Aims To assess the association of air pollution exposure at different time scales with arterial stiffness in participants with and without atherosclerotic cardiovascular disease (ASCVD). Methods We measured participants' arterial stiffness with brachial-ankle pulse wave velocity (baPWV) from October 2016 to January 2020. Concentrations of air pollutants including fine particles < 2.5 mu m aerodynamic diameter (PM2.5), inhalable particles < 10 mu m aerodynamic diameter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O-3) measured by fixed ambient air monitoring stations were collected for short- (7-day) and long-term (365-day) exposure assessment. We used generalized estimating equations (GEEs) to analyze and further explored the modification effects between ASCVD and air pollutants. Results Seven hundred sixty-five participants were finally included and four hunderd sixty (60.1%) participants had a history of ASCVD. Based on the partial regression coefficients (beta) and 95% confidence intervals (95% CI) calculated from GEEs using linear regression, each 10 mu g/m(3) increase in long-term exposure to PM2.5 and PM10 was associated with 31.85 cm/s (95% CI, 17.97 to 45.73) and 35.93 cm/s (95% CI, 21.01 to 50.84) increase in baPWV. There was no association between short-term exposure to air pollution and arterial stiffness. Although no significant interaction effect was observed between air pollution and ASCVD, baPWV showed a greater increment in the subgroup without ASCVD. Conclusion Long-term exposure to air pollution is closely associated with higher arterial stiffness in participants with and without ASCVD. Reducing air pollution exposure is essential in the primary and secondary prevention of ASCVD.