Univariable and multivariable regression results.

<div><p>Background</p><p>The prevalence of eczema has increased with industrialization. Industrial practices generate ambient air pollution, including fine particulate matter of diameter ≤ 2.5μm (PM<sub><b>2.5</b></sub>). Studies investigating the relationship between PM<sub><b>2.5</b></sub> and eczema in the US are scarce. The objective of this study was to determine the risk of eczema with PM<sub><b>2.5</b></sub> exposure in a diverse national cohort of American adults.</p><p>Methods</p><p>In this cross-sectional study, eczema cases in the <i>All of Us</i> Research Program were linked via three-digit zip code to average annual PM<sub>2.5</sub> concentrations from the Center for Air, Climate, and Energy Solutions. Eczema cases and controls were compared using Pearson’s χ<sup>2</sup> test for categorical variables and one-way analysis of variance for continuous variables. The relationship between PM<sub>2.5</sub> and eczema was assessed via logistic regression adjusting for demographic factors, smoking, and atopic comorbidities.</p><p>Results</p><p>Individuals with eczema (n = 12,695) lived in areas with significantly higher PM<sub>2.5</sub> concentrations than did individuals without eczema (n = 274,127) (0.83 x 10 μg/m<sup>3</sup> v. 0.81 x 10 μg/m<sup>3</sup>, <i>P</i> < .001). PM<sub>2.5</sub> concentration was significantly associated with eczema in univariable analysis (odds ratio 1.97, 95% confidence interval 1.77–2.19, <i>P</i> < .001), and in multivariable analyses, both controlling for demographics and smoking status (odds ratio 2.21, 95% confidence interval 1.98–2.47, <i>P</i> < .001) and with the addition of atopic comorbidities (odds ratio 2.38, 95% confidence interval 2.12–2.67, <i>P</i> < .001).</p><p>Conclusions</p><p>The odds of eczema increased with greater PM<sub>2.5</sub> concentration in this large, diverse, adult American cohort. Ambient air pollution is an environmental hazard that influences inflammatory skin disease, suggesting possible targeted interventions.</p></div>