We have performed a likelihood analysis of the recent data on the Cosmic Microwave Background Radiation ( CMBR ) anisotropy taken by the Boomerang experiment .
We find that this data places a strong upper bound on the radiation density present at recombination .
Expressed in terms of the equivalent number of neutrino species the 2 \sigma bound is N _ { \nu } \leq 13 , and the standard model prediction , N _ { \nu } = 3.04 , is completely consistent the the data .
This bound is complementary to the one found from Big Bang nucleosynthesis considerations in that it applies to any type of radiation , i.e .
it is not flavour sensitive .
It also applies to the universe at a much later epoch , and as such places severe limits on scenarios with decaying neutrinos .
The bound also yields a firm upper limit on the lepton asymmetry in the universe .