  We study the effect of nonmagnetic impurities on the local density of states
(LDOS) in s-wave superconductors. The quasiclassical equations of
superconductivity are solved selfconsistently to show how LDOS evolves with
impurity concentration. The spatially averaged zero-energy LDOS is a linear
function of magnetic induction in low fields, N(E=0)=cB/H_{c2}, for all
impurity concentration. The constant of proportionality "c" depends weakly on
the electron mean free path. We present numerical data for differential
conductance and spatial profile of zero-energy LDOS which can help in
estimating the mean free path through the LDOS measurement.
