The σ_vel versus σ diagram. The solid line indicates the linear regression (the dashed line highlight the extremes of the distribution) througth the distribution of simulated H ii regions for different inclination angles from Lagrois et al. (2011) and Arthur & Hoare (2006). The vertical dash-dotted line indicates the separation between H ii regions in champagne phase perturbed (on the right) or not (on the left) by an expanding wind bubble. The squares show the optical H ii regions listed in Table 1. The arrows indicate the possible shift resulting from the extinction effect.