Conversion factors α between integrated opacity to column density derived with RADEX for the fundamental transitions of NH₂D and HDO, for a range of standard conditions in the interstellar medium. We assume the OPR = 3. For the o-NH₂D (1_1, 0–0_0, 0) transition, the conversion factor corresponds to the calculation with a collapsed hyperfine structure, i.e., 9 times lower than for an equivalent component with line strength of 1 (Tables 2 and A.4). The white curve indicates a departure of 10% over the pure radiative equilibrium calculation for T_ex = T_CMB = 5.14 K. The white dotted box labeled “SW los” indicates the range of densities and temperatures previously estimated in the line of sight to the SW image of PKS 1830−211 by Muller et al. (2013).