Disclosed is apparatus for collecting a breath sample from a human subject, the apparatus comprising at least a mask portion which, in use, is positioned over the subject's mouth and nostrils so as to collect breath exhaled from the subject, the apparatus further comprising movement detection means for detecting movement of the mask portion, and an alarm signal generator, which alarm signal generator generates an alarm signal if the subject's head is outside a predetermined range of acceptable orientations during collection of a breath sample, but only after the subject's head has been outside the predetermined range of acceptable orientations for a defined or measurable period of time.
