Association between fine particulate matter and eczema: A cross-sectional study of the All of Us Research Program and the Center for Air, Climate, and Energy Solutions

Background: The prevalence of eczema has increased with industrialization. Industrial practices generate ambient air pollution, including fine particulate matter of diameter ≤ 2.5μm (PM2.5). Studies investigating the relationship between PM2.5 and eczema in the US are scarce. The objective of this study was to determine the risk of eczema with PM2.5 exposure in a diverse national cohort of American adults.

Methods: In this cross-sectional study, eczema cases in the All of Us Research Program were linked via three-digit zip code to average annual PM2.5 concentrations from the Center for Air, Climate, and Energy Solutions. Eczema cases and controls were compared using Pearson's χ2 test for categorical variables and one-way analysis of variance for continuous variables. The relationship between PM2.5 and eczema was assessed via logistic regression adjusting for demographic factors, smoking, and atopic comorbidities.

Results: Individuals with eczema (n = 12,695) lived in areas with significantly higher PM2.5 concentrations than did individuals without eczema (n = 274,127) (0.83 x 10 μg/m3 v. 0.81 x 10 μg/m3, P < .001). PM2.5 concentration was significantly associated with eczema in univariable analysis (odds ratio 1.97, 95% confidence interval 1.77-2.19, P < .001), and in multivariable analyses, both controlling for demographics and smoking status (odds ratio 2.21, 95% confidence interval 1.98-2.47, P < .001) and with the addition of atopic comorbidities (odds ratio 2.38, 95% confidence interval 2.12-2.67, P < .001).

Conclusions: The odds of eczema increased with greater PM2.5 concentration in this large, diverse, adult American cohort. Ambient air pollution is an environmental hazard that influences inflammatory skin disease, suggesting possible targeted interventions.