A blower comprising: an electric motor having a shaft , said shaft defines a shaft axis; a housing having a housing inlet and a housing outlet between which is defined a flow path for gas; the housing outlet is structured to direct gas exiting the blower in a substantially axial first direction; the motor has a first side proximal said housing inlet , and a second side distal said housing inlet ; a first impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward and being attached to the shaft on the first side of the motor; a portion of the flow path defined by a gap between the motor external wall and an interior wall of the housing, said flow path allowing a flow of gas to pass around the sides of the motor, said flow path directing gas to flow in a generally axial direction from the first side of the motor to the second side of the motor; a stationary portion including a first stationary vane structure located downstream of the first impeller , the first stationary vane structure adapted to direct gas exiting the first impeller from flowing in a substantially tangential direction to flowing in both a radial and axial direction; a second impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward and being attached to the shaft on the second side of the motor; characterised in that a shield is positioned between the first stationary vane structure and the first impeller that extends radially beyond the outer edge of the first stationary vane structure to provide a barrier between the first stationary vane structure and the blades of the first impeller to isolate leading edges of the first stationary vane structure from an impeller blade pressure pulse by preventing a line-of-sight path between the first stationary vane structure and the plurality of blades of the first impeller. an electric motor having a shaft , said shaft defines a shaft axis; a housing having a housing inlet and a housing outlet between which is defined a flow path for gas; the housing outlet is structured to direct gas exiting the blower in a substantially axial first direction; the motor has a first side proximal said housing inlet , and a second side distal said housing inlet ; a first impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward and being attached to the shaft on the first side of the motor; a portion of the flow path defined by a gap between the motor external wall and an interior wall of the housing, said flow path allowing a flow of gas to pass around the sides of the motor, said flow path directing gas to flow in a generally axial direction from the first side of the motor to the second side of the motor; a stationary portion including a first stationary vane structure located downstream of the first impeller , the first stationary vane structure adapted to direct gas exiting the first impeller from flowing in a substantially tangential direction to flowing in both a radial and axial direction; a second impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward and being attached to the shaft on the second side of the motor; characterised in that a shield is positioned between the first stationary vane structure and the first impeller that extends radially beyond the outer edge of the first stationary vane structure to provide a barrier between the first stationary vane structure and the blades of the first impeller to isolate leading edges of the first stationary vane structure from an impeller blade pressure pulse by preventing a line-of-sight path between the first stationary vane structure and the plurality of blades of the first impeller. <EOS>