Air pollution is responsible for millions of global deaths annually. The most dangerous gaseous pollutants are sulfur dioxide (SO_{2}), carbon monoxide (CO), and nitrogen oxides (NO_{x}), which have been linked to an increased risk of cardiac arrhythmias. However, the underlying mechanisms have not been fully established in humans. This study uses multiscale atrial models to assess the effects of individual gaseous pollutants at low, medium, and high concentrations. For this, mathematical equations describing the effects of these pollutants were included in an atrial cell model to evaluate the electrophysiological characteristics. Then, the modified cell model was incorporated into a 3D model of human atria to evaluate the propagation dynamics. The results indicate pro-arrhythmic effects in a concentration-dependent manner. SO_{2} was the pollutant with the highest effects, achieving an action potential duration decrease and triggering the most chaotic and disordered propagation characterized by several re-entries. In conclusion, gaseous air pollutants, particularly SO_{2} and CO at high concentrations, show pro-arrhythmic effects in a concentration-dependent manner. © 2023 CinC.