Respirators

Respirators are worn over the mouth (oral) or mouth and nose (ori-nasal) for changing the properties of the air inspired. The name was first given by Mr Jeffreys to an apparatus he contrived about 1835 for the purpose of warming the air, formed of numerous layers of fine perforated metal with wire soldered to them. Their value in diminishing the risk of catching cold, which in many cases is undoubted, probably depends at least in part on their affording protection to a sensitive portion of the skin; they act, in fact, as an additional article of clothing. But they are of most value to those who are not able to breathe through the nose in the natural way. Respirators have been largely used of late years in diseases of the nose, throat, lungs, &c. for impregnating the inspired air with medicated vapours; for this purpose they are constructed with a chamber containing a sponge or cotton-wool which is kept charged with the substance whose action is desired (carbolic acid, creasote, eucalyptus, or pine-oil, &c.). Respirators have been also devised for freeing the inspired air of impurities—e.g. in the case of firemen, who have to go into an atmosphere strongly charged with smoke; of needle-grinders and others whose work gives rise to much irritating dust; of those who are exposed to foul gases, &c. See FILTER.