We consider the partial regularity of
suitable weak solutions of the Navier-Stokes equations in a domain
$D$. We prove that the parabolic Hausdorff dimension of space-time
singularities in $D$ is less than or equal to 1 provided the force
$f$ satisfies $f\in L^{2}(D)$. Our argument simplifies the proof
of a classical result of Caffarelli, Kohn, and Nirenberg, who
proved the partial regularity under the assumption $f\in
L^{5/2+\delta}$ where $\delta>0$.