A breathing apparatus, including: a mask adapted to substantially surround at least the mouth or nostrils of a user; and a neck component attached to said mask, adapted to substantially surround the back of the neck of said user, said neck component including a flow generator to receive unfiltered air from a surrounding environment, filter said unfiltered air, and, provide filtered air to said mask; an inlet air channel arranged to convey air from the flow generator to the mask; and an outlet air channel, separate from the inlet channel, arranged to convey air from the mask, wherein the inlet air channel and outlet air channel open to the mask at opposite sides of the mask, so that the air flow is arranged to flow across the mouth or nostrils of the user from one side of the user's head to the other side of the user's head; characterised in that the breathing apparatus further includes an engagement arrangement for engaging the neck component to the mask, comprising a mask portion including a first cooperating air channel apparatus, a neck portion including a second cooperating air channel apparatus, and cooperating mating clips (25, 26); wherein the cooperating mating clips (25, 26) releasably engage the mask portion to the neck portion, forming a seal therebetween; and the cooperating mating clip on the side of the neck portion includes a means for adjusting the size of the breathing apparatus, comprising a rigid link extending between the neck portion and the neck component, and a ratchet mechanism to adjust the length of the rigid link, such that the rigid link may be readily shortened, but is prevented from being lengthened until a release button is pressed. a mask adapted to substantially surround at least the mouth or nostrils of a user; and a neck component attached to said mask, adapted to substantially surround the back of the neck of said user, said neck component including a flow generator to receive unfiltered air from a surrounding environment, filter said unfiltered air, and, provide filtered air to said mask; an inlet air channel arranged to convey air from the flow generator to the mask; and an outlet air channel, separate from the inlet channel, arranged to convey air from the mask, wherein the inlet air channel and outlet air channel open to the mask at opposite sides of the mask, so that the air flow is arranged to flow across the mouth or nostrils of the user from one side of the user's head to the other side of the user's head; characterised in that the breathing apparatus further includes an engagement arrangement for engaging the neck component to the mask, comprising a mask portion including a first cooperating air channel apparatus, a neck portion including a second cooperating air channel apparatus, and cooperating mating clips (25, 26); wherein the cooperating mating clips (25, 26) releasably engage the mask portion to the neck portion, forming a seal therebetween; and the cooperating mating clip on the side of the neck portion includes a means for adjusting the size of the breathing apparatus, comprising a rigid link extending between the neck portion and the neck component, and a ratchet mechanism to adjust the length of the rigid link, such that the rigid link may be readily shortened, but is prevented from being lengthened until a release button is pressed.