With the recent measurement of full sky cosmic microwave background polarization from WMAP , key cosmological degeneracies have been broken , allowing tighter constraints to be placed on cosmological parameters inferred assuming a standard recombination scenario .
Here we consider the effect on cosmological constraints if additional ionizing and resonance radiation sources are present at recombination .
We find that the new CMB data significantly improve the constraints on the additional radiation sources , with \log _ { 10 } [ \epsilon _ { \alpha } ] < -0.5 and \log _ { 10 } [ \epsilon _ { i } ] < -2.4 at 95 \% c.l .
for resonance and ionizing sources respectively .
Including the generalized recombination scenario , however , we find that the constraints on the scalar spectral index n _ { s } are weakened to n _ { s } = 0.98 \pm 0.03 , with the n _ { s } = 1 case now well inside the 95 \% c.l..
The relaxation of constraints on tensor modes , scale invariance , dark energy and neutrino masses are also discussed .