We study the blow-up set of a solution u(x,t) to the porous medium equation, ut = δ(um), in ω x (0,T) for two different boundary conditions, u(x,t)=f (x)/(T - t)1/m-xor -∂um/∂n̂(x,t) = g(x)/(T - t)m/m-1 on ∂ω× (0,T). Here m > 1 and ω is a bounded smooth domain in ℝN. We establish point-wise and integral conditions on f and g respectively in order to obtain regional or global blow-up.