: a pocket-size respirator for emergency use that protects the wearer for a period of about one-half hour against atmospheres containing carbon monoxide gas (as in a contaminated mine)

What does a self rescuer do?

An oxygen self rescuer or self-contained rescue device (SCSR) is a portable piece of equipment that supplies breathable air when the surrounding atmosphere lacks oxygen or is contaminated with toxic gases, such as carbon monoxide.

What is the chemical in a self rescuer?

Oxygen Self rescuers provide Oxygen on demand for a set period of time by generating Oxygen from a chemical known as KO2. Self Rescuer Units have a closed breathing circuit and the exhaled air of the wearer is regenerated and enriched with Oxygen.