There are several types of inlet coverings (how the respirator attaches to
the user) for air-purifying respirators. For non-powered air-purifying
respirators, these include either a filtering facepiece, a mouth-bit, a
quarter mask, a half mask, or a full facepiece. For powered air-purifying
respirators, these include a half mask, a full facepiece, a hood (loose or
tight fitting) or a helmet (loose fitting).
A respirator inlet covering is the portion of the respirator that forms the
protective barrier between the userís respiratory tract and an air-purifying
device or breathing air source, or both. It may be a facepiece, a helmet, a
hood, a suit, or a mouth-bit with a nose clamp.