From: Clinical review: Use of helium-oxygen in critically ill patients
Density (ρ; g/l)
Viscosity (μ; micropoises)
Thermal conductivity (K; μcal/s/°K)
Helium
0.1785
188.7
352
Oxygen
1.251
167.4
58
Nitrogen
1.429
192.6
58.5
Air
1.293
170.8