<p>This study examines the effect of wind catchers (WC) on airflow and pollutant dispersion in a street canyon using a validated numerical model based on wind tunnel data. Both low-rise (H/W = 1) and high-rise (H/W = 2) canyons with a length-to-height ratio of 10 and wind catchers covering the entire roof of the upwind building are simulated, taking into account various structural parameters of the wind catchers. The findings emphasize the key role of wind catcher inlet height in influencing induced flow and suggest that wind catchers are more effective in high-rise than low-rise canyons. In both settings, taller inlet heights significantly enhance the net escape velocity (NEV*). The WCs with a low inlet height (a = H /12) are ineffective for diluting traffic pollutants at the pedestrian respiration planes and on the canyon walls. Additionally, introducing a wind catcher with a high inlet height (a = H/6) and increasing the outlet width (c) significantly enhances the NEV*, while the vertical length of the WC (b) has only a negligible impact on the NEV*. Moreover, when a WC with a high inlet height is utilized, pollutant concentrations at the canyon walls and pedestrian respiration planes are minimally affected by variations in the vertical length and outlet width of the wind catcher. Optimal structural parameters are identified for both low-rise and high-rise canyons to minimize pollutant exposure risks.</p> Graphical abstract <p>This study examines the influence of the structural parameters of wind catchers on airflow and pollutant dispersion within street canyons. It identifies effective design parameters that can significantly reduce pollutant concentrations in both low-rise and high-rise canyons.</p>