A centrifugal air impeller, including: a hub rotatable on a hub axis and having a hub outer periphery disposed circumferentially about the hub axis, a plurality of blades spaced apart from the hub; and a blade mounting structure, narrower axially than the blades, supporting the blades integrally relative to the hub and spaced apart from the hub in a circumferential sequence about the hub for rotation with the hub about the hub axis in a forward direction to determine in each blade a leading edge and a trailing edge, the blade mounting structure further supporting the blades inclined relative to the hub to select one of the leading and trailing edges (42, 44) as a proximate edge spaced radially from the hub outer periphery by a first distance and to select the other of said leading and trailing edges (42, 44) as a remote edge spaced radially from the hub outer periphery by a second distance greater than the first distance; wherein the blade mounting structure comprises a plurality of first structural segments coupled with respect to the hub and associated individually with the blades, with each first structural segment coupled to its associated blade at a first location near the proximate edge, the blade mounting structure further comprising a plurality of second structural segments associated individually with adjacent pairs of the blades, each second structural segment coupled to a first blade of its associated pair at a second location between the first location and the remote edge and coupled to a second blade of the associated pair to couple the first and second blades, the centrifugal air impeller being characterised in that the first and second structural segments comprise struts, each strut having a circumferential width and an axial thickness that is less than the circumferential width and varies gradually between a maximum thickness along a medial portion of the strut and reduced thicknesses at forward and rearward edge portions of the strut. a hub rotatable on a hub axis and having a hub outer periphery disposed circumferentially about the hub axis, a plurality of blades spaced apart from the hub; and a blade mounting structure, narrower axially than the blades, supporting the blades integrally relative to the hub and spaced apart from the hub in a circumferential sequence about the hub for rotation with the hub about the hub axis in a forward direction to determine in each blade a leading edge and a trailing edge, the blade mounting structure further supporting the blades inclined relative to the hub to select one of the leading and trailing edges (42, 44) as a proximate edge spaced radially from the hub outer periphery by a first distance and to select the other of said leading and trailing edges (42, 44) as a remote edge spaced radially from the hub outer periphery by a second distance greater than the first distance; wherein the blade mounting structure comprises a plurality of first structural segments coupled with respect to the hub and associated individually with the blades, with each first structural segment coupled to its associated blade at a first location near the proximate edge, the blade mounting structure further comprising a plurality of second structural segments associated individually with adjacent pairs of the blades, each second structural segment coupled to a first blade of its associated pair at a second location between the first location and the remote edge and coupled to a second blade of the associated pair to couple the first and second blades, the centrifugal air impeller being characterised in that the first and second structural segments comprise struts, each strut having a circumferential width and an axial thickness that is less than the circumferential width and varies gradually between a maximum thickness along a medial portion of the strut and reduced thicknesses at forward and rearward edge portions of the strut.