  We apply the theory of cotorsion pairs to study closure properties of classes
of modules with finite projective dimension with respect to direct limit
operations and to filtrations.
  We also prove that if the ring is an order in an $\aleph_0$-noetherian ring Q
of small finitistic dimension 0, then the cotorsion pair generated by the
modules of projective dimension at most one is of finite type if and only if Q
has big finitistic dimension 0. This applies, for example, to semiprime Goldie
rings and Cohen Macaulay noetherian commutative rings.
