  Decay of $^{210}$Po compound nucleus formed in light and heavy-ion induced
fusion reactions has been analyzed simultaneously using a consistent
prescription for fission barrier and nuclear level density incorporating shell
correction and its damping with excitation energy. Good description of all the
excitation functions have been achieved with a fission barrier of 21.9 $\pm$
0.2 MeV. For this barrier height, the predicted statistical pre-fission
neutrons in heavy-ion fusion-fission are much smaller than the experimental
values, implying the presence of dynamical neutrons due to dissipation even at
these low excitation energies ($\sim$ 50~MeV) in the mass region A $\sim$ 200.
When only heavy-ion induced fission excitation functions and the pre-fission
neutron multiplicities are included in the fits, the deduced best fit fission
barrier depends on the assumed fission delay time during which dynamical
neutrons can be emitted. A fission delay of (0.8 $\pm$ 0.1 )$\times 10^{-19}$ s
has been estimated corresponding to the above fission barrier height assuming
that the entire excess neutrons over and above the statistical model
predictions are due to the dynamics. The present observation has implication on
the study of fission time scale/ nuclear viscosity using neutron emission as a
probe.
