Abstract: A spirometer having a housing with an elongated flow chamber open at one end, a pressure sensing end opposite the open end and an outlet passageway intercepting the flow chamber at an angle ? and proximate the pressure sensing end. A differential pressure sensor is coupled to the pressure sensing end from a port at an angle ? to an axis of the flow chamber. The angle ? is substantially greater than 0° but substantially less than 180° while the angle ? may range from 90° to 180°, such that a significantly increased measured air pressure results over that measured when ?=180° and ?=90°.