Ratio of expected to observed Q(H⁰) for all the H II regions hosting YSCs or WR stars. The black dashed line indicates a ratio of 1 (f_esc = 0). Top panel: Q ratio as function of the age of the youngest cluster (t_min) hosted in each region, colour coded by the region’s average extinction. Bottom panel: Q ratio as function of the total mass in clusters younger than 10 Myr, colour coded by galactocentric distance.