A blower includes an electric motor having a shaft, a housing having a housing inlet and a housing outlet between which is defined a flow path for gas, a first impeller having a plurality of blades adapted to accelerate gas tangentially and to direct it radially outward, and a stationary portion. The stationary portion includes a gas flow path defined between an external wall of the motor and a wall of the stationary portion, a first stationary vane structure located downstream of the first impeller, and a shield constructed and arranged 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. The flow path is of sufficient width to allow a flow of gas therethrough without introducing excessive pressure drop.