Notes. ^(*) The indicated uncertainties are mainly due to age uncertainties of the sources and the boundary conditions of the chosen integration limits (inner and outer shell radii). Early sources such as NGC 1333-IRAS 2A-1 and L1544 show a high age dependence for HOOH. ^(**) Column densities were obtained by applying the rotational diagram technique. For HOOH, the observational upper limit is determined using the average and broader line width values from Table 3. ^(a) A temperature of 21.4 K (model value) was assumed. However, the value of the column density is not very temperature sensitive, i.e., assuming T = 25 K results in nearly the same N_T. ^(b) Assuming an expected line width of1.5 km s⁻¹. The 219 GHz rms level was used. Fitted assuming T = 21.5 K (model value). ^(c) Assuming a temperature at 21.4 K (model value). The 143 GHz rms was used (because of the longest integration time). ^(d) Temperature taken from Tafalla et al. (1998). ^(e)Assuming a temperature at 12.5 K (Tafalla et al. 1998) and using the 143 GHz rms level.