Background/aim Atherosclerosis and arterial stiffness have been linked to air pollution. However, the association between long-term exposure to air pollution and abnormal ankle-brachial index (ABI) has not been fully investigated. We aimed to examine the long-term effects of air pollution on the prevalence of low and high ABI, and the potential effect modification by individual characteristics.

Methods This cross-sectional study involved 4544 participants from the KORA F3 (2004–2005) and F4 (2006–2008) surveys in the region of Augsburg, Germany. Participants’ residential annual mean concentrations of particulate matter and nitrogen dioxide were predicted with land-use regression models, and information on traffic indicators was collected from geographic information systems. We assessed the effects of air pollution on the prevalence of low and high ABI by multinomial logistic regression models adjusted for demographic, socioeconomic, and lifestyle confounders. We also applied quantile regression models to explore the non-monotonic relationship between air pollution and ABI. Potential modification effects were examined for age, sex, physical activity, overweight, and comorbidities.

Results Long-term exposure to particulate matter with aerodynamic diameter ≤10 µm (PM10) and ≤2.5 µm (PM2.5) was significantly associated with the prevalence of low ABI, with the respective odds ratios (ORs) of 1.78 (95% CI: 1.09 to 2.92) and 1.63 (95% CI: 1.03 to 2.58) for an increment from the 5th to the 95th percentile in concentration. For high ABI, the association was significant for PM2.5 absorbance (OR=1.54, 95% CI: 1.07 to 2.24) and traffic load within 100 m of the residence (OR=1.39, 95% CI: 1.04 to 1.86). Quantile regression analyses revealed similar results. The effect of air pollution on having low ABI was stronger in participants who did little or no physical exercise.

Conclusion Long-term exposure to air pollution was associated with an increased risk of having abnormal ABI, and the association was modified by physical activity. This study provides evidence for the air pollution effects on atherosclerosis and arterial stiffness in lower extremities.