A mathematical simulation of the rotational behavior of triaxial ellipsoids in sheared fluid flow is used to evaluate the aerodynamic behavior of fibrous aerosols of circular and non-circular cross-section. A general equation is developed for the average aerodynamic diameter of rotating triaxial fibers, and predicted values are shown to agree with experimentally observed behavior. The aerodynamic properties of non-circular cross-section fibers are seen to differ significantly from those of circular fibers of equal length. The implications of these differences are discussed, with special emphasis on the potential for their exploitation in optimizing the targeted delivery of pharmaceutical agents via therapeutic aerosol treatments.