  We prove an analogue of the result of Hsiang and Kleiner for 4-dimensional
compact orbifolds with positive curvature and an isometric circle action.
Additionally, we prove that when the underlying space is simply connected, then
the orbifold fundamental group provides a bound on the failure of
integer-valued Poincare Duality of the underlying space, and if the orbifold is
simply connected, then ineteger-valued Poincre Duality holds for the underlying
space.
