A device designed to protect the wearer from inhaling harmful dusts, fumes, vapors, and/or gases. Respirators come in a wide range of types and sizes. There are two main categories: (1) the air purifying respirator, which forces contaminated air through a filtering element, and (2) the air-supplied respirator, in which an alternate supply of fresh air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contaminants.

Some respirators require medical screening and fit testing.

Air Purifying Respirator (APR): Respirators which consist of a facemask and an air-purifying device, which is either attached directly to the mask or carried on a body harness and connected to the mask via a breathing hose. APRs selectively remove specific airborne contaminants (particulate, vapors, fumes, and gases) from ambient air by filtration, adsorption or chemical reactions. Filtering cartridges are removed and replaced at the end of their useful service life. APRs can be either of the full face or half mask varieties.

Powered Air Purifying Respirator (PAPR): A type of air purifyingrespirator whichconsist of a powered fan which forces incoming air through one or more filters for delivery to the user for breathing. The fan and filters may be carried by the user or with some units the air is fed to the user via tubing while the fan and filters are remotely mounted.

Supplied Air Respirator (SAR): Often referred to as an airline respirator. These devices provide air to the user, through an airline, from a source located some distance away.