In an aspect there is disclosed, a fan arrangement for a duct, the fan arrangement including a housing having an inlet and an outlet adapted to communicate air with the duct and an axially rotatably driven impeller supported within the housing between the inlet and the outlet. The impeller includes a hub carrying a plurality of blades that span in a radial direction outwardly of the hub, the plurality of blades being shaped to urge air between the inlet and the outlet. The plurality of blades may have a tip solidity ratio in the range of about 0.8 to 1.2, and each of the plurality of blades may have a twist angle between a root and a tip thereof in the range of about 15 to 30 degrees and a substantially constant thickness. An impellor, a blade, ventilation system and related methods are also disclosed.