The effect of a constant magnetic field in combination with a field induced by an external thermal environment on atomic decay rates is studied. For this purpose, radiative corrections including magnetic interaction are considered for hydrogen and hydrogen-like ions with a small nuclear charge Z. Corrections to the decays of the metastable state 2s and the excited state 2p were calculated at various magnetic field strengths suitable for the conditions of the laboratory experiments. It is found that the combination of the magnetic field and thermal environment can lead to a broadening close to the level of experimental error, which makes it necessary to take them into account in the near future.