The following describes gas masks, including all fully assembled air purifying masks, that can be used to protect the lungs from harmful atmospheres.

(1) Gas mask that can be mounted front or backward.

A gas mask that includes a complete facepiece, breathing tube, canister at the back or front, canister harness, and all associated connections. You can buy gas masks via https://www.gasmaskpro.com/.

(2) Chin-style gasmask.

A gas mask that includes a complete facepiece, a canister, and any associated connections.

(3) Escape gas mask.

A gas mask that is used to escape from dangerous atmospheres. It consists of a mouthpiece or facepiece, a canister, and any other connections.

Gas masks are further described according to the type of gases or vapors against which they are intended to provide respiratory protection.

Approval can be given for acid gases and organic vapors in general or for specific acids gases or organic vapors.

Not to be used against gases or vapors that have poor warning properties (except where MSHA and Occupational Safety and Health Administration standards allow such use) or those that generate high heats or react with sorbent material in the canister.

The use of the gas mask could be restricted by factors like lower explosive limit, toxicological consequences, and fit of the facepiece. The applicant must specify in the instructions for selecting, using, and maintaining the gas mask any limitations on the gas mask's service life or sorbent capacities.