Evolution of the X_CO factors and of the average dust properties per gas nucleon in the DNM, as measured in γ rays for different linear resolutions in the clouds. The black triangles mark the γ-ray measurements in the overall energy band, in close agreement with the weighted average of the other four independent estimates (thin lines) and their ± 1 σ errors (dashed lines). The X_CO factors obtained from the dust fits are shown as open symbols (circle for A_VQ, diamond for τ₃₅₃, and cross for R).