Spectral evolution, relative to the local interstellar spectrum q_LIS, of the γ-ray emissivities of the local gas components. q_CO is given in units of 10²⁰ cm^-2 (K km s^-1)^-1 and q_DNM in 10²⁵ cm^-2. The q_HI normalizations are given for a spin temperature of 400 K. The dashed lines compare the results obtained for the whole 0.4–100 GeV band to the results of the four independent bands. All error bars are symmetrical; horizontal error bars at the boundaries are truncated.