A criterion for the propagation of weakly-damped spin waves is obtaine
d on the basis of a detailed analysis of the quantum collision integra
l for particles in a paramagnetic polarized Boltzmann gas. it is shown
that according to this criterion spin waves can propagate in classica
l (nonquantum) gases at temperatures close to room temperature. (C) 19
98 American Institute of Physics. [S0021-3640(98)01210-9].