1 INTRODUCTION
2 SURVEYS
2.1 NH₃ catalogues
2.2 Hi-GAL catalogue of physical properties of Galactic clumps
2.3 Cross matching and sample selection
2.4 Beam filling factors
3 RESULTS
3.1 Distance-independent parameters derived from gas and dust emission
3.2 Distances
3.3 Distance-dependent parameters
3.4 Criteria for high-mass star formation
3.5 Comparison with the general population of Hi-GAL sources
4 DISCUSSION
4.1 Correlation between evolutionary indicators
4.2 Coupling between gas and dust temperatures
4.3 Virial parameters
4.4 Non-thermal motions driven by gravitational collapse
4.5 Distribution of NH₃ fractional abundances as a function of Galactocentric distances
4.6 Comparison with NH₃ properties of low and high-mass star forming cores
5 CONCLUSIONS