CONCERTO probed the long-wavelength emissivity of dust in external galaxies and how it changes across different galactic environments (disc, spiral arm, nucleus). Combining CONCERTO, NIKA2, and Herschel data provided additional input into comprehensive SED models (e.g. Galliano et al. 2011) and enabled investigation of changes in the emissivity index. Of particular interest was the possibility of excess long-wavelength emission over and above that predicted by Herschel data. This excess is not clearly understood. It may indicate a significant cold dust component (T<15K) and/or physically different dust.

Understanding how dust properties evolve as a function of metal enrichment provided important constraints for galaxy evolution studies. Dwarf galaxies in the local Universe were ideal targets for such a study as many of them have low metallicity and high star-formation activity. As such, they present star formation properties and ISM conditions that are the closest analogues to those thought to be present in the primordial environments of the early Universe. Accurate maps of the dust mass surface density obtained using CONCERTO were combined with HI and H2 (CO) maps to give the spatial variation of the gas-to-dust ratio. The gas-to-dust ratio is a crucial input into chemical evolution models that predict the metallicity as a function of the gas fraction. When combined with the gas phase metallicity, the fraction of metals in both gas and dust could be measured. Using samples ranging from metal-poor to metal-rich environments, CONCERTO allowed derivation of the gas-to-dust mass ratios as a function of metallicities.