The full-face gas mask includes a filter cartridge, flexible cover piece, clear eye lenses, and several straps and bands that hold it in place. A filter cartridge is a 3-4 inch (8-10 cm) wide and 1 in (2.5 cm deep) thick plastic container that contains a filtration agent. Because they can absorb large amounts of organic gases, particularly high molecular weight vapors such as those used in chemical warfare, carbon-based filtrates are common.
Inorganic vapors, however, are not as strong as carbon. You can enhance the adsorptive qualities of carbon by impregnating it with specific reactants and decomposition catalysts. This chemically treated carbon is called "activated carbon". Today, almost every gas mask manufacturer design gas masks with an activated charcoal filter system. You can check out these modern gas masks on https://www.gasmaskpro.com/with activated charcoal filter systems.
The specific industrial contaminant being screened will determine the type of activated carbon used in a particular filter cartridge. To screen out formaldehyde, hydrogen cyanide, and cyanogen chloride, activated carbon with a mixture of copper and chromium has been used since the 1940s.
A combination of molybdenum, triethylenediamine, and chromium toxicity is now used. To trap contaminants, other types of activated carbon use silver or zinc oxides. To absorb sewage vapors (hydrogen sulfide), chlorine, and other harmful gases, sodium-, potassium-, and alkali-treated carbon are used.