Polarization and anisotropy of the relict radiation in an anisotropic universe

A rigorous first order solution with respect to anisotropy is obtained for the equation of polarized radiation transfer in a homogeneous anisotropic universe with a flat co-moving space. The degree of polarization of the background radiation is shown to be very sensitive to the recombination dynamics and to the secondary reheating epoch. Provided that a quadrupole anisotropy of the background radiation is established, the measurements of its polarization degree enable one to set severe limitations on the conditions of secondary ionization.