Methods and devices for creating an artificial exhalation profile, for example for use in the sampling of exhaled breath or air from the nasal cavity from a mammal, wherein said mammal exhales into a device comprising a flow channel, a pressure sensor, a flow sensor, a control unit, and means for creating an exhalation flow, wherein said means for creating an exhalation flow maintain an exhalation flow at one or more pre-determined flow rate (rates), within a predetermined interval, substantially independent of exhalation pressure.
