  We calculate the second order corrections to vacuum polarization tensor of
photons at low temperatures, i.e; T $\le 10^{10}$ K ($T << m_e$). The thermal
contributions to the QED coupling constant are evaluated at temperatures below
the electron mass that is $T< m_e$ . Renormalization of QED at these
temperatures has explicitly been checked. The electromagnetic properties of
such a thermal medium are modified. Parameters like electric permittivity and
magnetic permeability of such a medium are no more constant and become
functions of temperature.
