A gas mask is also called air-purifying respirator. It consists of a mask with a chemical cartridge or canister for air purification. It is intended for air purification purposes and does not have an independent supply of oxygen. The gas mask is secured with straps around the head and a sealed fit is important to proper functioning.

Gas masks can be used for a wide variety of applications, but the selection of the appropriate filter is essential. There are no universal cartridges that protect the wearer from all airborne pollutants. Thus, different types of cartridges are used for spray-painting, pesticide application, etc. Today gas masks are designed with advanced features and filter systems. You can check out modern protective gas masks via https://www.gasmaskpro.com/. 

Cartridges must be changed on a regular basis. The expiration date of the cartridge acts as a guideline, but cartridges may be required to be changed more frequently depending on exposure to pollutants and frequency of use. There are half-face and full-face respirators. 

Full face respirators protect the wearer from inhaling hazardous vapors, gases, and fumes. Full face respirators protect the face as well as the eyes and filter out contaminants with the help of cartridges or filters, which should be changed regularly in order to ensure effective protection of the wearer.