and atopic dermatitis,” he said.

Reference:

• Living near a major road may be associated with a higher risk of atopic dermatitis. https://www.aaaai.org/About/News/News/2023/road. Published Feb. 3, 2023. Accessed Feb. 21, 2023.