Introduction:
Long-term exposure to ambient air pollution is a significant public health concern, yet its specific association with skin diseases in the Chinese middle-aged and older population remains insufficiently characterized, with limited evidence on the role of individual pollutants.

Material and methods:
We analyzed prospective data from the China Health and Retirement Longitudinal Study (CHARLS), a nationally representative cohort. Participants aged ≥ 45 years from the 2011 baseline survey were followed through 2018. Annual average concentrations of PM_2.5, PM₁₀, NO₂, SO₂, and PM1 at participants’ community residences were assessed using satellite-based models with 1-km resolution. Skin disease was defined by a self-reported physician diagnosis or related symptoms. Multivariable logistic regression models were used to estimate odds ratios (ORs), adjusting for demographic, socioeconomic, lifestyle, and health-related covariates. Sensitivity analyses included age-restricted (≥65 years) and incident-case cohorts, and propensity score matching.

Results:
Among 7,894 participants, long-term exposure to higher levels of PM_2.5 (fully adjusted OR = 1.25, 95% CI: 1.13–1.38), PM₁₀ (OR = 1.18, 95% CI: 1.04–1.32), and NO₂ (OR = 1.15, 95% CI: 1.02–1.29) was significantly associated with higher odds of skin disease. Associations for SO₂ and PM1 were not statistically significant. Results remained consistent across all sensitivity analyses, supporting the robustness of the findings.

Conclusions:
This national cohort study provides evidence that long-term exposure to PM_2.5, PM₁₀, and NO₂ is associated with higher odds of skin diseases among Chinese middle-aged and older adults. These findings suggest that air pollution control may represent a potential intervention target for reducing the burden of skin disease in aging populations.