Lower limits on the dust masses derived from the observed α_200−300 and F_{250 GHz} (for details, see Section 5). Blue and red symbols show the estimates obtained by adopting ﹩({T}_{{\rm{dust}}},{a}_{{\rm{\max }}})﹩ = (24 K, 3 mm) and (100 K, 0.05 mm), respectively. Open circles indicate sources for which the model spectral index does not become lower than the observed α_200−300 within the explored range of Σ_dust; their inferred dust masses therefore correspond to the adopted upper boundary of Σ_dust and should be interpreted as lower limits. Filled circles indicate sources for which a minimum Σ_dust is identified within the explored range.